Luminous Landscape Forum

Raw & Post Processing, Printing => Colour Management => Topic started by: Hening Bettermann on May 01, 2018, 03:33:18 pm

Title: The sky is blue - or should be...
Post by: Hening Bettermann on May 01, 2018, 03:33:18 pm
Hi!
The sky in this image worries me.

The shot is taken with a camera White Balance of 5000K (according to the menu on the a7r2), my monitor (Eizo CG243W) is calibrated to a target of D50, the ambient light in my room is by D50 Yuji lamps, daylight is excluded. The camera profile is created with DCamProf, the target shot with a Solux lamp run at 15 V to give something near 5000K.

The screen shot is taken of the image as displayed in RawTherapee with basic editing (brightness +80, contrast +40).

The sky seems muddy/yellowish - something that becomes very clear if I move the image to my uncalibrated Samsung screen, where the blue seems much more to my memory.

It does not help
- to change the raw converter (Iridient or RawTherapee)
- to change the monitor calibration target from grey to contrast priority
- to change the camera Profile from my own to Iridients default

When I take screen shots to demonstrate the difference for this post,
there is no difference between them if displayed on the same monitor.

It helps to choose a D65 profile for the Eizo. In this case, the uncalibrated Samsung seems yellowish.

There was some problem that the Mac version of RawTherapee was limited in on-screen color rendition in some way, but the TIF displayed in PhotoLine is the same.

So how does this rhyme? And what should I do for future editing? And worse: with all the past editing, where I used the D50 pipeline?? I remember that I had to adjust the sky separately in some images - how will they print? (I don't print myself, so I can not easily check this).

Sigh!


Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 01, 2018, 03:42:41 pm
The shot is taken with a camera White Balance of 5000K (according to the menu on the a7r2), my monitor (Eizo CG243W) is calibrated to a target of D50, the ambient light in my room is by D50 Yuji lamps, daylight is excluded. The camera profile is created with DCamProf, the target shot with a Solux lamp run at 15 V to give something near 5000K.
Kind of meaningless as the camera isn't the right measurement device to define what is actually a large range of possible colors (CCT 5000K). And the only light source that produces D50 (an average of many measurements made over the world) comes from a source 93 million miles away from your Eizo. So no, it doesn't rhyme.
So, can you produce a rendering that you desire is the real question?
Title: Re: The sky is blue - or should be...
Post by: DP on May 01, 2018, 04:12:31 pm
...

care to post the raw file ?
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 01, 2018, 05:02:44 pm
Hi Andrew,
thanks for your reply.
> So, can you produce a rendering that you desire is the real question?

Tomorrow, I'll try to fiddle with the WB and Tint in RawTherapee (more extensively than I have done so far).

Hi DP
thanks for your reply.
The raw file is here:
https://www.dropbox.com/s/4r5p2futnilnt7f/_DSC3216%2A.ARW?dl=0
Title: Re: The sky is blue - or should be...
Post by: Doug Gray on May 01, 2018, 05:08:31 pm
Check to make sure you aren't blowing out the Red/Green channels. That will always decrease saturation in sky blues. For that matter, just applying the regular "S" shaped tone curve when creating the image will de-saturate as well.

There are many unknowns in the rest of the process which could impact it as well but the former should be checked.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 01, 2018, 05:10:56 pm
Check to make sure you aren't blowing out the Red/Green channels.
Not even close:
Title: Re: The sky is blue - or should be...
Post by: DP on May 01, 2018, 05:22:34 pm
Hi DP
thanks for your reply.
The raw file is here:
https://www.dropbox.com/s/4r5p2futnilnt7f/_DSC3216%2A.ARW?dl=0


once I get home to my A7R2 profile and NEC PA I will try to convert it myself, who knows may be I score "better" and if so I will share my data w/ you... or may be I will get the same bad skies... can't try right now while I am still toiling @ work, sorry

PS: on my office monitor I "see" (  ;D ) that Rodney's screenshot rawdigger displays more decent skies (w/ all the fine print about the said monitor)...
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 01, 2018, 05:27:02 pm
Andrew:
Wow! You have already done it for me!
The image is underexposed, I had to use a short shutter speed and forgot to increase the ISO.
The blue of the sky in your jpeg looks much better than my screen shot. How did you do it??
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 01, 2018, 05:30:48 pm
@DP
> once I get home to my A7R2 profile and NEC PA I will try to convert it myself, who knows may be I score "better" and if so I will share my data w/ you... or may be I will get the same bad skies... can't try right now while I am still toiling @ work, sorry

That's very kind; there is no haste.
Title: Re: The sky is blue - or should be...
Post by: DP on May 01, 2018, 05:30:57 pm
Andrew:
Wow! You have already done it for me!
The image is underexposed, I had to use a short shutter speed and forgot to increase the ISO.
The blue of the sky in your jpeg looks much better than my screen shot. How did you do it??

rawdigger has some profiles embedded in it in order to display the image ...
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 01, 2018, 06:18:05 pm
Andrew:
Wow! You have already done it for me!
The image is underexposed, I had to use a short shutter speed and forgot to increase the ISO.
So to continue if necessary  ;D , raising the ISO would have zero effect on exposure. Yeah, it's under exposed and there lies the beauty of a raw Histogram and RawDigger.
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 01, 2018, 06:41:43 pm
> raising the ISO would have zero effect on exposure.

Oops - yeah there was this thing about ISO-less cameras, I remember...Your post will remind me that I got me one of those...So the ISO setting can only be used to adjust visibility on the camera monitor.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 01, 2018, 07:03:30 pm
> raising the ISO would have zero effect on exposure.

Oops - yeah there was this thing about ISO-less cameras, I remember...Your post will remind me that I got me one of those...So the ISO setting can only be used to adjust visibility on the camera monitor.
Exposure is aperture and shutter speed to affect how much light (photons) striking the sensors or film. ISO is not an direct attribute of exposure.
Title: Re: The sky is blue - or should be...
Post by: DP on May 01, 2018, 09:03:30 pm
That's very kind; there is no haste.

so I tried - my simple general purpose matrix DCP profile alone does not get the skies to a good saturation with that raw file - I have to use either HSL sliders and/or calibration tab in ACR to get the skies as "blue" as you apparently want, sorry... probably you need to create a special profile optimized for blues
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 02, 2018, 02:17:38 am
...my monitor (Eizo CG243W) is calibrated to a target of D50...

The sky seems muddy/yellowish - something that becomes very clear if I move the image to my uncalibrated Samsung screen, where the blue seems much more to my memory.

It helps to choose a D65 profile for the Eizo. In this case, the uncalibrated Samsung seems yellowish.

I'm at a loss as to how you think you're going to get a proper looking blue sky with so many variances to the appearance of "neutral white" you've outlined with your editing workflow which you've admitted you prefer D50 display which isn't a neutral white.

Why not add more blue to the white balance in your image editor since D50 makes sky blue look muddy yellow.

On my calibrated to "neutral white" display the entire image looks a bit too green and the blue sky is a quite desaturated blue with more of a magenta tinge. I'm working on a similar daylight shot image where the sky HAS to have a huge magenta bias or else the entire scene looks a bit too green like your shot.

The first shot is the As Shot WB which I mistakenly left on Custom WB from sampling a D50 fluorescent tube off a white microwave oven which shifted the tint slider in ACR to +16 magenta. Unfortunately this wasn't getting rid of the green bias of the As Shot so I edited the WB to keep the magenta in the blue sky and force the shadows of the trees in the distant hill to look neutral because they didn't look blue or blue green.

Magenta is the invisible hue that is tough to edit properly and can't be quickly seen in nature but if not viewing on a neutral white display will play tricks on your eyes into seeing hues that were not in the original scene but still kinda' make it look right but something is off. It's maddening.

Title: Re: The sky is blue - or should be...
Post by: GWGill on May 02, 2018, 03:38:00 am
you've admitted you prefer D50 display which isn't a neutral white.
Umm, what ? D50 is certainly (one) definition of neutral. Anything sufficiently close to the black body or Daylight locus is neutral. It's the print standard for neutral!

As for what whether a particular display color temperature looks cool or warm, - that rather depends on how neutral and what color temperature other light sources around the display are, and how adapted to the screen white the observer is.

(I routinely run with my display set to D55, and it's certainly neutral.)

Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 09:07:14 am
Umm, what ? D50 is certainly (one) definition of neutral.
Indeed, that comment of Tim’s was out of far left field.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 10:21:09 am
Magenta is the invisible hue ....
What, seriously?
Title: Re: The sky is blue - or should be...
Post by: nirpat89 on May 02, 2018, 11:42:38 am
I think the whole picture is "hazy" which you can fix by using Levels.  The highlights are lacking in the picture so in the first Levels, I moved the slider to 225.  Moved the shadows slider a little as well.  Then the mid-tone slider to 0.60 which is what gives the blue sky.  The foreground got a little darker, so used a gradient mask.  The left side is slightly lighter than the right, I guess because of the direction of the Sun.  So added an another layer masking everything but the left corner which makes the sky even. 
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 02, 2018, 12:53:36 pm
Had the photographer(s) not interfered, I think a camera or a photo printing machine might have produced this appearance using “Auto” mode settings.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 01:36:44 pm
Not sure why someone is futzing around with an image that isn't the OPs, kind of pointless.
Producing a blue sky from the raw supplied isn't really rocket science:
Title: Re: The sky is blue - or should be...
Post by: sebbe on May 02, 2018, 02:24:13 pm
Not sure why someone is futzing around with an image that isn't the OPs, kind of pointless.
Producing a blue sky from the raw supplied isn't really rocket science:

As far as I understand it he is looking after the reason not how to turn the sky blue.

to OP: A lens can have quite an impact on colors. Your picture was shot with an old non sony lens over a mechanical adapter I suppose (no exif about the lens and aperture). And then there is quite som haze as other already mentioned. The sky I very bright then and this can also change the colors. I would add some points on tint towards magenta and also a few kelvins towards yellow. See below.

Reshoot it and use a gray card or LCC-plate to get the right white balance for the scene. Try your test test again.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 02:30:41 pm
As far as I understand it he is looking after the reason not how to turn the sky blue
How NOT to turn the sky blue? I produced a bluer sky. I can produce a lesser blue sky. With the OP's supplied raw. Under exposing any image isn't ideal, we've covered that. But even with the under exposed sky, making it more or less blue isn't rocket science.
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 02, 2018, 03:21:10 pm
Umm, what ? D50 is certainly (one) definition of neutral. Anything sufficiently close to the black body or Daylight locus is neutral. It's the print standard for neutral!

As for what whether a particular display color temperature looks cool or warm, - that rather depends on how neutral and what color temperature other light sources around the display are, and how adapted to the screen white the observer is.

(I routinely run with my display set to D55, and it's certainly neutral.)

I'm not doubting you think your display set to D55 looks neutral to you, but the OP has stated his display set to D50 makes the blue sky image he posted look muddy yellow which doesn't look that way on my display.

Does the blue sky sample image posted by the OP look muddy yellow to you on your D55 calibrated display?


