Luminous Landscape Forum

Equipment & Techniques => Digital Cameras & Shooting Techniques => Topic started by: Lorenzo Pierucci on February 03, 2014, 02:34:33 am

Title: D800 clipping red channel ? Any possible solutions
Post by: Lorenzo Pierucci on February 03, 2014, 02:34:33 am
Hi everybody :)

I just come across on the net what seems to be the cause of my mayor "dislike" of my D800: skin rendering. Looks like the D800 have a certain tendency to blow up the red channel pretty quickly.

Many time when i shoot in studio i had perfectly expose ( exposimeter on my hand ) shoots, that produce burned skin tones. Also when i use it as day by day camera, shooting family and friends, the skin always turn in a yellow no detail tone, if i expose for the scene. There is no compare to Portra 400 or my Leaf DB.

So i start look around, and i saw some wedding photographer that achieve pretty nice skin tones with my same camera... But still some complain about this D800 blowing red channel.
I had a 5D II for years and i never had such problem, also seems that many big studio photographer are shooting with 5Ds ( as far i can see from back stage of Testino and Leibovitz ) when they don't use their Phaseone or Hassy backs.

I played with those files on C1, Craw and LR a lot, but there is not a fix workflow so far to me, as shoot portra with a 81A and expose for shadows :)

Anyone had similar experience or even better willing to share solutions?

Thanks to everyone that put time on this
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Bart_van_der_Wolf on February 03, 2014, 03:22:39 am
I just come across on the net what seems to be the cause of my mayor "dislike" of my D800: skin rendering. Looks like the D800 have a certain tendency to blow up the red channel pretty quickly.

Hi Lorenzo,

The question is, is the Red channel really blown in the Raw data, or does it get clipped after White-balancing? Most Raw converters only show a histogram of the RGB channels after demosaicing and White-balancing, so that won't help to find the cause. A Raw converter like RawTherapee (http://rawtherapee.com/blog/) does allow to switch the histogram to show Raw data, and it allows to remedy an issue like White-balance induced clipping. For Raw data analysis you can also use RawDigger (http://www.rawdigger.com/).

Once you know whether the Red channel is really clipped, you can take precautionary measures that reduce the Red channel exposure level (cooler lightsource, filter, reduce overall exposure). If the Red channel is not clipped, then it is probably an imbalance in the Red channel sensitivity, perhaps caused by IR. Human skin diffusely reflects IR reasonably well, so the camera should filter it to avoid contamination.

Then it is also possible that it is just a matter of getting a better profile, something you can achieve relatively easy with Capture One Pro, because you can adjust an existing profile in the Color editor (which has some very useful skin correction capabilities) and save that as a new profile.

Cheers,
Bart
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: ErikKaffehr on February 03, 2014, 04:16:41 am
Could you post a raw file showing the problem?

Best regards
Erik


Hi everybody :)

I just come across on the net what seems to be the cause of my mayor "dislike" of my D800: skin rendering. Looks like the D800 have a certain tendency to blow up the red channel pretty quickly.

Many time when i shoot in studio i had perfectly expose ( exposimeter on my hand ) shoots, that produce burned skin tones. Also when i use it as day by day camera, shooting family and friends, the skin always turn in a yellow no detail tone, if i expose for the scene. There is no compare to Portra 400 or my Leaf DB.

So i start look around, and i saw some wedding photographer that achieve pretty nice skin tones with my same camera... But still some complain about this D800 blowing red channel.
I had a 5D II for years and i never had such problem, also seems that many big studio photographer are shooting with 5Ds ( as far i can see from back stage of Testino and Leibovitz ) when they don't use their Phaseone or Hassy backs.

I played with those files on C1, Craw and LR a lot, but there is not a fix workflow so far to me, as shoot portra with a 81A and expose for shadows :)

Anyone had similar experience or even better willing to share solutions?

Thanks to everyone that put time on this
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Justinr on February 03, 2014, 11:34:57 am
I find skin tones notoriously difficult with any digital camera and the paler the skin the worse it gets.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Ellis Vener on February 03, 2014, 12:10:53 pm
Up until the 5d mark III and 1D X I found the Canon DSLRs to have far worse problems with skin tones than Nikon's DSLRs and I've never seen the problem you are encountering with your D800.

First things first: what are you using as lighting?

Are the red channels blown on your camera's histogram ( see http://www.ppmag.com/web-exclusives/2007/12/what-is-a-histogram-and-how-do.html to explain why that might be) or in your raw processing software's histogram?

Are you sure you are not over-exposing? The "Expose To The Right" mantra can be overdone you know.

Have you tried creating a custom camera profile for Lightroom or ACR to use?

