Pages: [1] 2 3 ... 8   Go Down

Author Topic: The sky is blue - or should be...  (Read 3426 times)

Hening Bettermann

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 892
    • landshape.net
The sky is blue - or should be...
« 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!


andrewrodney

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 13483
    • http://www.digitaldog.net/
Re: The sky is blue - or should be...
« Reply #1 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?
Logged
Andrew Rodney
Author “Color Management for Photographers"

DP

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 266
Re: The sky is blue - or should be...
« Reply #2 on: May 01, 2018, 04:12:31 PM »

Logged

Hening Bettermann

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 892
    • landshape.net
Re: The sky is blue - or should be...
« Reply #3 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

Doug Gray

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1237
Re: The sky is blue - or should be...
« Reply #4 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.
Logged

andrewrodney

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 13483
    • http://www.digitaldog.net/
Re: The sky is blue - or should be...
« Reply #5 on: May 01, 2018, 05:10:56 PM »

Check to make sure you aren't blowing out the Red/Green channels.
Not even close:
Logged
Andrew Rodney
Author “Color Management for Photographers"

DP

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 266
Re: The sky is blue - or should be...
« Reply #6 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)...
« Last Edit: May 01, 2018, 05:29:10 PM by DP »
Logged

Hening Bettermann

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 892
    • landshape.net
Re: The sky is blue - or should be...
« Reply #7 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??

Hening Bettermann

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 892
    • landshape.net
Re: The sky is blue - or should be...
« Reply #8 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.

DP

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 266
Re: The sky is blue - or should be...
« Reply #9 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 ...
Logged

andrewrodney

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 13483
    • http://www.digitaldog.net/
Re: The sky is blue - or should be...
« Reply #10 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.
Logged
Andrew Rodney
Author “Color Management for Photographers"

Hening Bettermann

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 892
    • landshape.net
Re: The sky is blue - or should be...
« Reply #11 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.

andrewrodney

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 13483
    • http://www.digitaldog.net/
Re: The sky is blue - or should be...
« Reply #12 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.
Logged
Andrew Rodney
Author “Color Management for Photographers"

DP

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 266
Re: The sky is blue - or should be...
« Reply #13 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
Logged

Tim Lookingbill

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 2374
Re: The sky is blue - or should be...
« Reply #14 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.

Logged

GWGill

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 452
  • Author of ArgyllCMS & ArgyllPRO ColorMeter
    • ArgyllCMS
Re: The sky is blue - or should be...
« Reply #15 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.)

Logged

andrewrodney

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 13483
    • http://www.digitaldog.net/
Re: The sky is blue - or should be...
« Reply #16 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.
Logged
Andrew Rodney
Author “Color Management for Photographers"

andrewrodney

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 13483
    • http://www.digitaldog.net/
Re: The sky is blue - or should be...
« Reply #17 on: May 02, 2018, 10:21:09 AM »

Magenta is the invisible hue ....
What, seriously?
Logged
Andrew Rodney
Author “Color Management for Photographers"

nirpat89

  • Full Member
  • ***
  • Offline Offline
  • Posts: 213
    • Photography by Niranjan Patel
Re: The sky is blue - or should be...
« Reply #18 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. 
« Last Edit: May 02, 2018, 11:46:59 AM by nirpat89 »
Logged

Stephen Ray

  • Full Member
  • ***
  • Offline Offline
  • Posts: 131
Re: The sky is blue - or should be...
« Reply #19 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.
Logged
Pages: [1] 2 3 ... 8   Go Up