That's the problem with folks associating a color temp number to some hue of neutral for display calibration. At some point the yellowish/orangish hue of D50 compared to D65 is going to contaminate certain colors such as blue sky because clearly ICC display profile matrices and/or LUTs aren't fixing it calibrating to D50 if blue skies look muddy yellow as the OP indicated.

It appears that we all need to stop thinking our display can represent real daylight and just make sure white and gray tones look neutral. Call it D50 or whatever. The number doesn't matter as evident in this thread.
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 02, 2018, 03:26:04 pm
Had the photographer(s) not interfered, I think a camera or a photo printing machine might have produced this appearance using “Auto” mode settings.

What is your point with the look you've given those screenshots? Are you saying "Auto" mode favors overly orangy yellow warm daylight? Or that they have a screwed up version of what D50 is suppose to look like?

I have never encountered any printer whose "Auto" mode rendered images that way. Or are you just being funny?
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 02, 2018, 03:30:23 pm
As far as I understand it he is looking after the reason not how to turn the sky blue.

to OP: A lens can have quite an impact on colors. Your picture was shot with an old non sony lens over a mechanical adapter I suppose (no exif about the lens and aperture). And then there is quite som haze as other already mentioned. The sky I very bright then and this can also change the colors. I would add some points on tint towards magenta and also a few kelvins towards yellow. See below.

Reshoot it and use a gray card or LCC-plate to get the right white balance for the scene. Try your test test again.

Perfectly rendered. You got the foliage shadow hues just right and the blue sky as well. But you didn't address why the OP is seeing the blue sky as muddy yellow. Anyone can render someone else's image to look right but that's not the OP's problem.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 03:38:40 pm
I'm not doubting you think your display set to D55 looks neutral to you...
You're not reading or comprehending the facts presented to you (again). You're again confused by color perception and color appearance! And you didn't read the facts:
D50 is certainly (one) definition of neutral. Anything sufficiently close to the black body or Daylight locus is neutral.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 03:39:56 pm
Anyone can render someone else's image to look right but that's not the OP's problem.
I'm pretty certain both concepts are wrong. Certainly the first is!
Title: Re: The sky is blue - or should be...
Post by: Doug Gray on May 02, 2018, 03:44:34 pm
I'm not doubting you think your display set to D55 looks neutral to you, but the OP has stated his display set to D50 makes the blue sky image he posted look muddy yellow which doesn't look that way on my display.

Does the blue sky sample image posted by the OP look muddy yellow to you on your D55 calibrated display?


That's the problem with folks associating a color temp number to some hue of neutral for display calibration. At some point the yellowish/orangish hue of D50 compared to D65 is going to contaminate certain colors such as blue sky because clearly ICC display profile matrices and/or LUTs aren't fixing it calibrating to D50 if blue skies look muddy yellow as the OP indicated.

It appears that we all need to stop thinking our display can represent real daylight and just make sure white and gray tones look neutral. Call it D50 or whatever. The number doesn't matter as evident in this thread.
Most likely the problem isn't the ICC display profiles but partial adaptation when using monitors with different whitepoints. It can take many minutes to get adapted when changing monitors or different whitepoints on the same one and if you switch using the same image then colors seem off. This gets a bit locked in one's mental image.  When switching whitepoints one should do other computer work for 10 minutes or so before looking at images. That's why it's best to stick with just one whitepoint. Most select a monitor white point that most closely matches a near hard proof station so that physical prints will look close to the same on the monitor using soft proof.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 03:50:43 pm
Most likely the problem isn't the ICC display profiles but partial adaptation when using monitors with different whitepoints. It can take many minutes to get adapted when changing monitors or different whitepoints on the same one and if you switch using the same image then colors seem off. This gets a bit locked in one's mental image.  When switching whitepoints one should do other computer work for 10 minutes or so before looking at images. That's why it's best to stick with just one whitepoint. Most select a monitor white point that most closely matches a near hard proof station so that physical prints will look close to the same on the monitor using soft proof.
What Tim doesn't seem to understand in GWGill's factual post is that what looks/appears neutral and is neutral are not the same. If he puts on rose color glasses, anything he thinks is neutral (D55, D50 etc) while being neutral doesn't appear neutral. What Tim wrote was simply wrong: you've admitted you prefer D50 display which isn't a neutral white.
The reason there's so much ignorance on the subject of color management, is that those who have it are so eager to regularly share it! - The Digital Dog
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 02, 2018, 03:50:52 pm
Most likely the problem isn't the ICC display profiles but partial adaptation when using monitors with different whitepoints. It can take many minutes to get adapted when changing monitors or different whitepoints on the same one and if you switch using the same image then colors seem off. This gets a bit locked in one's mental image.  When switching whitepoints one should do other computer work for 10 minutes or so before looking at images. That's why it's best to stick with just one whitepoint. Most select a monitor white point that most closely matches a near hard proof station so that physical prints will look close to the same on the monitor using soft proof.

You still didn't explain why the OP is seeing the blue sky as a muddy yellow. He states clearly that the initial preview on his Eizo (he's already adapted to) and is his go to reference for neutral D50 as an editing workstation says the blue sky look muddy yellow. That's a huge shift that can't be explained with adaptation. I have a mix of different hues of light all around my workstation display and I NEVER see blue skies look that way in ANY of my images.

There's something messed up with the OP's display if it makes blues skies look that bad!
Title: Re: The sky is blue - or should be...
Post by: Doug Gray on May 02, 2018, 03:55:31 pm
You still didn't explain why the OP is seeing the blue sky as a muddy yellow. He states clearly that the initial preview on his Eizo (he's already adapted to) and is his go to reference for neutral D50 as an editing workstation says the blue sky look muddy yellow. That's a huge shift that can't be explained with adaptation. I have a mix of different hues of light all around my workstation display and I NEVER see blue skies look that way in ANY of my images.

There's something messed up with the OP's display if it makes blues skies look that bad!

Could be something wrong in his process. I opened the RAW file in Photoshop and the sky looks pretty much what I would expect and I use D50 whitepoint.  If that happened to me I would measure the Lab reading from the monitor and compare it to samples from the image in the same area.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 03:55:52 pm
I have a mix of different hues of light all around my workstation display and I NEVER see blue skies look that way in ANY of my images.
You've apparently got color perception issues because you told us that Magenta 'is an invisible hue'. That's of course simply nonsensical to anyone here who actually understands color.
Title: Re: The sky is blue - or should be...
Post by: Doug Gray on May 02, 2018, 04:06:25 pm
You've apparently got color perception issues because you told us that Magenta 'is an invisible hue'. That's of course simply nonsensical to anyone here who actually understands color.

I guess you just haven't profiled a CYK printer recently.   ;)
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 02, 2018, 04:06:29 pm
Could be something wrong in his process. I opened the RAW file in Photoshop and the sky looks pretty much what I would expect and I use D50 whitepoint.  If that happened to me I would measure the Lab reading from the monitor and compare it to samples from the image in the same area.

That might explain it, Doug. But an Eizo is a pretty reliable display and the OP isn't a slouch when it comes to wanting to be precise about his calibration and profiling so I'm thinking it might be attributed to what the Raw converter is doing under the hood with how it renders ICC managed previews. Maybe he's only seeing a yellowish hue for that particular blue and the rest looks normal. But it is a screengrab he posted and I don't see any muddy yellow.

And to any nimrod that posts the plankian locus showing where D50 falls within the area of neutrality, I've got about 5 different versions of this locus and it places D50 way over in the warm region, so just stop posting those useless idiotic, worthless maps. Just looking at how different all of them are to what is warm verses cool makes me want to ring the neck of a the color scientists that make these stupid maps.
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 02, 2018, 04:07:41 pm
Uff what a discussion I triggered! Thanks to all who chimed in. I'll present the result of my own fiddling before I study your posts more closely.
There is no way I can achieve a satisfactory result in RawTherapee. I get my best result with an adjustment layer 'Color Balance' in PhotoLine. However, the histogram becomes jaggy. 

Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 02, 2018, 04:14:49 pm
I guess you just haven't profiled a CYK printer recently.   ;)

I'm glad you brought that up because it is an invisible hue when when mixed with a bluish looking daylight image especially with a magenta hued blue sky. How much yellow should be seen in green foliage lit by a noon day sun on a clear day? How warm does the sun make natural objects look no matter whether they are cool or warm toned? To get a convincing daylight appearance it helps to take note how much magenta is in sky blue.

For example stare at the second image I posted (not the flotube WB top version) and then look at a neutral gray area on your display. What hue has it turned into? On my display it makes ACR's neutral R=G=B surround take on a muddy greenish yellow tint. Not too pronounced but very subtle. But note you can't really see magenta in the green foliage or warm concrete. Sample the skin tones and the Lab reading favor a orangish yellow hue and have tint slider in ACR set to +30.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 04:18:55 pm
I guess you just haven't profiled a CYK printer recently.   ;)
Oh I have. Doesn’t back up Tim’s ridiculous and utterly wrong idea that Magenta is an invisible hue! Where does he come up with these flat earth ideas?
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 02, 2018, 04:20:11 pm
That magenta crack was by Andrew. Sorry, Doug, my mistake. It's clear Andrew hasn't edited very many daylight images seeing he isn't a photographer any longer and is just a technology writer.

Magenta is a nasty hue especially when rendering in ACR using Knoll's color engine which provides a very pure hue of this magenta that if applied in the right amount creates perfect renditions of blue skies that I take visual notes on when I photograph my local park. Daylight changes hue in this town and there are a myriad of beautiful blue sky color I want to capture and faithfully render.
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 02, 2018, 04:24:08 pm
Uff what a discussion I triggered! Thanks to all who chimed in. I'll present the result of my own fiddling before I study your posts more closely.
There is no way I can achieve a satisfactory result in RawTherapee. I get my best result with an adjustment layer 'Color Balance' in PhotoLine. However, the histogram becomes jaggy.

Hening, are you seeing how cyanish green that entire image looks or are you still seeing the blue sky a muddy yellow? I'm not seeing it in Firefox browser which is color managed.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 04:27:06 pm
Sorry, Doug, my mistake.
You made so many! Just today.

Quote
It's clear Andrew hasn't edited very many daylight images seeing he isn't a photographer any longer and is just a technology writer.
Magenta is a nasty hue especially when rendering in ACR using Knoll's color engine which provides a very pure hue of this magenta that if applied in the right amount creates perfect renditions of blue skies that I take visual notes on when I photograph my local park. Daylight changes hue in this town and there are a myriad of beautiful blue sky color I want to capture and faithfully render.
Rubbish and more rubbish. How can you edit an invisible hue in ACR or anywhere else. Such comments are compelling reasons not to take you at all seriously again. Par for the course for someone who isn't a professional photographer or a technically correct writer. That’s where we differ Tim!
Title: Re: The sky is blue - or should be...
Post by: Doug Gray on May 02, 2018, 04:28:10 pm
I'm glad you brought that up because it is an invisible hue when when mixed with a bluish looking daylight image especially with a magenta hued blue sky. How much yellow should be seen in green foliage lit by a noon day sun on a clear day? How warm does the sun make natural objects look no matter whether they are cool or warm toned? To get a convincing daylight appearance it helps to take note how much magenta is in sky blue.