I'd really want to see some examples before thinking this is not really a Canon lover's FUD in the guise of a complaint.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: ErikKaffehr on February 03, 2014, 12:27:53 pm
Hi,

There were some discussion on one of the MF-threads recently. I would be much interested to see some raw images with problematic skin tones, to see what it is about.

Personally I shoot Sony and no skin. So I have no samples of my own.

Best regards
Erik


Up until the 5d mark III and 1D X I found the Canon DSLRs to have far worse problems with skin tones than Nikon's DSLRs and I've never seen the problem you are encountering with your D800.

First things first: what are you using as lighting?

Are the red channels blown on your camera's histogram ( see http://www.ppmag.com/web-exclusives/2007/12/what-is-a-histogram-and-how-do.html to explain why that might be) or in your raw processing software's histogram?

Are you sure you are not over-exposing? The "Expose To The Right" mantra can be overdone you know.

Have you tried creating a custom camera profile for Lightroom or ACR to use?

I'd really want to see some examples before thinking this is not really a Canon lover's FUD in the guise of a complaint.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: LKaven on February 03, 2014, 01:34:05 pm
I just come across on the net what seems to be the cause of my mayor "dislike" of my D800: skin rendering. Looks like the D800 have a certain tendency to blow up the red channel pretty quickly.

One important question is what capture parameters are you using.  (This aside from questions about light sources, and other important questions also worth asking.)

If you are using C1, then for best skin tone results, I'd recommend using the "neutral" profile, which is really the linear profile.  First of all, it gives you the unpolluted color as well as the unmodified linear data.

If you use one of the tone curves, you will risk bunching up colors and color transitions, especially in skin tones.  The "standard" profile is the worst offender.  The "portrait" profile was created to mitigate some of these issues, but it also has some problems.  Also, if you use the standard/portrait tone curves, you will lose about .5 to 1 stop in highlight headroom, due to the way the tone curve boosts the highlights.  Some of the overexposure you mention just might be the result of this artificial boosting.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Some Guy on February 03, 2014, 06:20:11 pm
Red is an easy one to blow out if you over expose it in the Nikon.  Would be nice to see a RAW image you have done to analyze it.

Personally, I process NEF files with Nikon's Capture NX2 since their own processing engine takes all the camera's settings and uses them along with the "Nikon Adobe RGB 4.0" color space.  I'm not fond of other RAW converter's since they do not read the camera's settings as well.  In the camera's menu, I have the Saturation down a notch from normal, and maybe -0.6 as my default exposure as well.  I know the Sharpness is up a lot over the default as Nikon is normally soft there over Canon, but don't recall the Contrast I am using.   Some of this was trial and error using the x-rite ColorChecker and just trying to get the thing's default settings to reproduce that chart without a lot of post processing work in various converters.  Put that red channel too far to the into right on the histogram and it is difficult to pull any detail out of it, hence my tendency to underexpose a bit.  I prefer to call it "Expose for the Red."  Bright red neon-like cloths can be very hard to deal with once over-exposed. I output as TIFF from Capture NX2 also.  Any other post-work gets whatever other program I use past that point.

Fwiw, I get really nice skin tones out of that camera over my older Canon 5DII which seemed to like yellow.  The two companies do seem to have a difference when it comes to skin tone color out of their cameras.  The dynamic range is quite high and you can hold back exposure a bit, just look around for reds in the scene and figure out how much to negative exposure to apply to the default.

SG
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Lorenzo Pierucci on February 04, 2014, 11:49:46 am
Hi everybody

First of all: i know that this seems a hell of troll post but is not ( that's what a troll will says anyways…. )

I really have this things buzzing me for a while. First was look like that the LCD of the D800 ( mine is one of the first one produced as i bought as soon was come out ) had some color problems, and many seems agree of the yellowish colorcast. Then also when i bring images on the my desktop them looks not correct to me.

My issues is that when shooting outside, normally exposed scene turn to have skin tones usually burned, in order to avoid it, i got to underexpose. If I'm shooting in a studio, skins looks yellowish and hilights area have less details. I might be wrong, and if so feel free to correct me.

Thanks to all the people that share some workflow, I'm tying now all those technique both in C1 and this new ( to me ) Rawtherapee. Im also attaching 2 RAW:

1- is a studio shoot: skin turn out so yellow to me, she had a nice pink russian skin.
https://www.dropbox.com/s/9kbmec1oyc7bf9p/DSC_9837.NEF

2- my "girls" picking up strawberry, i had to turn exposure down a notch to get the skin workable.
https://www.dropbox.com/s/gkk7j2vr3xhdojp/DSC_2102.NEF

What I'm doing wrong? what is the best "recipe" to get a constant output that will look like kodak portra simile?
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Vladimirovich on February 04, 2014, 12:24:25 pm
1- is a studio shoot: skin turn out so yellow to me, she had a nice pink russian skin.
https://www.dropbox.com/s/9kbmec1oyc7bf9p/DSC_9837.NEF

not sure where did you get that "pink russian skin" thing ? are you talking about a girl (not a woman) outside in -10C after running around for a while ?

looks normal to me for an adult trying to watch her weight and sitting inside

http://imageshack.com/a/img838/4672/fs24.jpg

(http://imageshack.com/a/img838/4672/fs24.jpg)
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Bart_van_der_Wolf on February 04, 2014, 01:04:02 pm
1- is a studio shoot: skin turn out so yellow to me, she had a nice pink russian skin.
https://www.dropbox.com/s/9kbmec1oyc7bf9p/DSC_9837.NEF

This image is exposed 1.14 stops below clipping of the Green CFA channels, and the Red CFA channel is 2 stops below clipping. So there are no exposure clipping issues to be expected. Skin color looks perfectly normal to me (no jaundice). Camera and lighting quality is fine, no extreme IR contribution beyond design specifications. So if you see a yellow skin, it must be created  after Raw conversion and applying a profile and color balance. Time to check your Raw converter settings and check display calibration.

Quote
2- my "girls" picking up strawberry, i had to turn exposure down a notch to get the skin workable.
https://www.dropbox.com/s/gkk7j2vr3xhdojp/DSC_2102.NEF

The Green CFA channels are 0.22 stops below clipping, so perfectly Exposed-To-The-Right (ETTR), and the Red and Blue CFA channels are below that, so not clipped either. Again, check the Raw converter settings and Display calibration.

Cheers,
Bart
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Lorenzo Pierucci on February 04, 2014, 01:16:47 pm
Thanks guys for the time put on this, and great that images looks good to you.

Ergo => i might facing some display problems….
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: ErikKaffehr on February 04, 2014, 01:23:38 pm
Hi,

Thanks for posting the images.

I am no expert on skin tones but both look good to me. I checked both for channel clipping using raw digger and they are OK. My conversions are also well within sRGB so I don't think you have a clipping issue.

Best regards
Erik

Ps. :-) I am not familiar with nice pink russian skin, unfortunately. :-)

Hi everybody

First of all: i know that this seems a hell of troll post but is not ( that's what a troll will says anyways…. )

I really have this things buzzing me for a while. First was look like that the LCD of the D800 ( mine is one of the first one produced as i bought as soon was come out ) had some color problems, and many seems agree of the yellowish colorcast. Then also when i bring images on the my desktop them looks not correct to me.

My issues is that when shooting outside, normally exposed scene turn to have skin tones usually burned, in order to avoid it, i got to underexpose. If I'm shooting in a studio, skins looks yellowish and hilights area have less details. I might be wrong, and if so feel free to correct me.

Thanks to all the people that share some workflow, I'm tying now all those technique both in C1 and this new ( to me ) Rawtherapee. Im also attaching 2 RAW:

1- is a studio shoot: skin turn out so yellow to me, she had a nice pink russian skin.
https://www.dropbox.com/s/9kbmec1oyc7bf9p/DSC_9837.NEF

2- my "girls" picking up strawberry, i had to turn exposure down a notch to get the skin workable.
https://www.dropbox.com/s/gkk7j2vr3xhdojp/DSC_2102.NEF

What I'm doing wrong? what is the best "recipe" to get a constant output that will look like kodak portra simile?

Title: Re: D800 clipping red channel ? Any possible solutions
Post by: digitaldog on February 04, 2014, 01:47:07 pm
Ergo => i might facing some display problems….

Perhaps. The image looks fine on this end and in Lightroom follows what I'd consider a good skin tone ratio*

At least with Adobe raw converters, you can get a decent idea of color clipping based on it's histogram (either Melissa RGB or ProPhoto, close enough). The NEF shows nothing close to color or tone clipping, the skin tone values look good as a default starting point.

*(http://digitaldog.net/files/LR_Skintone_Ratio.jpg)
Here's a video on correcting skin tones without having to resort to CMYK using Adobe raw converters:

Low Rez (YouTube)
http://www.youtube.com/watch?v=dWaFDKrNrwc

High Rez
http://digitaldog.net/files/SkinToneVideo.mov
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Some Guy on February 04, 2014, 01:51:02 pm
Couple of things in your NEF files.

One is that you are all over the place in your "Picture Control" settings.  The woman is set for "Monochrome" (??). The girls are set as "Landscape" (Which is far more vivid.).  Also, you might want to pull the red back to the left in the histogram of girls shot by setting using your camera's Active-D lighting set to "Low" in Capture NX2.  This is done using Capture NX2 which you should be using to see what you are doing as you are all over the place in settings.  None of the other RAW processors are going to see this, nor know how to deal with it.  There is a difference and why Nikon recommends their software for initial post work.  I would hope their engineers know a bit more than the other software converter makers, Adobe included.