For example stare at the second image I posted (not the flotube WB top version) and then look at a neutral gray area on your display. What hue has it turned into? On my display it makes ACR's neutral R=G=B surround take on a muddy greenish yellow tint. Not too pronounced but very subtle. But note you can't really see magenta in the green foliage or warm concrete. Sample the skin tones and the Lab reading favor a orangish yellow hue and have tint slider in ACR set to +30.

How much a color appears to change when adding/subtracting other RGB colors depends on the color. The ones that affect luminance the most, such as yellow, make a bigger difference because adding yellow increases luminance a lot. The other end of the scale is blue. You can add quite a lot of blue without changing luminance so the effect adding blue to, say a strong yellow is quite low, It mostly results in lower saturation.  Magenta has bigger effect on luminance than blue but is still relatively small. So adding a bit of magenta to greens mostly desaturates the greens. OTOH, adding greens to a magenta color, or yellow to a blue color, will produce marked increases in luminance.

But that's in RGB colorspaces. In L*a*b*, you can hold luminance constant and add/subtract colors on opposite sides of the a*b* center (neutral by definition). You will see very different results doing that.

Title: Re: The sky is blue - or should be...
Post by: Alexey.Danilchenko on May 02, 2018, 04:31:16 pm
As far as I understand it he is looking after the reason not how to turn the sky blue.

Reason - rubbish profile. What comes with ACR (profiles) is for most part of it not good so it may be beneficial to build and tune your own profile.
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 02, 2018, 04:35:37 pm
What is your point with the look you've given those screenshots?

My point was to offer examples of how far off base the originals are from what typical imaging software would render the scenes as using common aim points of black, neutrals, white, and determining a white balance.

Are you saying "Auto" mode favors overly orangy yellow warm daylight? Or that they have a screwed up version of what D50 is suppose to look like?
I think in your Reply 34 you mention D50 as "way over in the warm region." Do you not?

I have never encountered any printer whose "Auto" mode rendered images that way. Or are you just being funny?

You have encountered those printers but you just don't realize it.


So, after my simple button-click exercise on my end, IMO the OP's sky was never as blue as he believes and other's renderings are as underexposed as the first. Look at the unusual histograms. Also, Tim's processing of his photo leaves a lot to be desired. But, just my opinion.


Title: Re: The sky is blue - or should be...
Post by: TonyW on May 02, 2018, 04:45:40 pm
Uff what a discussion I triggered! Thanks to all who chimed in. I'll present the result of my own fiddling before I study your posts more closely.
There is no way I can achieve a satisfactory result in RawTherapee. I get my best result with an adjustment layer 'Color Balance' in PhotoLine. However, the histogram becomes jaggy.
Hening,
Is there any reason why your first image has an embedded monitor profile?

As to RawTherapee I can see no reason why a good result cannot be achieved quite simply.  In this case using RT the attached adjusted file only had Auto and +10 saturation (and I normally do not use/like Auto.

Are you using the current version of RT - this might make a difference?

Wait a few seconds for image to change

Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 02, 2018, 04:46:07 pm

I think in your Reply 34 you mention D50 as "way over in the warm region." Do you not?

Yes, I did say that but D50 in reference to actual daylight doesn't have that much of highly saturated version of orangy yellow as shown in your renderings. 

Also, Tim's processing of his photo leaves a lot to be desired. But, just my opinion.

Again, another unhelpful comment. Care to be specific on what you find undesirable about the look of the image I posted I specifically chose to represent an accurate rendition (not "Pleasing" rendition) of a daylight scene taken in my local park.

Can you see magenta in the foliage shadows or highlights? In the skin tones? The Lab readings indicate not much magenta is in those skin tones but you can really see it in the blue sky and clouds. ACR tint slider was set at +30. That's a lot of magenta.

Come on Stephen! Be helpful. No one's interested in your opinions.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 04:51:35 pm
Come on Stephen! Be helpful. No one's interested in your opinions.
Again speaking for others (everyone) illustrating the pot calling the kettle black.
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 02, 2018, 04:52:26 pm
Hening,
Is there any reason why your first image has an embedded monitor profile?

As to RawTherapee I can see no reason why a good result cannot be achieved quite simply.  In this case using RT the attached adjusted file only had Auto and +10 saturation (and I normally do not use/like Auto.

Are you using the current version of RT - this might make a difference?

Wait a few seconds for image to change

Hening still isn't explaining why the blue sky in the Raw Therapee screengrab looks a muddy yellow as he stated in his OP. Tony, did he message you and tell you he still see this no matter what Raw settings he uses? He's not answering what is causing the muddy yellow blue sky.
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 02, 2018, 05:06:23 pm
Here's the skin tone lab reading and ACR white balance slider settings. You can now see on the close up the effects of lots of magenta in the form of an "optical brightener/purplish iridescent " effect on the woman's black hair but her skin does not look pink, purple or reddish. This is why I said magenta is the invisible hue in actual daylight with the sun high in the sky. Not the same for the golden hour.

How much magenta is too much is subjective of course.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 05:13:30 pm
Here's the skin tone lab reading and ACR white balance slider settings.
No, it's not. You still have no idea what the Digital Color Meter is showing and how!

It's not measuring anything. It is taking two or three bits of information:

1. The color that an app is actually outputting to a pixel. i.e. an RGB level.
2. The colorspace that the app says should be used for that pixel for ColorSync to correctly display it (defaults to sRGB if the app doesn't specify).
3. The ICC profile associated with the display.

IF you knew how to use ACR, you'd know how to set it for Lab read-outs without futzing with the Digital Color Meter you've shown here today and pasted below, with ACR set clearly to RGB. Would you like to learn how to use ACR to show you the Lab values of the actual data within ACR or continue to confuse yourself with the numbers that are divorced from the actual data?
Probably the later..... :-\
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 05:18:37 pm
How much magenta is too much is subjective of course.
Only if it's visible.  :P
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 02, 2018, 05:44:18 pm
Still ignoring nimrod.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 05:47:03 pm
Still ignoring nimrod.
"The highest form of ignorance is when you reject something you don't know anything about". -Wayne Dyer

Modern Nīmrōd, Tiberian Nīmrōḏ, Aramaic: ܢܡܪܘܕ‎, Arabic: النمرود‎ an-Namrūd), a biblical figure described as a king in the land of Shinar (Assyria/Mesopotamia), was, according to the Book of Genesis and Books of Chronicles, the son of Cush, therefore the great-grandson of Noah. The Bible states that he was "a mighty hunter before the Lord [and] .... began to be mighty in the earth".[2]
Title: Re: The sky is blue - or should be...
Post by: mouse on May 02, 2018, 05:49:36 pm
So to continue if necessary  ;D , raising the ISO would have zero effect on exposure. Yeah, it's under exposed and there lies the beauty of a raw Histogram and RawDigger.

Apologies for sticking my oar into this thread, but this reply has me confused.  It has been my belief (and experience IIRC) that increasing the ISO (while not, strictly considered, an exposure parameter) has a very direct effect on the raw Histogram as displayed in RawDigger. 
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 06:40:35 pm
Apologies for sticking my oar into this thread, but this reply has me confused.  It has been my belief (and experience IIRC) that increasing the ISO (while not, strictly considered, an exposure parameter) has a very direct effect on the raw Histogram as displayed in RawDigger.
See: https://www.rawdigger.com/howtouse/rawdigger-histograms-overexposure-shapes (https://www.rawdigger.com/howtouse/rawdigger-histograms-overexposure-shapes)
Different cameras, even if based on the same sensor, may render extreme highlights around the clipping point differently; and differently, even with different values of clipping points, depending on ISO setting. It is important to recognize the look and calculate the practical clipping point, which is not always the same as the maximum raw value. Here we will try to demonstrate the typical “looks” of the histogram of the clipping zone.
Title: Re: The sky is blue - or should be...
Post by: TonyW on May 02, 2018, 06:43:17 pm
Hening still isn't explaining why the blue sky in the Raw Therapee screengrab looks a muddy yellow as he stated in his OP. Tony, did he message you and tell you he still see this no matter what Raw settings he uses? He's not answering what is causing the muddy yellow blue sky.
Tim, I am not seeing the muddy yellow sky he is seeing either in Firefox, PS or Raw Therapee from the raw file or the screen grab in the first post (at least from memory-I am away from PC now)

I have had no messages telling me what he is seeing

Selecting areas with the PS colour picker indicated sky hue to be grey/blue.

My gut feeling is that the issue may be a poor monitor profile causing the yellow muddy tones and leading to potential over correction which looks to be the case with a corrected image in reply#35; appears too blue overall to me

In any case there is no reason I can see that suggests he will not get a pleasing rendering from RT (which may be very different to my play!) or as Andrew has shown in ACR.  Assuming of course an accurate monitor profile

Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 02, 2018, 06:57:15 pm
I have had no messages telling me what he is seeing
Nobody here but the OP does (and Tim of course), and speaking for everyone who's not sitting in front of his display is OK in this context. We simply have no idea what he's seeing but that doesn't stop someone from suggesting what he's seeing as he uses English words (muddy/yellowish, Magenta that isn't invisible, blue) mean and appear like. Utter speculation. And even the numbers provided by someone is bogus, not that numbers tell us what a color appears like, certainly without color management going full circle to needing to be in front of the OP's display with him.
Title: Re: The sky is blue - or should be...
Post by: GWGill on May 02, 2018, 08:50:43 pm
I'm not doubting you think your display set to D55 looks neutral to you, but the OP has stated his display set to D50 makes the blue sky image he posted look muddy yellow which doesn't look that way on my display.
Sounds like your display isn't reproducing in an sRGB like EOT then.
Quote

Does the blue sky sample image posted by the OP look muddy yellow to you on your D55 calibrated display?

Yes it does, because that's the color it is (in sRGB space). It's low saturation :- b* is -9.

And it looks (subjectively) the same on my D65 white point Macbook Pro retina display.

Quote

That's the problem with folks associating a color temp number to some hue of neutral for display calibration. At some point the yellowish/orangish hue of D50 compared to D65 is going to contaminate certain colors such as blue sky because clearly ICC display profile matrices and/or LUTs aren't fixing it calibrating to D50 if blue skies look muddy yellow as the OP indicated.

Umm. what ???
 
Even in a mixed WP adaptation situation (something that is hard to organize - the display tends to dominate your perception if it is large and you are concentrating on it), a WP shift will alter hue perception, but won't alter saturation.


Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 03, 2018, 07:30:28 pm
I highly appreciate all the concern I got for my problem! Now I'll try to reply to (some of) your posts.
First off, I made 2 mistakes in my initial statement:
1-My camera profile was not shot by me - I used the target shot kindly supplied by Imaging-Resource.com. Unfortunately, I can't retrieve the link to it, nor the raw file on my Mac.

2- my initial basic editing in RawTherapee was Lightness +40, Contrast +80, not the other way round as I posted.

Now some comments

@Andrew
Yes I'm aware of that WB only refers to the blue-yellow balance and neglects the magenta-green balance. But the 5000K camera WB complies with my fresh memory in most cases - why not in this, and why the sky in particular? This is not a scene with a tricky lighting - it's about-noon daylight with a sunny sky, with moving clouds.