For fun, I also opened the woman's image in Capture One 6 and it is really saturated on color (and heavy towards an orange) verses Capture NX2 which looks far more natural.  Not a pleasant way to go on initial processing.  Adobe's 8.3 RAW and DxO Optics Pro 9 aren't as heavy on color saturation as CO, but both are warmer and more saturated than Capture NX2 which seems very neutral and natural.  No doubt there could also be an issue with Apple's Colorsync too if you use a Mac which always seems to mess up something or some driver matter with each version.

Aside, I'll agree with the D800 camera's LCD not being all that pleasant to look at over the Canon's LCD screen.  In studio it looked awful on the LCD prior to the last firmware update.  The Canon looked far better side-by-side.  My D800 had a sickly cyan/green color under studio lights, but the images were always good in post.  It looks warmer since the firmware update.  But I don't rely on it for an accurate representation as it cannot do that.  It ain't an Eizo screen!

These were out of the D800E.  The girl's costume is a bright red Shantung satin fabric that has a faint texture. The texture is still there.  Just have to watch exposure and the Active-D lighting control (and utilization in Capture NX2) to keep it there.

http://24.media.tumblr.com/2c8ef2fcbbbd6f7408c296a6e21ee626/tumblr_mp6h4dmzjH1s9g2zzo2_1280.jpg (http://24.media.tumblr.com/2c8ef2fcbbbd6f7408c296a6e21ee626/tumblr_mp6h4dmzjH1s9g2zzo2_1280.jpg)

Her skin coloring, although powdered by a MU person:

http://24.media.tumblr.com/2b3df062647757df7f0ca003f9d11adb/tumblr_mp6gtjvk441s9g2zzo2_1280.jpg (http://24.media.tumblr.com/2b3df062647757df7f0ca003f9d11adb/tumblr_mp6gtjvk441s9g2zzo2_1280.jpg)

Try and standardize your shooting control (maybe "Normal"), check your camera's exposure to see if it is leaning towards overexposure (All my Nikon's do for some reason so I set a minus value into them.), and use a decent converter that shows you what the camera was set on and doing (i.e. Capture NX2).  Capture NX2 has a new release out today that is further tuning their RAW converter's color balance too.  If you want odd coloration's, use another conversion program.

Interesting learning experience, and made me more apprehensive of using Capture One as well.

SG
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Justinr on February 04, 2014, 02:30:33 pm
Couple of things in your NEF files.

One is that you are all over the place in your "Picture Control" settings.  The woman is set for "Monochrome" (??). The girls are set as "Landscape" (Which is far more vivid.).  Also, you might want to pull the red back to the left in the histogram of girls shot by setting using your camera's Active-D lighting set to "Low" in Capture NX2.  This is done using Capture NX2 which you should be using to see what you are doing as you are all over the place in settings.  None of the other RAW processors are going to see this, nor know how to deal with it.  There is a difference and why Nikon recommends their software for initial post work.  I would hope their engineers know a bit more than the other software converter makers, Adobe included.

For fun, I also opened the woman's image in Capture One 6 and it is really saturated on color (and heavy towards an orange) verses Capture NX2 which looks far more natural.  Not a pleasant way to go on initial processing.  Adobe's 8.3 RAW and DxO Optics Pro 9 aren't as heavy on color saturation as CO, but both are warmer and more saturated than Capture NX2 which seems very neutral and natural.  No doubt there could also be an issue with Apple's Colorsync too if you use a Mac which always seems to mess up something or some driver matter with each version.

Aside, I'll agree with the D800 camera's LCD not being all that pleasant to look at over the Canon's LCD screen.  In studio it looked awful on the LCD prior to the last firmware update.  The Canon looked far better side-by-side.  My D800 had a sickly cyan/green color under studio lights, but the images were always good in post.  It looks warmer since the firmware update.  But I don't rely on it for an accurate representation as it cannot do that.  It ain't an Eizo screen!