@DP, reply#13 on May 01, 2018

Thank you for your effort.

@Tim, reply # 14
Of the 2 versions of your park scene, if viewed one at a time, both look credible to me. If viewed simultaneously, I would prefer the 1st one. The sky looks more credible to me, and I would find that more important than neutral shadows. Why should shadows be neutral?

@nirpat89, reply #18
Your sky looks VERY good to me! I will later have to try if I can duplicate it using your method. I'm not familiar with Levels. - The fore- and middle ground I find too dark. So if I succeed duplicating your sky, I'll apply it using a mask.

@ Stephen Ray, reply #19
In your rendering of my image, the sky looks even worse, and the trees are all too yellow. I'm afraid I will have to go on interfering...

@andrew, reply #20
That sky is blue at least, and it looks to me like it would be good if lightened.

@sebbe, reply #21
> As far as I understand it he is looking after the reason not how to turn the sky blue.
Yes, mainly. Of course I want to cure this image also.
Yes the lens was a 135 mm Zuiko, which has a greenish tint - not a yellow one.
> I would add some points on tint towards magenta and also a few kelvins towards yellow. See below.
No, on the contrary...! I think the sky needs more blue/cyan, not yellow, and not at all magenta...Unlike Tim in the next post, I find the foliage all too yellow in your rendering. I find my own image quite OK in THAT regard. That is the problem - the SKY is off - why?

@Doug Gray reply #28
> Most likely the problem isn't the ICC display profiles but partial adaptation when using monitors with different whitepoints.
This has to be considered. But now that I have gotten all these replies I can compare them to my initial rendering on the same monitor, and the problem is the same. Some have provided better renderings of the sky, but at the expense of the foliage, so they would have to be applied separately to the sky.

@ Doug Gray reply #31
> If that happened to me I would measure the Lab reading from the monitor and compare it to samples from the image in the same area.
I tried it using the Digital Color Meter, but I'm not familiar with Lab, so I don't know what to make of the results:
image sky left side: L*82.26, a* -2.96, b* -9.70
screen area: L*100 a*0.00 b*0.00

@Tim, reply #39
> Hening, are you seeing how cyanish green that entire image looks
Yes I do, but I find the sky more to my memory, so I would have to apply that rendering to the sky only.

@Alexey.Danilchenko, reply #42
> Reason - rubbish profile. What comes with ACR (profiles) is for most part of it not good so it may be beneficial to build and tune your own profile.
Alexey, I don't use Adobe profiles. As I stated initially, I built my own with DCamProf, in this case using a target shot supplied by Imaging-Resource.com.
Yes I also suspect the profile - I just don't know how to improve it.

@Stephen Ray reply #43
> IMO the OP's sky was never as blue as he believes
That is certainly a possible bias to be considered. I am aware of that the sky is "blue" near the zenith, but not so much near the horizon, where the blue fades out. But on a day like this, it does not become muddy or yellowish.

@TonyW, reply#44
Uff! That rendering seems perfect to me! Theoretically unsatisfactory that 'Auto' does it. I'll try to duplicate it and try to find out what 'Auto' does.

> Is there any reason why your first image has an embedded monitor profile?
I would think it is because it's a screen shot?

The version of RT I used was 5.3-602.

@ Tim, reply #47
> Hening still isn't explaining why the blue sky in the Raw Therapee screengrab looks a muddy yellow as he stated in his OP. Tony, did he message you and tell you he still see this no matter what Raw settings he uses? He's not answering what is causing the muddy yellow blue sky.

I don't understand. If I knew why that sky looks the way it does, I would not need to bother you guys with my question - ?

@ TonyW, reply #55
> My gut feeling is that the issue may be a poor monitor profile
The monitor profile is created with the Eizo Color Navigator and an i1 Display, to the target as mentioned.

So next stop will be trying to duplicate Tony's rendering in RT - tomorrow!
Good night - and thanks a lot!




Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 03, 2018, 07:41:32 pm
@Andrew
Yes I'm aware of that WB only refers to the blue-yellow balance and neglects the magenta-green balance. But the 5000K camera WB complies with my fresh memory in most cases - why not in this, and why the sky in particular? This is not a scene with a tricky lighting - it's about-noon daylight with a sunny sky, with moving clouds.
My point was that the numbers are kind of meaningless when you get them from a camera which isn't the correct tool for measuring and reporting a correlated color temperature in Kelvin. That's a range of possible colors for one. IOW, that your camera 'states' CCT 5000K doesn't mean that's what the illuminant is. If you had say a Spectrophotometer and the right software, the reported values would be more valid but in no way does that mean your display is producing that color value, or that the two MUST match if you could get two such measurements.
See:
http://digitaldog.net/files/22Thecolorofwhite.pdf (http://digitaldog.net/files/22Thecolorofwhite.pdf)

Quote
That sky is blue at least, and it looks to me like it would be good if lightened.
Easy to do and one of the problems editing someone else's image. The data (raw) is there, and you should be able to render a blue sky as you desire.
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 03, 2018, 08:00:49 pm
I'm glad you brought that up because it is an invisible hue when when mixed with a bluish looking daylight image especially with a magenta hued blue sky. How much yellow should be seen in green foliage lit by a noon day sun on a clear day? How warm does the sun make natural objects look no matter whether they are cool or warm toned? To get a convincing daylight appearance it helps to take note how much magenta is in sky blue.

Not a high-end camera using "P" mode (auto), kit lens, hand-held, white balance "As Shot", one-click "auto" button for color, color checker in the scene for reference.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 03, 2018, 08:09:26 pm
Not a high-end camera using "P" mode (auto), kit lens, hand-held, white balance "As Shot", one-click "auto" button for color, color checker in the scene for reference.
Indeed but before even going to such proof of concept, which was indeed more proof, the silly 'idea' that Magenta is an invisible hue is simply, well super silly. Simply examine the definition of hue:
Hue is one of the main properties (called color appearance parameters) of a color (https://en.wikipedia.org/wiki/Hue)
If it's a color, it can't be invisible. Nor, as Tim suggests, can editing something invisible be subjective (how do you subjectively edit something invisible?). Just one more example of his color science fiction. Instead of color science (https://arstechnica.com/science/2009/02/yes-virgina-there-is-a-magenta/).
Title: Re: The sky is blue - or should be...
Post by: nirpat89 on May 03, 2018, 08:29:04 pm
@nirpat89, reply #18
Your sky looks VERY good to me! I will later have to try if I can duplicate it using your method. I'm not familiar with Levels. - The fore- and middle ground I find too dark. So if I succeed duplicating your sky, I'll apply it using a mask.
Yeah I didn't spent too much time trying to perfect the fore- and middle grounds.  You can do a Curves or Brightness/Contrast layer with a reversed gradient mask to fine tune those areas.   I am not familiar with RawTherapy but I am sure you should be able to manipulate the histogram towards a similar final outcome as the Levels adjustment in Photoshop. 

:Niranjan.
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 03, 2018, 09:24:49 pm
I'm not familiar with Levels.

Really Hening?
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 03, 2018, 10:06:11 pm
Common example of memory color being “a perfectly blue sky the day of photography.”

Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 03, 2018, 10:15:23 pm
Magenta – When you need invisible fire hydrants.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 03, 2018, 10:33:11 pm
Magenta – When you need invisible fire hydrants.
It matches the invisible magenta patch on the Macbeth quite well!  >:(
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 03, 2018, 11:49:42 pm
It matches the invisible magenta patch on the Macbeth quite well!  >:(

I think it would be interesting to learn from the decision maker how they arrived at this color for their hydrants. Maybe simply because they know the color easily stands out against the opposite color of the green lawn. Hydrants in my neighborhood are now white and appear to blend with the surroundings. I have no idea what those decision makers are thinking but I often notice cars parked in front of the white hydrants.
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 04, 2018, 12:10:22 am
Example of letting the camera use automatic mode for balancing white and exposure of a backlit scene resulting in perceptually natural shadows as I recall. No modifications were made via processing in Lightroom.
Title: Re: The sky is blue - or should be...
Post by: Czornyj on May 04, 2018, 04:06:02 am
"The problem with restricting maximum brightness to 100 nits (as in TV and Blu-ray) is that the brighter the color, the closer it becomes to white, so bright colors become less saturated. For example, the brightest saturated blue on an ordinary display is a mere 7 nits, so a blue sky will never be as bright and saturated as it should be."
https://www.dolby.com/us/en/technologies/dolby-vision/dolby-vision-white-paper.pdf

see p.4 - Hunt effect:
http://rit-mcsl.org/fairchild/PDFs/AppearanceLec.pdf

"Many people erroneously think of a photograph as an “exact” reproduction of a scene. The reality is that light levels in a natural scene can’t be reproduced using any current technology and certainly not in a print."(...)
"As photographers, our job is to interpret the scene as a print. We must make the decisions about what to keep and what to throw away. The photographic print is limited. To compensate for those limitations, we must enhance and discount portions of our image to create a photographic print that evokes our original perception. The raw workflow allows us to express our artistic vision.
The scene is our message, the photograph our media, and rendering is the art."
http://lumita.com/site_media/work/whitepapers/files/pscs3_rendering_image.pdf
Title: Re: The sky is blue - or should be...
Post by: TonyW on May 04, 2018, 06:54:00 am
....
@TonyW, reply#44

> Is there any reason why your first image has an embedded monitor profile?
I would think it is because it's a screen shot?

The version of RT I used was 5.3-602.
...
Coming from Windows background I was not aware that Mac OS embedded the monitor profile, so I guess my question seemed odd?

FWIW, Windows 10 Screenshot
Save an image as PNG.  PS gives a warning; "The RGB document "Screenshot(1).png" has a file format that does not support embedded color profiles" plus the option to assign a profile or Leave as is (don't color manage)
Using the Windows inbuilt Snipping tool will save an image automatically without an embedded profile


Realising that I was using an older version of RT I changed today to the newest v5.4 (Win 10).  Dragging your raw into that initially produced a much brighter image (clipped) as it added a tone curve (film).  Setting Tone curve to standard and using the method in my first post seems to produce the same result.  Hope that helps
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 04, 2018, 03:56:15 pm
Example of letting the camera use automatic mode for balancing white and exposure of a backlit scene resulting in perceptually natural shadows as I recall. No modifications were made via processing in Lightroom.

Stephen, thanks for posting all those examples. It confirms that not all camera's UV/IR filters are the same. I can never get the warm (slightly reddish looking) shadows in your shots from my 2006 Pentax DSLR shooting Raw which has been stated in Pentax forums has a Sony CCD sensor with very thin filters which produces overly reddish orange mids to highlights and overly bluish shadows shooting daylight scenes with incamera AWB. I can fix it in ACR 6.7 but then I have to use Split Tone quite often or else my images show an overall slightly greenish bias as shown in my first example. This is when I discovered the magenta slider can do a better job without affecting the rest of the memory colors.

I have to say your Xrite CC chart doesn't look too accurate to my daylight shot chart (accurate according to its Lab numbers) but then I'm assuming you weren't going for accuracy. Your camera reproduces daylight scenes quite different from my camera edited or unedited.