These were out of the D800E.  The girl's costume is a bright red Shantung satin fabric that has a faint texture. The texture is still there.  Just have to watch exposure and the Active-D lighting control (and utilization in Capture NX2) to keep it there.

http://24.media.tumblr.com/2c8ef2fcbbbd6f7408c296a6e21ee626/tumblr_mp6h4dmzjH1s9g2zzo2_1280.jpg (http://24.media.tumblr.com/2c8ef2fcbbbd6f7408c296a6e21ee626/tumblr_mp6h4dmzjH1s9g2zzo2_1280.jpg)

Her skin coloring, although powdered by a MU person:

http://24.media.tumblr.com/2b3df062647757df7f0ca003f9d11adb/tumblr_mp6gtjvk441s9g2zzo2_1280.jpg (http://24.media.tumblr.com/2b3df062647757df7f0ca003f9d11adb/tumblr_mp6gtjvk441s9g2zzo2_1280.jpg)

Try and standardize your shooting control (maybe "Normal"), check your camera's exposure to see if it is leaning towards overexposure (All my Nikon's do for some reason so I set a minus value into them.), and use a decent converter that shows you what the camera was set on and doing (i.e. Capture NX2).  Capture NX2 has a new release out today that is further tuning their RAW converter's color balance too.  If you want odd coloration's, use another conversion program.

Interesting learning experience, and made me more apprehensive of using Capture One as well.

SG


Having seen those two images (esp the first one) it looks as if I'm going to have to stop messing about with freebie convertors and and do a proper job with NX2. Lovely work.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Fine_Art on February 04, 2014, 04:22:51 pm
The picture of the woman is actually significantly underexposed. In RT setting it on neutral moves the clipped edge of her fingernail below the 3/4 line on the histogram. Setting Auto levels moves exposure to +1.12

More importantly for your red clipping, the only way I can get it to do that is to set temp to cloudy which moves it to over 6000 kelvin. Then the red clips and she looks orange. If you set your color to camera she has a mild tan. If you set it to AWB she looks more typical for pale far north skin.

You need to fix your settings.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Vladimirovich on February 04, 2014, 04:58:45 pm
This image is exposed 1.14 stops below clipping of the Green CFA channels
PS: one Iliah Borg does not like moving close to clipping with D800(e), something like not within 1 stop of that...
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: LKaven on February 04, 2014, 07:44:34 pm
The picture of the woman is actually significantly underexposed. In RT setting it on neutral moves the clipped edge of her fingernail below the 3/4 line on the histogram. Setting Auto levels moves exposure to +1.12

More importantly for your red clipping, the only way I can get it to do that is to set temp to cloudy which moves it to over 6000 kelvin. Then the red clips and she looks orange. If you set your color to camera she has a mild tan. If you set it to AWB she looks more typical for pale far north skin.

You need to fix your settings.

Again, I suspect the choice of tone curve and profile has something to do with what the OP is getting.  A "standard" curve will not only push the highlights, but make the bunch up a bit.  The "portrait" profile is better in just this one way.  But the "neutral" or "linear" or "camera linear" profile is the only one that tells you what the real exposure was, and will deliver neutral tones.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Lorenzo Pierucci on February 05, 2014, 10:37:57 am
http://www.youtube.com/watch?v=dWaFDKrNrwc

High Rez
http://digitaldog.net/files/SkinToneVideo.mov

Great for this! Thanks so much
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Lorenzo Pierucci on February 05, 2014, 10:58:37 am
Ok guys, as always u had prove to be the best source on the net, thanks for all the sharing.

Ok so there is a error on my camera setting to. I do menage to use the the "picture control" on camera but not that much, because i know that in C1 and CRAW they will not care about it. So i don't really care, but looks that i should. Is the Standard the best setting to go for skin ? The portrait one looks so low contrast and low saturation that turn pale skin to gray…. :-\

Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Some Guy on February 05, 2014, 11:38:26 am
Lorenzo, I found this recent thread in ModelMayhem on the D800 & Capture One: http://www.modelmayhem.com/po.php?thread_id=915857 (http://www.modelmayhem.com/po.php?thread_id=915857).  Seems the guy in the thread, Fred Greissing, got a response from Capture One (halfway down the thread) on the orange/brown color cast using their software with the D800 (i.e. "...but the brown-tinted tone of CO is deliberate choice based on user input.").  With my own little test using it yesterday, I wouldn't use it for RAW conversion out of the D800 unless I liked saturated orange/brown skin.  Those mayhem guys may be more finicky with skin color so maybe they are on to something too with Capture One and the D800.

I find the "Portrait" to be much like what you found, soft.  Maybe if you have someone with blown out forehead highlights or oily skin, but the Active-D lighting goes a long way in fixing some of that.  Just leave it in "Standard" or "Normal" and try a color chart and get as close as you can with the settings in the camera.  To fully utilize all those settings you are back to using Nikon's software.  Imho, even Adobe ACR is sort of like a Swiss Army Knife: It tries to do a lot, but not necessarily the best for the job at times for a given camera.

Personally, I hated Capture NX2 when I bought it 2-3 years ago.  It crashed a lot and was very slow.  Seems it is getting better with each version though and it recently went 16 bit.  Takes a lot of RAM though when running.  Maybe not as much as DxO Optics Pro 9 which really can beat a computer down with its PRIME noise reduction.  Still, Capture NX2 does seem to be the best NEF conversion out there for Nikon as it reads the camera files far better than anything else, but I expect it should be too.  Uses the Nikon RGB 4 colorspace too which seems to have some red control applied.  It also has those "Control Points" where you can fix certain contrast/color/brightness issues on an assigned portion of an image which is nice.  I like their retouch tool too that seems to leave some texture in the spot rather than going to Adobe plastic look.

SG
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: digitaldog on February 05, 2014, 11:58:04 am
Ok so there is a error on my camera setting to.
Yes and no. Yes IF you use the Nikon software that can understand and presumably produce a useful rendering from camera settings (picture styles you set on that camrea). Otherwise, raw is raw. It's why you can't separate the processing from the capture. If you take the same NEF and hand it to Lightroom, or C1, those camera settings, which are just metadata and have zero effect on the raw data itself is ignored.

Decide what raw converter you'll use, then you can deal with how it processes the raw data and the result of the final rendering. If you use Nikon's software, the settings referenced are important. If you don't use that converter, they are of no use and have no bearing on the data or the processing.

Keep in mind, the raw data is far closer to a grayscale document than anything else, the over donered color you see, if not an attribute of the display calibration is an attribute of the processing in large part. And again, in the NEF you provided, in Lightroom, the skin tones seem OK and look OK, your exposure is 'down' and you're not anywhere near color or tone clipping at least as reported though the ACR engine. Pop that raw into another converter, you will probably see something quite different.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: LKaven on February 05, 2014, 12:35:28 pm
I do menage to use the the "picture control" on camera but not that much, because i know that in C1 and CRAW they will not care about it. So i don't really care, but looks that i should. Is the Standard the best setting to go for skin ? The portrait one looks so low contrast and low saturation that turn pale skin to gray…. :-\

I responded twice on this question: The "standard" profile is designed to exaggerate color in a "pleasing" sort of way.  It is not suitable for portraits.  If you want real skin color, this is not the profile to use.  Plus it blows your highlights.

The "portrait" profile is design to mitigate just this thing in skin tones.  But it does not go far enough. 

If you want real skin tones, you need to start with the "neutral" profile and roll your own tone curve with suitable care.  Yes, the "neutral" setting looks flat; it's just the starting point. 
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: digitaldog on February 05, 2014, 12:53:16 pm
I responded twice on this question: The "standard" profile is designed to exaggerate color in a "pleasing" sort of way.  It is not suitable for portraits.  If you want real skin color, this is not the profile to use.  Plus it blows your highlights.
Not in Lightroom, not with the image the OP supplied. Nothing even close to highlight's blowing out. Now in another converter, possible. But the OP mentioned Lightroom and the profiles there really have no role over highlight's blowing out or not.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Vladimirovich on February 05, 2014, 01:08:41 pm
But the OP mentioned Lightroom and the profiles there really have no role over highlight's blowing out or not.
dcp profiles can control hidden expocorrections, WB, color transforms... so dcp profile can contribute to any number of ill effects... now if you are talking about profiles supplied by Adobe and without extreme manipulations in LR UI with a regular image that's another story
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: LKaven on February 05, 2014, 01:52:53 pm
Not in Lightroom, not with the image the OP supplied. Nothing even close to highlight's blowing out. Now in another converter, possible. But the OP mentioned Lightroom and the profiles there really have no role over highlight's blowing out or not.

Thought he was using C1.

The "standard" profile -- in every converter -- should be called the "pimped-out color" profile.  That way, nobody would ever be tempted to write "I used the pimped-out color profile, and the colors don't look accurate.  Why?"

The "neutral"/"linear" profile is great.  Start with the cleanest numbers, then customize your tone curve and local contrast enhancements altogether.  Too many people waste their time trying to 'unscrunch' their tones in photoshop after telling the computer to scrunch them up in capture.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: digitaldog on February 05, 2014, 01:55:26 pm
now if you are talking about profiles supplied by Adobe and without extreme manipulations in LR UI with a regular image that's another story
That's exactly what I'm talking about and observed with the supplied NEF.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: digitaldog on February 05, 2014, 01:59:12 pm
Thought he was using C1.
He's using at least three converters. So the first step is deciding which to use as I don't see how we can separate the processing from the capture.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Some Guy on February 05, 2014, 02:08:13 pm
.... in the NEF you provided, in Lightroom, the skin tones seem OK and look OK, your exposure is 'down' and you're not anywhere near color or tone clipping at least as reported though the ACR engine. Pop that raw into another converter, you will probably see something quite different.

No doubt you will see something different from various converters.  Messing around and I just did.