Hening's overly cyan/green daylight shot is not anywhere close to looking like it's lit by the sun but if he neutralizes the WB it'll make it look too warm since he's indicated the blue sky already looks a muddy yellow. That's messed up.

I'm wondering if the Eizo's WB calibration is set within the display's internal hardware LUTs which would not show up in a screengrab which is created straight off the 8 bit video card frame which has no WB curves applied.
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 04, 2018, 04:09:18 pm
"The problem with restricting maximum brightness to 100 nits (as in TV and Blu-ray) is that the brighter the color, the closer it becomes to white, so bright colors become less saturated. For example, the brightest saturated blue on an ordinary display is a mere 7 nits, so a blue sky will never be as bright and saturated as it should be."
https://www.dolby.com/us/en/technologies/dolby-vision/dolby-vision-white-paper.pdf

see p.4 - Hunt effect:
http://rit-mcsl.org/fairchild/PDFs/AppearanceLec.pdf

"Many people erroneously think of a photograph as an “exact” reproduction of a scene. The reality is that light levels in a natural scene can’t be reproduced using any current technology and certainly not in a print."(...)
"As photographers, our job is to interpret the scene as a print. We must make the decisions about what to keep and what to throw away. The photographic print is limited. To compensate for those limitations, we must enhance and discount portions of our image to create a photographic print that evokes our original perception. The raw workflow allows us to express our artistic vision.
The scene is our message, the photograph our media, and rendering is the art."
http://lumita.com/site_media/work/whitepapers/files/pscs3_rendering_image.pdf

I agree that photography can be an interpretive artform but I've gotten pretty darn close to reproducing daylight scenes in my locale as it appears to me despite the limitations of my old DSLR. In addition I've found photos posted of daylight scenes over in Photo.net's No Words forum from non-professional photographers come really close, better than my camera.

I have a background in photo realistic painting and have extended experience mixing colors made from various pigments and dyes. I know what light does to natural memory colors. I do believe the limitation for not being able to get very close to representing any natural color captured with a digital camera shooting Raw is mainly the photographer's fault.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 04, 2018, 04:14:25 pm
I have to say your Xrite CC chart doesn't look too accurate to my daylight shot chart (accurate according to its Lab numbers)
Your Lab numbers are bogus for one.... Or you don't understand them....
Next, it's rather clear viewing an sRGB image of Stephen's (lawn and lake shot, post #61) that the Macbeth and the scene is brighter than a synthetic Macbeth, the largest differences are in Lstar. If we examine aStar and bStar of the synthetic Macbeth purple patch (you know Tim, that invisible color), the deltaE differences between his shot and the Macbeth is pretty darn small: 3.13 in fact!
The aStar value of that patch should be 50, the bStar should be -13. The sRGB image produces an aStar of 54, a bStar of -20. Normalize the scene brightness and you get a very small dE. Now darker the scene CORRECTLY to get an Lstar to 51 of that 'invisible' magenta patch, the aStar remains the same, and bStar moves to 56, the deltaE is a whopping 3.21dE. DAMN close!
Need we go over the other 23 'visible' hues in his shot or is the 'invisible purple' which is a mere 3.13 dE difference enough colorimetric facts from some to ignore?
Quote
but then I'm assuming you weren't going for accuracy
Yes, you're again assuming and yes, you're wrong about his capture.  ::)
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 04, 2018, 04:23:08 pm
Marcin,

Why can't a DSLR shooting Raw interpret a scene as I see it? How do you separate interpretation from what the photographer saw when the technology won't give the photographer what he wants which is what he saw?

For example the image example below shows what I term fluorescing of green foliage by the the sun just above horizon. The one on the left is the default Raw and the one the right is my edited version according to what I saw. Is that artistic interpretation or an attempt at reproduction of the scene?
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 04, 2018, 04:23:46 pm
Coming from Windows background I was not aware that Mac OS embedded the monitor profile, so I guess my question seemed odd?
Depends on what is making the screen capture. Indeed, if you use the built in screen capture functionality from Apple, the display profile is embedded which makes sense. I use Snapz Pro which produces an untagged doc which I don't like but the product has other functionality I need. So I assign the display profile and convert to sRGB if I wish to post on the web. FWIW, I use a product on the Mac called Hazel which can keep watch of folders I specify and tag or convert the images automatically.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 04, 2018, 04:26:30 pm
Why can't a DSLR shooting Raw interpret a scene as I see it?


Seriously? This is what raw data appears as:

(http://www.digitaldog.net/files/raw.jpg)


And you're still massively confused between color appearance and color perception or the fact that these cameras suffer metameric errors as they don't follow the Luther Ives condition.
Read, learn, THEN post:
http://dougkerr.net/Pumpkin/articles/Metameric_Error.pdf (http://dougkerr.net/Pumpkin/articles/Metameric_Error.pdf)
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 04, 2018, 04:33:55 pm
Still ignoring nimrod.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 04, 2018, 04:38:08 pm
Still ignoring nimrod.
But others are not ignoring your misinformation and confusion!
Tim, you've been very productive in the last 48 hours, let's see what your readers have learned other than, maybe don't be a reader of your posts. You appear mostly a glutton for punishment. Quite an accomplishment for just a day posting here!

Magenta is the invisible hue...

Invisible, then we are told editing Magenta is subjective.

D50 display which isn't a neutral white.
Wrong and corrected by a fellow who is the author of ArgyllCMS & ArgyllPRO ColorMeter. What color management products did Tim author?

And to any nimrod that posts the plankian locus showing where D50 falls within the area of neutrality, I've got about 5 different versions of this locus and it places D50 way over in the warm region, so just stop posting those useless idiotic, worthless maps.
He doesn't understand what the CIE chromaticity diagram is and what the Planckian locus (notice his misspelling) is or what it means or what GWGill tried to explain to him.

Here's the skin tone lab reading and ACR white balance slider settings.
He doesn't know how to set ACR to provide Lab values, nor understand the Lab values from the Digital Color Meter do not tell us about the underlying image data in ACR.

Still ignoring nimrod.
He doesn't understand that a nimrod is a king and mighty hunter!

It's clear Andrew hasn't edited very many daylight images seeing he isn't a photographer any longer and is just a technology writer.
He doesn't understand what a professional photographer is nor what a technology writer is. Tim, let's trade photo client lists here; I'll start, here are some of my clients who paid me to make photographs:

Corporate Annual Report and Advertising photography specializing in people. Clients included Apple, GTE, Forbes, Microsoft, Smart and Final, Disney, Mrs Gooch’s (they became Whole Foods), Epson, the LAOOC.

Do tell us about your photography clients, do attempt to be factual as it should be easier than writing about color, a subject you seem the need to study a lot more and write a lot less about.
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 04, 2018, 06:51:16 pm
I have to say your Xrite CC chart doesn't look too accurate to my daylight shot chart (accurate according to its Lab numbers) but then I'm assuming you weren't going for accuracy. Your camera reproduces daylight scenes quite different from my camera edited or unedited.

Yes, I wasn't going for accuracy. I wanted to learn what would happen if one were to rely on "auto" mode while making simple captures of scenes similar to your lake and foliage but with a reference we are familiar with. Without the Macbeth chart, I would not know to what degree captures were effected but now I do know the trend.

The trend was; the camera changed white balance settings and exposure significantly with all the captures being good, especially for an amateur I think. Lightroom "auto" buttons showed good judgement for WB but trended to make the overall scene too light and sometimes too saturated in instances. I'm still curious to learn what the software finds in the scene to make that adjustment, however those adjustments might produce a very good prints from consumer grade printers without ICC color management.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 04, 2018, 06:54:25 pm
Yes, I wasn't going for accuracy.
I'd like to see what you'd get trying, because at least the one 'invisible' hue (Magenta patch) is pretty darn close to what it should be IF you adjust brightness of the image. We could analyze the other 23 patches of course. It would probably poke more holes in Tim's comments about your captures; at least the one I examined and he of course didn't!
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 04, 2018, 07:24:54 pm
@ TonyW #44
Can it be that simple!
One click on 'Auto Levels' under the Exposure tab in RawTherapee, and the image is basically OK. The sky is pale, which is probably correct, but pale BLUE! And its saturation increases after I discovered  'Raw White Points' under the Raw tab and set it from the default 1.0 to the minimum value which is 0.1. Now I can play a little with contrast without desaturating the sky too much. (If then I re-set AutoLevels, the image becomes VERY dark, so that's obviously why the default is there).

The AutoLevels set Black to +1956, Contrast to +25 and Saturation to +30. No change in Lightness. Normally, I don't like 'Auto'. But the good thing with this one is that I can see what it does and modify if needed. I forgot to note the change in Exposure compensation.

So it looks like my camera and monitor profiles are OK - relief!

Many thanks to all who chimed in!
---
Uff not quite that simple... But this is about RT

Now after I saved the Raw White Point of 0.1 as part of a Processing Profile preset, then choose that, then AutoLevels, it sets Exposure Compensation to +5.34, Black to 1954, Contrast to +24. No change in Saturation.
If I choose the preset with Raw White Point 1.0, then click AutoLevels,  it sets Exposure Compensation to 2.27, Black to 2045, Contrast to 27.  No change in Saturation.

Why does RT change its mind that way?
The 0.1 profile was initially (by mistake) saved under the image file name and re-named in the Mac Finder. Likewise, the 1.0 profile was re-named to include the 1.0 in the name. This could not possibly have any influence on the processing parameters??
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 04, 2018, 07:55:29 pm
@ TonyW #44Can it be that simple!

It can also be as simple as post #19. Care to post your results when you're happy with them?

Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 04, 2018, 08:01:25 pm
I'd like to see what you'd get trying,

The next time I experiment, which should be very soon, I will include something to reflect an actual specular highlight and a shaded black velvet swatch to reference an actual white point and black point along with the Macbeth.
Title: Re: The sky is blue - or should be...
Post by: Czornyj on May 05, 2018, 09:01:58 am
I agree that photography can be an interpretive artform but I've gotten pretty darn close to reproducing daylight scenes in my locale as it appears to me despite the limitations of my old DSLR. In addition I've found photos posted of daylight scenes over in Photo.net's No Words forum from non-professional photographers come really close, better than my camera.

I have a background in photo realistic painting and have extended experience mixing colors made from various pigments and dyes. I know what light does to natural memory colors. I do believe the limitation for not being able to get very close to representing any natural color captured with a digital camera shooting Raw is mainly the photographer's fault.

I have background in oil painting, and never found paintigs nor photography realistic.
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 05, 2018, 03:52:58 pm
@Stephen Ray #82

>It can also be as simple as post #19.

But #19 was simple and wrong - this is simple and right. As simple as that ;-)

>Care to post your results when you're happy with them?

Of course. I just was delayed by that RT problem.
After RT AutoLevels, I raised Contrast to 36, Saturation to 30. Nothing else.
Whole image and 2 crops - still undecided. The image idea was not the idyllic scene, but the shades of green and the "furry" look of the willow trees (the yellow ones).

Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 05, 2018, 04:30:57 pm
Some after-thoughts
and an attempt to make me a rhyme.

So this whole thing was not about profiles nor color memory, it was about saturation.
How come that the sky was desaturated to that degree, since all channels were far from clipping?
The image was underexposed, which made gross lightening in the raw converter necessary. This is done in Lab space, which desaturates colors as lightness increases.
Correct?
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 05, 2018, 04:40:20 pm
So this whole thing was not about profiles nor color memory, it was about saturation.
Pretty much yes, not that some profiles might produce a more desirable rendering along with differing settings and possibly a different converter could have provided a more pleasing rendering. But no, this idea of memory color being accurate or matching the scene is pretty bogus at least in terms of a match. We saw this below with the two green plant examples (#75) where we are supposed to believe (and we should not) that when sitting in front of a computer display with a gamut and dynamic range that alone is vastly different from what we can see, this user actually accurately recalls what he saw minutes, hours or days prior and is making a match. The key word may be memory, what one thinks he recalls but that in no way means what is produced was a match. Plus one is output referred!*
* http://www.color.org/ICC_white_paper_20_Digital_photography_color_management_basics.pdf
Quote
How come that the sky was desaturated to that degree, since all channels were far from clipping?
Exposure such there are one or more channels clipping and saturation are not mutually exclusive per se.
Quote
The image was underexposed, which made gross lightening in the raw converter necessary. This is done in Lab space, which desaturates colors as lightness increases.
What was 'done' in Lab space and why is that necessarily pertinent?
Rendering the image is an important part of photography and has little to do with color accuracy and matching:
http://www.lumita.com/site_media/work/whitepapers/files/pscs3_rendering_image.pdf (http://www.lumita.com/site_media/work/whitepapers/files/pscs3_rendering_image.pdf)
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 05, 2018, 07:21:52 pm
@Stephen Ray #82

>It can also be as simple as post #19.

But #19 was simple and wrong - this is simple and right. As simple as that ;-)

>Care to post your results when you're happy with them?

Of course. I just was delayed by that RT problem.
After RT AutoLevels, I raised Contrast to 36, Saturation to 30. Nothing else.
Whole image and 2 crops - still undecided. The image idea was not the idyllic scene, but the shades of green and the "furry" look of the willow trees (the yellow ones).

Please keep trying Hening. Your attempts are still much too dark. If you were familiar with Levels you could easily see so. You could also use the control to lighten the scene to something more normal and then you would be surprised as to how close it appears to my original post #19. When I do the same to your attempt(s), I am not surprised by how grossly cyan your new sky becomes because you've tried to add so much color that was never there. It's very easy for me to determine the original blue sky was only very slightly blue, in fact almost neutral.

Good luck in your processing. It takes time.

EDITED TO MENTION:  To be sure, this is your art and your interpretation. Forward ahead!
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 07, 2018, 02:54:07 am
Some after-thoughts
and an attempt to make me a rhyme.

So this whole thing was not about profiles nor color memory, it was about saturation.
How come that the sky was desaturated to that degree, since all channels were far from clipping?
The image was underexposed, which made gross lightening in the raw converter necessary. This is done in Lab space, which desaturates colors as lightness increases.
Correct?

There is a lot more wrong with your image than what you've outlined. The entire image is not white balanced for the time of day it was shot which appears to be around mid day. All three attempts of what you posted still have a funky cyan/thalo green cast. I guess my point about magenta neutralizing such types of casts wasn't working for you.

This is my attempt editing the first of the three you posted in ACR 6.7. I had to apply a luminance bump curve so the tops of the foliage appear to be lit directly by the sun. As it is it looks overcast with the funky white balance. Severe HSL adjusts did the rest with a magenta tint slider of +30.

This whole thread has clearly illustrated Raw Therapee is not an app I want to edit my Raw files in if Hening is having this much trouble white balancing it. Sorry, I had to say it but I got more done working on the jpg in ACR than the time it takes to read this entire thread.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 07, 2018, 10:16:00 am
There is a lot more wrong with your image than what you've outlined.
Not as there is as much wrong with your text here. Hening's image is under exposed; that's it. Had you even examined the raw Histogram (knew how?), you'd see that. Accept it, that's another doubtful error of yours.

Hopefully Hening and other's can see such facts and continue to ignore your misinformed posts here. You've gone on record in just this series of posts, multiple times ignoring the facts provided to you, other's are allowed the same tactic in ignoring you.
There is a lot more wrong with your text than what you've outlined. But other's have done a good job outlining it for your readers even if you ignore the corrections.
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 07, 2018, 02:17:16 pm
@ Andrew #87
> What was 'done' in Lab space and why is that necessarily pertinent?

Well I think the lightening. It is my understanding (and experience), that increasing lightness in Lab will desaturate colors. If this is true, it would be pertinent to the case, no?
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 07, 2018, 02:18:02 pm
@Tim #89
Sorry Tim, but I find your edition has too much magenta in the sky and too much yellow in the foliage. Yes my tone curve needs more work, but my focus so far were WB/colors, and I find them in the ball park now.

You are right that the image is not white balanced to the time of the day, which is indeed around 13h. So the true WB may have been closer to 6000K than 5000. However, if I move the WB in that direction in the raw converter, the image becomes more yellow, which did not comply with my then fresh memory.

Whatever failures my edit still may have, they are most likely not the fault of RawTherapee. RT lets you manipulate more parameters than  I understand (e.g. wavelets). WRT WB, it allows an adjustment not only of the blue-yellow and green-magenta, but also the red-blue balance (not that it helped me in this case though).
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 07, 2018, 02:19:52 pm
@ Andrew #87
> What was 'done' in Lab space and why is that necessarily pertinent?

Well I think the lightening. It is my understanding (and experience), that increasing lightness in Lab will desaturate colors. If this is true, it would be pertinent to the case, no?
In true Lab processing, it shouldn't. Lightness is a perceptually scaled component of color, the axis seen in Lab (Lstar) from light to dark. It IS the L in HSL. Such an edit shouldn’t affect color (aStar and bStar) but the appearance 'may' appear as less saturation.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 07, 2018, 02:23:40 pm
You are right that the image is not white balanced to the time of the day, which is indeed around 13h. So the true WB may have been closer to 6000K than 5000. However, if I move the WB in that direction in the raw converter, the image becomes more yellow, which did not comply with my then fresh memory.
Don't get caught up in this rubbish idea that the numbers are meaningful, the color appearance, output referred, as you view it on (hopefully) a calibrated and profile display does. Tim hasn't any idea about this; the WB setting at the scene wasn't measured with the correct device so it's unknown aside from a large guess the camera is providing, the numbers define a very large range of possible colors, even if you did measure the scene with a Spectroradiometer, and even IF the converter's idea of a CCT value was in sync, it's quite possible you, as the image creator wouldn't like it as much as something you pick moving about the sliders. This has absolutely nothing to do with 'accurate' color (colorimetric matching color), and much more to do with rendering the image as you the photographer desires. Tim's numbers/WB rabbit hole is just that, a big hole you don't need to join him inside of. Again to dispose this hole:
http://www.lumita.com/site_media/work/whitepapers/files/pscs3_rendering_image.pdf (http://www.lumita.com/site_media/work/whitepapers/files/pscs3_rendering_image.pdf)
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 07, 2018, 02:44:13 pm
Hening, this is the kinds of tools necessary to measure the color of light correctly, Tim has none. The camera doesn't provide anything like this data!
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 07, 2018, 03:57:29 pm
What strikes me is that you have to choose an illuminant (D50) on beforehand - wasn't this what was to be measured? And even if I had that spectrophotometer and would carry it in the field - how would I translate its reading (the graph) to WB settings in the raw converter?
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 07, 2018, 04:02:28 pm
What strikes me is that you have to choose an illuminant (D50) on beforehand - wasn't this what was to be measured? And even if I had that spectrophotometer and would carry it in the field - how would I translate its reading (the graph) to WB settings in the raw converter?
D50 is a specific color, any CCT value is a range. D50 was developed by averaging hundreds of measurements around the world, using differing spectroradiometers too! You don't have to choose a Standard Illuminant (of which D50, D65 are), nor do you have to choose any CCT Kelvin value per se at any specific time other than in the raw converter when you wish to adjust the WB to appear as you desire. So you would have zero need to measure anything in the field unless you wanted actual colorimetric data as I did show last post, for your own information. But above and beyond the processing of the raw data, the numbers are not needed or useful.

You can take the same raw, with the same CCT metadata embedded into two different raw processors and get two different WB appearances! What looks 'right' to you as the image creator? That's the right number. The stuff Tim's talking about in terms of numbers is absolutely off topic and not pertinent (and rubbish) to how you process your images. Wrong data from the wrong measurement device (if I can be so kind), and that wrong data does nothing useful you can't control by altering the sliders or controls in your raw processor until you get to the desired color appearance.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 07, 2018, 04:09:32 pm
@Tim #89
Sorry Tim, but I find your edition has too much magenta in the sky and too much yellow in the foliage.
Proof of wrong concept about editing on CCT WB numbers alone while ignoring how an image appears. Just ignore this silly concept.
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 07, 2018, 04:22:13 pm
@Andrew
> In true Lab processing, it shouldn't.
Then *why* is the sky desaturated in an underexposed image? (Still trying to make me a rhyme.)
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 07, 2018, 04:31:48 pm
@Andrew
> In true Lab processing, it shouldn't.
Then *why* is the sky desaturated in an underexposed image? (Still trying to make me a rhyme.)
It's one, 'incorrect' rendering interpretation, nothing more. You've seen the same raw file rendered differently with more saturation right?
Oh, and to dismiss Tim's idea and backup my last post about differing raw converters both interpreting the WB differently and producing the rendering differently, here is one .DNG in two different raw processors with defaults: LR and Iridient Developer. Note what the later states for WB!


(http://digitaldog.net/files/RawWB_Differences.jpg)
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 07, 2018, 11:07:47 pm
@Tim #89
Sorry Tim, but I find your edition has too much magenta in the sky and too much yellow in the foliage. Yes my tone curve needs more work, but my focus so far were WB/colors, and I find them in the ball park now.

You are right that the image is not white balanced to the time of the day, which is indeed around 13h. So the true WB may have been closer to 6000K than 5000. However, if I move the WB in that direction in the raw converter, the image becomes more yellow, which did not comply with my then fresh memory.

Whatever failures my edit still may have, they are most likely not the fault of RawTherapee. RT lets you manipulate more parameters than  I understand (e.g. wavelets). WRT WB, it allows an adjustment not only of the blue-yellow and green-magenta, but also the red-blue balance (not that it helped me in this case though).

If it isn't Raw Therapee's fault then why doesn't that image look like it was shot in daylight even if the blue sky looks right? I've edited 100's of daylight landscape, city scape and my local park and never would I settle for the results demonstrated in this thread including my own effort.

I mean you can speculate all you want but there's more to a landscape than just getting a "correct" looking blue sky. Can you post a different daylight landscape image processed in Raw Therapee that does look right including the blue sky? I can't believe we've all spent so much time and effort just to get the blue sky to look right while the rest of the image looks so wrong!