In Nikon's ViewNX 2, the reds are definitely overexposed with the girls and especially their red (neon) basket, as are her red fingernails and the strawberry with no texture.  The basket is even shown being blown out in Windows Photo Viewer alone with the NEF.  Pull it up in CaptureNX 2 on the Red channel alone and it is blown at each end - but much worse on the highlight end with a very steep over-exposure spike there too.  I'll see if I can post a histogram image of it shown being blown out in CaptureNX 2.

Oddly, in ACR 8.3 it is not blown in their default histogram and seems compressed in range too.  Seems Nikon and Adobe are at a disagreement there, and why I'm not fond of Adobe for RAW conversion much less analysis with the D800.  Adobe sort of blew it there, but they are the generic Swiss Army Knife so I cut them a little slack - just not to use it for critical conversion with the D800 especially when reds are around.

Most of what the OP needs to do is focus and not jump all around the place in settings and converters.  Try and nail the reds down with some converter (Active D lighting perhaps) and all should fall in line - maybe.

SG
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: digitaldog on February 05, 2014, 02:14:04 pm
Quote
In Nikon's ViewNX 2, the reds are definitely overexposed with the girls and especially their red (neon) basket, as are her red fingernails and the strawberry with no texture.
Oddly, in ACR 8.3 it is not blown in their default histogram and seems compressed in range too.  Seems Nikon and Adobe are at a disagreement there
Looks like saturation clipping but I don't know that product. We need to examine a "luminosity"(it's actually brightness) histogram if one exists. It's easy to show saturation clipping on an image in say ACR when set to encode in sRGB which completely disappears if we select ProPhoto RGB instead. So in terms of what the histogram tells us, and they are prone to lie, it's possible there's no clipping anywhere within the raw data and it is the rendering controls at play here.

In ACR, if you convert to grayscale, you'll get close to the "luminosity" histogram in Photoshop. Close but not spot on due to the role of the data and processing in that converter. ACR and LR only provide RGB histograms which tell one part of the story and not the other.
Quote
Most of what the OP needs to do is focus and not jump all around the place in settings and converters.  Try and nail the reds down with some converter (Active D lighting perhaps) and all should fall in line - maybe.
Agreed although depending on the converter, many of the camera settings will play no role.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Lorenzo Pierucci on February 06, 2014, 04:31:16 am

The "standard" profile -- in every converter -- should be called the "pimped-out color" profile. 

HAHAHAHA so true.

Ok, i just play around a bit. Looks like the "picture control" have a part on the mess. Im now shoot in "neutral" ( which i guess is linear response ) and i get something quite similar to what i get when i import file in C1, also thanks the suggestion of use the linear curve, the similitude is even greater. Lets say that image does not looks great straight away, but at least I'm now seeing what i will get on the converter.

I use C1 for skin work, CRaw for architectural. I now start to menage this Rawtherapee which looks pretty cool. LR seems really to simple to me.

You guys had share a lot of knowledge really appreciated.

I just wish that my straight from camera LCD will look a bit better ( especially when shooting not tethered with client ). I always have to say " here looks suck but on screen will be great". I start to believe that Canon have a definitely better LCD display….  :-\
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: hjulenissen on February 06, 2014, 04:38:54 am
...
The "standard" profile -- in every converter -- should be called the "pimped-out color" profile.  That way, nobody would ever be tempted to write "I used the pimped-out color profile, and the colors don't look accurate.  Why?"

The "neutral"/"linear" profile is great.  Start with the cleanest numbers, then customize your tone curve and local contrast enhancements altogether.  Too many people waste their time trying to 'unscrunch' their tones in photoshop after telling the computer to scrunch them up in capture.
For my Canon 7D and Adobe Lightroom, none of the included profiles worked out for me (reds seems to have wrong hue and saturation).

It is strange that they won't do one default profile that is somewhat neutral under most lighting conditions, and rather have a slider called "pimp out my color". If need be, set this slider to 100% as default (this would be a lot more transparent).

-h
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Lorenzo Pierucci on February 06, 2014, 09:13:13 am
Ok i tried out the liner of C1, looks that every shoot need to be over exposed of 1.5 stop, coz they all looks underexposed after apply the linear response. While on camera they looks well exposed.

But indeed: Linear response gave me better control ( looks like )
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: sandymc on February 06, 2014, 10:21:33 am
Out of curiosity, I took a look at both images in AccuRaw, which by design doesn't have any of the hue twists, "pimped up profiles", etc, and is generally very linear in its color response. AccuRaw agrees with Nikon's View NX  :) - in the second image, the red channel is blown. Although the rendered image looks ok. The first image looks fine - both on histogram and as rendered.