I still don't know what can be learned about processing color images from this thread.
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 07, 2018, 11:33:27 pm
About that different daylight landscape processed in Raw Therapee, make sure it has greens, browns, blues, yellows or any color variety but don't post a picture of sand dunes which is too simple of an image with very few memory colors.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 08, 2018, 08:58:18 am
About that different daylight landscape processed in Raw Therapee, make sure it has greens, browns, blues, yellows or any color variety but don't post a picture of sand dunes which is too simple of an image with very few memory colors.
Too simplistic for simpletons is more like it;snapshot you provided below that falls into simplistic camp!
Quote
I've edited 100's of daylight landscape, city scape and my local park and never would I settle for the results demonstrated in this thread including my own effort.
That many snapshots?  :D 
Tim is of course, wrong again:

(http://digitaldog.net/files/LRvsRDWB.jpg)
(http://digitaldog.net/files/TImISWrongAgain.jpg)
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 10, 2018, 03:42:35 pm
@ Tim #101
Hi Tim,
> If it isn't Raw Therapee's fault then why doesn't that image look like it was shot in daylight even if the blue sky looks right?

Well it looks OK to me, may need more work on the TRC, but I find colors in the ball park.

> Can you post a different daylight landscape image processed in Raw Therapee that does look right including the blue sky?

I'll try.
Here is another daylight landscape, shot on May 10th, 2016, at 17:21 h. Opened in Iridient, in RT, and in RT with contrast +20 to match Iridient. No other edits. Same profile, my custom created in DCamProf (Combo LUT). I have to admit that I like the sky in Iridient a little better. 
Difference is visible even in the jpegs. (This is not my final edit!)

> I still don't know what can be learned about processing color images from this thread.

Well what I learned is that RT's AutoLevels saved me an underexposed image, which I was unable to do manually. And that the problem was this underexposure, and the saturation, not the profiles, color memory or white balance.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 10, 2018, 03:48:36 pm
> I still don't know what can be learned about processing color images from this thread.

Well what I learned is that RT's AutoLevels saved me an underexposed image, which I was unable to do manually. And that the problem was this underexposure, and the saturation, not the profiles, color memory or white balance.
He doesn't know what can be learned; true and by brute force of his own desire not to learn.
Inidient Developer is a very good package.
Yes, part of your problem was under exposure and yes, you can 'fix' that if you understand the tools available to do so and the net result is just a bit more unnecessary noise in the shadows due to the under exposure.
Title: Re: The sky is blue - or should be...
Post by: BobDavid on May 10, 2018, 07:32:17 pm
The sky is often tricky to capture: cameras, lenses, sensors, RAW processors, human sensation and perception, atmospheric conditions, UV index, etc. make for lots of variables. And, we all have slightly different expectations of how the sky looks.

The green or magenta signatures that often shows up in digital photos are problematic; human vision is different from machine vision.
We've learned to expect the sky to be blue (on a clear day, depending on time of year and time of day, it generally falls within a dominate range of cyan) and so that's how we expect to see it. What's particularly interesting is that color perception is rather plastic. The brain white balances differently from how a camera works.

Another consideration is that the sky looks and always will look different on a screen than it will in a print.

So my advice, is to practice. There are lots of ways to alter the color of the sky. One technique is to add a layer, fill it with an appropriate hue, and then lower the layer opacity level to taste. Mask out the non sky areas to avoid contamination.

It's also fairly simple to make a composite by taking the sky from another picture. It's a good idea to build a stock library of skies taken with the same camera at a range of ISOs (to match noise).

Walk into a museum and see how painters render the sky. There's a lot of variation.
Title: Re: The sky is blue - or should be...
Post by: nirpat89 on May 10, 2018, 07:48:51 pm
The lesson is look at the histogram in the back of your camera before taking it to the RaeTherapy or whatever post-processing tool is to be used.  So you can immediately take another shot or two to correct the exposure.  And before starting to think about color management issues, make sure the histogram looks proper. 
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 10, 2018, 07:57:49 pm
@nirpat89
There was a strong wind, I had to use a short shutter speed, and was reluctant to open the aperture wider than f/8. I forgot to raise ISO - and I also forgot that it wouldn't have helped, as Andrew has pointed out in this thread. The value of the in-camera histo is limited as long as it is only based on the in-camera jpeg, not on the raw.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 10, 2018, 08:07:39 pm
The lesson is look at the histogram in the back of your camera before taking it to the RaeTherapy or whatever post-processing tool is to be used. 
When shooting a JPEG yes. When shooting raw, no. Not unless you've got a raw Histogram on the back of that camera.
Title: Re: The sky is blue - or should be...
Post by: nirpat89 on May 10, 2018, 08:16:44 pm
@nirpat89
There was a strong wind, I had to use a short shutter speed, and was reluctant to open the aperture wider than f/8. I forgot to raise ISO - and I also forgot that it wouldn't have helped, as Andrew has pointed out in this thread. The value of the in-camera histo is limited as long as it is only based on the in-camera jpeg, not on the raw.

Are you using manual mode?  ISO would have helped only in that case.  Yes, in-camera is a jpeg, but difference between an uncompressed raw or tiff file and a jpeg as far as histogram is concerned is not so great is to grossly misconstrue the exposure.  I bet the day was hazy, foggy or smoggy to start with as the dynamic range of the scene is quite narrow, not something you will get on a typical clear, sunny day with plenty of shadows - not in my experience.  Perhaps a polarizing or UV haze filter might have helped.

P.S. I would say the shot was not actually "under-exposed" in the classical sense as the shadows on the left were still not clipped.  Typically folks would add exposure in a scene like this to move the right side of the histogram all the way to the edge (exposing to the right or ETTR) which would help minimizing the noise in the shadows as Andy mentioned.
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 11, 2018, 03:45:07 am
@ Tim #101
Hi Tim,
> If it isn't Raw Therapee's fault then why doesn't that image look like it was shot in daylight even if the blue sky looks right?

Well it looks OK to me, may need more work on the TRC, but I find colors in the ball park.

> Can you post a different daylight landscape image processed in Raw Therapee that does look right including the blue sky?

I'll try.
Here is another daylight landscape, shot on May 10th, 2016, at 17:21 h. Opened in Iridient, in RT, and in RT with contrast +20 to match Iridient. No other edits. Same profile, my custom created in DCamProf (Combo LUT). I have to admit that I like the sky in Iridient a little better. 
Difference is visible even in the jpegs. (This is not my final edit!)

> I still don't know what can be learned about processing color images from this thread.

Well what I learned is that RT's AutoLevels saved me an underexposed image, which I was unable to do manually. And that the problem was this underexposure, and the saturation, not the profiles, color memory or white balance.

Hening, is there a reason your shots of a mid day scene look so dark? What happens when you brighten the image to look as bright as a noon day should?

I just shot the image below yesterday of my local park. Just another color perception test shot to check for yellows in greens, magenta in blue sky and neutral look of tree trunks. It's pretty darn close.

What's up with your dark daylight shots?
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 11, 2018, 12:43:25 pm
SNIP<The camera profile is created with DCamProf>SNIP

This is where I stopped reading the OP's very first post. Honestly. As I said in my first post #19, "Had the photographer not interfered."
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 11, 2018, 12:45:44 pm
Interfered how, with his own profile compared to what?
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 11, 2018, 01:10:40 pm
Interfered how, with his own profile compared to what?

Yes, with his own profile, which I believe is inferior to something more normal to what the camera factory settings should provide. 
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 11, 2018, 01:25:29 pm
Just another image for comparison against the OP's original post image.

Late August, 1:PM, viewing south-west, Canon Rebel using kit-lens, exposure set by camera, Lightroom WB 5500k/+10M, no other LR changes.

The scene is similar with blue sky areas, sunlit treetops, and green lawn tones (center distance.)
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 11, 2018, 01:36:48 pm
I just shot the image below yesterday of my local park. Just another color perception test shot to check for yellows in greens, magenta in blue sky and neutral look of tree trunks. It's pretty darn close.

Just another image for comparison against your posted image, Tim.

May 22, 2016, 1:PM, viewing West, Canon Rebel using kit-lens, image straight out of the camera, no PS or LR adjustments.
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 11, 2018, 01:40:10 pm
Yes, with his own profile, which I believe is inferior to something more normal to what the camera factory settings should provide.
What camera factory setting? It's raw.
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 11, 2018, 03:13:44 pm
What camera factory setting? It's raw.

Does not the OP's camera profile options show in any of his raw processors?
Title: Re: The sky is blue - or should be...
Post by: digitaldog on May 11, 2018, 03:15:48 pm
Does not the OP's camera profile options show in any of his raw processors?
Which one? In which product? And even if they did, the same profile would very likely produce differing results in two different converters. Just like CCT Kelvin numbers already provided.
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 11, 2018, 04:32:53 pm
@ Stephen Ray
Yes my raw converters give me a choice of camera profiles I have stored, and they also have a default for each camera.
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 11, 2018, 04:35:16 pm
@ Tim

> If it isn't Raw Therapee's fault then why doesn't that image look like it was shot in daylight even if the blue sky looks right?

> Hening, is there a reason your shots of a mid day scene look so dark? What happens when you brighten the image to look as bright as a noon day should?

Here is a new attempt in RT. Black WP 0.1 [--edit: *Raw* WP 0.1, of course!], Auto Levels, then Contrast raised from 25 to 45, Saturation from 0 to 10. Does this look more like daylight? If not, I don't know what to do. I'm afraid the contrast is  a bit high already. Could it be that noon daylight in Texas looks different from noon daylight in NE Germany?
It might also be that a cloud was just about moving into the sun. The sky was blue, but there were shifting clouds, as you can see on the green foreground, which lies all in shadow except a little snippet at left.
I share your concept that a landscape image should render the light of the scene. In this particular image however my focus is not on the overall mood, but on the colors of the foliage as a structure or pattern.

WRT to my second image, 346, this is not noon, but 17:21. (That is "real" time, not Daylight Saving Time). And most of the image field lies in the shadow. 1/2 of it is reflection on the water, which darkens the image even further. I'll try to show 2 attempts on this one later.
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 11, 2018, 05:24:40 pm
@ Stephen Ray
Yes my raw converters give me a choice of camera profiles I have stored, and they also have a default for each camera.

If you were to use any default camera profiles from any of your raw processors and possibly use some "auto" settings for exposure, do you suppose your images could be improved as far as appearing more natural? Is the exercise not an easy experiment?
Title: Re: The sky is blue - or should be...
Post by: Peter_DL on May 11, 2018, 05:41:43 pm
Here is a new attempt in RT.
... Does this look more like daylight?

Leider nein.

In ACR, the Split Toning function can help to make the greens warmer without eliminating the blue in the sky
- as opposed to the Temperature slider in this case.

Peter
--


Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 11, 2018, 10:31:26 pm

Does this look more like daylight?

If not, I don't know what to do. I'm afraid the contrast is  a bit high already. Could it be that noon daylight in Texas looks different from noon daylight in NE Germany?

It might also be that a cloud was just about moving into the sun. The sky was blue, but there were shifting clouds, as you can see on the green foreground, which lies all in shadow except a little snippet at left.
I share your concept that a landscape image should render the light of the scene. In this particular image however my focus is not on the overall mood, but on the colors of the foliage as a structure or pattern.

WRT to my second image, 346, this is not noon, but 17:21. (That is "real" time, not Daylight Saving Time). And most of the image field lies in the shadow. 1/2 of it is reflection on the water, which darkens the image even further. I'll try to show 2 attempts on this one later.

All of your posted images so far look like I'm viewing the scene through bluish green dark sunglasses.

Here's another option. Load those Raw images in Lightroom or ACR and see if you get closer to not having them look so dark and blue green.

Even Stephen's posted images look reasonably close to what a daylight scene should look. Since he didn't do any edits I'm assuming it's just for reference of what another Raw converter can deliver which is a huge improvement over your results.

Your images remind me of my first Raw scans of prints and negatives off my Agfa Arcus flatbed 20 years ago before I knew about ICC profiles. I'ld get those dark dull bluish scans and try to edit in Photoshop and never make any headway. Not even the Hue/Sat tool made a dent. Curves didn't work either.

Assigned the canned Agfa Arcus scanner profile and got a huge improvement.
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 12, 2018, 11:23:02 am
@ Stephen Ray # 122

RawTherapee has a number of processing profiles, I tried some and have selected 2 that I think come closest. (1+2). Then I have paired them with my own camera profile (3+4), then the other way round, RT camera profile with my processing like in post #121 (5).
My view: Punchy 2 is too punchy, the snippet of sun-lit green at left is too shiny. Punchy 1 is quite natural, but maybe a little too yellow. I find my own processing has the best separation in the green foliage. [Yes they *are* greens, not yellows, fellows ;-) ] - The 2 camera profiles are almost indistinguishable, the processing makes the difference. - I find all of the skies in the ball park.
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 12, 2018, 11:24:29 am
and here #5 attachment:
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 12, 2018, 03:10:59 pm
Those are pretty good improvements but I think this is not an ideal image to test out color consistency performance of DcamProfiles and Raw Therapee.

The fact that you've had to put this much work into just getting it sort of correct looking isn't an indication that'll it'll be easier on other daylight images. This is a simple daylight scene and it's just not working.

Like I asked previously and you didn't do what I asked, I'll ask again...

PLEASE post another midday daylight shot that has a wide range of memory colors like browns, greens, oranges, blues and a neutral target like a CC chart so you know for sure you will get consistent results using DCamProfiles and Raw Therapee.

As it is I'm not convinced this is an ideal color rendering workflow. It looks like too much work and I've processed over 3000 Raw images depicting a wide range of some very HELLISHLY challenging mixed WB and dynamic range scenes especially those in dark heavily wooded and shaded areas with blue sky and bright sunlight back lighting. I have more issues scaling shadows to black point and making sure they don't look too blue than I have working on bright daylight scenes such as yours.

See the before and after Raw edits of some typically challenging scenes I deal with. I got it to look exactly as it appears. To get the greens to look correct I had to apply a dual illuminant D65 Adobe DNG profile created using only one D65 CCchart target image. It puts the right level of cyan in green leaves instead of the cooked yellowish green that a regular single illuminant D65 profile renders. But I still had to use HSL edits to bring out clarity in the green leaves and foreground tree limbs.
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 12, 2018, 03:52:31 pm
@ Peter_DL #123
Peter, these bushes and trees were green, and I see no reason to turn them yellow.

@ Tim
I don't have ACR nor Lightroom.
Here is another attempt at 346, a little more punchy, maybe not final, but in the ballpark (in my view), the mirrored image may need a separate mask, but that is more than what I can do at the moment.
--edit: no forget about this, I'll try to remove the attachment if that is possible

> Those are pretty good improvements

Hm - my favorite is still my edit from post 121, and I find it almost indistinguishable from #5 in post 126 - the only difference being the camera profile.

Here (275) is another midday daylight shot (without a CC chart though). It was not tricky to process color-wise - processed in Iridient, TRC in PhotoLine in HSV_V. Parts of the sky are either blown or that are clouds, more likely.

Do you think this is more natural than the willows (3216)? Maybe the lighting in that scene is not quite as straightforward as it appears, due to the moving clouds which put the image partly in the shadow, see the green foreground and the right hand side part of the white bushes. It may look like the shadow from that sky was just about reaching the 'gallery' in the middle ground.
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 12, 2018, 05:02:53 pm
#275 looks a lot more normal and correct for such a green leaf shaded scene, so I'm going to say the original OP image was just one of those problem images.

I still think your profiles and WB adjusts don't do enough of a job of removing the colored (bluish green, or yellowish) stained filter that full spectrum lighting removes. And that may be due to the limitations of a profile to correct for individually colored elements that WB edits can't fix.

The image below is a test image sample I came up with years ago that illustrates the limits of WB adjusts that is suppose to remove the overall colored stain appearance that's noticeable in image #275.

The one on the left is the unedited Raw shot under daylight balanced flotube showing this dull greenish yellow stain over the entire image. The one on the right is hitting Auto WB in ACR which didn't change Color Temp slider but did force +20 toward magenta. It still didn't get rid of the greenish yellow stain throughout all the other colors. I had to use a real dual illuminant DNG Profile which still wasn't enough to make the cracker look more toasted orange instead of pale yellow orange.

The one on the right looks fresher and more vibrant which is what full spectrum light does to scenes like this. There's no dead/cooked greens, there's no orangy tomato and a lot of that came from HSL adjusts in ACR.

I don't get that daylight full spectrum feel from your images, but the last one looks like it would look with all the green leafy shade but it's more than what I see out in nature.
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 12, 2018, 05:11:08 pm
How about posting another daylight scene that's not affected by green leafy shade and still shows a full blue sky? I can't believe you don't have other daylight scenes with more memory colors. Is it sunny in your area?
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 12, 2018, 05:23:28 pm
A correction: I shot the cracker, lettuce, tomato test image under household 2800K soft white tungsten light bulb. That's why my incamera WB shows a color temp of 3100/+17 in ACR as default WB. It was several years ago when I shot that test image so my memory is a bit off.
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 12, 2018, 11:34:42 pm
Interesting how green trees might be more yellow than believed at this time of year. Curiously similar in color as to what the camera raw auto button performed upon the OP's first post when I experimented in post #19.

Pollen Tree Explosion at YouTube (https://www.youtube.com/watch?v=zxgRNK2EysI)
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 13, 2018, 12:40:05 am
I eventually processed the OP's RAW using RawTherapee. RT set WB to 4600 with some magenta tint. I pressed the auto button for levels. I added some contrast and saturation. I zoomed to 100% and noticed horrendous lens CA and overall lens inferiority. I explored RT a short while and then decided to export a high rez 8bit tiff to Photoshop because I know the key commands there. After some zooming in and out from many areas of the scene, I further noticed the color contamination by lens CA in areas of high detail frequency was worse than I thought. I decided not to spend any more effort because my processing was already bright, colorful, neutral (as I cared to make it), and VERY much like my effort in my post #19 from just running the auto buttons in camera raw on the OP's first JPG.

Many earlier posts have suggestions and remedies and I agree many or all to be valid and helpful to the OP for his future efforts.
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 13, 2018, 02:19:11 pm
@ Tim
I don't have so many (good) shots with large amounts of open sky as you might exspect, but I found 2.

Camera Profile is my Combo_LUT.ICC  for the a7r2
1980 RT AutoLevels, then Contrast 50 (1 focus slice)
2365 RT AutoLevels, then Lightness +10, Contrast 30 (1 focus slice)

In the process of browsing, I also found some images where I am not happy with the sky at all. Maybe I show these later, and my attempt to fix it.
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 13, 2018, 02:27:39 pm
@ Stephen Ray #133:

The lens was a Zuiko 3.5/135. Concerning the CA: Did you turn on RT's amazing automatic CA correction (Raw tab)? The 2 screen shots show an area at utmost left at 400%, with and without CA correction.
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 13, 2018, 03:51:33 pm
The CA is a minor issue. It's not going to influence the overall color. I have far worse CA from my kit lens which I used with all my posted edited Raws.

#2365 is the best at rendering a daylight scene. All the colors look as it should including the blue sky. I'm not sure why the thin tree branch highlights in #1980 are a greenish yellow. It's a winter scene going by the dead grass in the far right corner so it can't be pollen.

I examined a few daylight lit, ISO 100 sample incamera jpegs with blue sky and green trees and a stone masonry building from the Sony Ar7ii over at PhotographyBlog.com and can see it has no problems rendering color correctly no matter where the sun is located in the sky.

So we have one image (#2365) that looks right using your DcamProfile and whatever converter of choice. Not a workflow I'ld adopt for myself but if it works for you, Hening, stick with it.

I don't know what else to add so I'm going to move on.
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 13, 2018, 04:02:57 pm
Fine that this image seems right.
> I'm not sure why the thin tree branch highlights in #1980 are a greenish yellow.
They have this color - it's a lichen, and the contrast between this yellow-green and the orange of the other willow is a main part of the image idea. :-)
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 13, 2018, 04:28:01 pm
The CA is a minor issue. It's not going to influence the overall color. I have far worse CA from my kit lens which I used with all my posted edited Raws.

It is affecting overall color in large areas. That's why I brought it up. It's that bad.
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 13, 2018, 04:34:54 pm
Fine that this image seems right.
> I'm not sure why the thin tree branch highlights in #1980 are a greenish yellow.
They have this color - it's a lichen, and the contrast between this yellow-green and the orange of the other willow is a main part of the image idea. :-)

So now you have two images that look correct. The greenish yellow I would not have taken to be lichen because it's on very thin branches and not on the rest of the tree. It looks like a highlight fluoresce effect.

Several years ago I encountered something similar what I had to define as a metameric issue photographing similar lichen on a large area of stone lit by a sunset I shot on print negative film and scanned. It was hell editing it in Photoshop to get it to look like it fit in the scene and not have it appear as a color anomaly or lab processing error. I gave up on it.
Title: Re: The sky is blue - or should be...
Post by: Tim Lookingbill on May 13, 2018, 04:38:02 pm
It is affecting overall color in large areas. That's why I brought it up. It's that bad.

Can you provide a screengrab where this CA is influencing the overall patina of the image? Like turn on/off CA correction and show the entire image's color change?
Title: Re: The sky is blue - or should be...
Post by: Stephen Ray on May 13, 2018, 05:00:48 pm
@ Stephen Ray #133:

The lens was a Zuiko 3.5/135. Concerning the CA: Did you turn on RT's amazing automatic CA correction (Raw tab)? The 2 screen shots show an area at utmost left at 400%, with and without CA correction.

Hening,

I have now tried RT auto CA correction. It helps but still not nearly satisfactory. Sorry, but a rather poor lens.

One might zoom into the attachment to better discern the color problems. (Grabbed from the center white flowers that should be more neutral without cyan artifacts as well as other colors.)
Title: Re: The sky is blue - or should be...
Post by: Hening Bettermann on May 13, 2018, 05:26:18 pm
> a rather poor lens

I know. I'll buy a Zeiss ZF2 2.0/135 - if you carry it for me ;-)