Sandy
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Bart_van_der_Wolf on February 06, 2014, 11:54:41 am
Out of curiosity, I took a look at both images in AccuRaw, which by design doesn't have any of the hue twists, "pimped up profiles", etc, and is generally very linear in its color response. AccuRaw agrees with Nikon's View NX  :) - in the second image, the red channel is blown. Although the rendered image looks ok. The first image looks fine - both on histogram and as rendered.

Hi,

The Red channel in the second image is not really blown, not even after white-balancing, but it is very saturated (Red near 65% Green near 0%). A minor (-8) tweak in RawTherapee's CIE2002 Chroma (JC) brings everything into reasonable ranges, and allows to boost exposure by +0.91EV without introducing any clipping.

I'm more puzzled by the Green channels, the green bag also showed zero values, suggesting saturation/gamut clipping. I do not know how good the default profile for the D800 is, but skin tone looks just fine.

Cheers,
Bart
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: digitaldog on February 06, 2014, 12:35:50 pm
Ok i tried out the liner of C1, looks that every shoot need to be over exposed of 1.5 stop, coz they all looks underexposed after apply the linear response. While on camera they looks well exposed.
Just ignore what you see on the camera LCD! In terms of exposure (for raw), clipping etc, it's a big fat lie. Great for checking focus, composition but pretty worthless for anything that releates to the raw data.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Lorenzo Pierucci on February 06, 2014, 12:38:26 pm
Just ignore what you see on the camera LCD! In terms of exposure (for raw), clipping etc, it's a big fat lie. Great for checking focus, composition but pretty worthless for anything that releates to the raw data.

So true! Film era docet.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: LKaven on February 06, 2014, 01:15:05 pm
Ok i tried out the linear of C1, looks that every shoot need to be over exposed of 1.5 stop, coz they all looks underexposed after apply the linear response. While on camera they looks well exposed.

But indeed: Linear response gave me better control ( looks like )

C1 with the linear profile is giving you the closest to the actual numbers from the sensor.  So now you know where you really are!

The camera will apply all of the picture controls and JPG settings to the preview.  The in-camera histogram reflects in-camera settings.  In fact, the preview itself is a "basic" in-camera JPG. 

A good approximation of true exposure on the camera is to set picture control to "neutral" and WB to 5600K.  The rear LCD on the D800 isn't calibrated either (as it is on the D3/s/D4).  I find it best at around -1 brightness, but your experience might be different.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Lorenzo Pierucci on February 06, 2014, 02:01:25 pm
I find it best at around -1 brightness, but your experience might be different.

Thanks! that was something i was wondering about actually. Putting this setting straight away !
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Lorenzo Pierucci on February 07, 2014, 07:47:59 am
Dear Luminous Lasndscapers,

at the end this topic and the experience i did for this had make me totally change my way of shooting. Now: i realize that i m not that good as the camera give me the exact linear raw and don't "cheat". It gave me the same impression of film, so that i have to adjust lighting in order to get a good raw.

Many thanks, that s is a turning point
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: MarkM on February 09, 2014, 04:46:55 pm
Here's a video on correcting skin tones without having to resort to CMYK using Adobe raw converters:

Low Rez (YouTube)
http://www.youtube.com/watch?v=dWaFDKrNrwc

High Rez
http://digitaldog.net/files/SkinToneVideo.mov

Great videos, Andrew.

Maybe it's common knowledge by now, but just in case everyone hasn't figured it ou, you can now get LAB values in Lightroom 5 by right clicking the histogram in the develop module.

Also, I wish I lived somewhere where the a* and b* star values of skin tones where in the mid 20s. With no sun this time of year, everyone looks like vampires unless you cake them with makeup.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: G* on February 11, 2014, 12:02:20 pm
Just three more hints:
#1: You can copy the .icm profile that Capture NX2 generates when developing a .NEF file and put in CaptureOne (use linear tone curve then!). This way you get a NX2 color palette and CO demosaicing + GUI + performance. Just be careful with the camera’s settings: NX2 will interpret them and build its .icm profile accordingly. You might want to produce different profiles for different settings and lighting situations.
#2: It’s true that other converters than NX2 won’t understand the camera’s setting – exept for D-Lighting which directly affects exposure!
#3: Since now you understand that the in-camera preview file (that is shown on the rear LCD, is affected by in-camera settings, is the basis for the in-camera histogram) will not show the colors and the tone curve of your developed RAW file (and it’s limits/possibilities!), you might as well tweak it so that it’s at least a good indicator for exposure and clipping. Have a look at Jim Kasson’s take on that topic: http://blog.kasson.com/?page_id=2387
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: D Fosse on February 11, 2014, 02:20:29 pm
Quote
You can copy the .icm profile that Capture NX2 generates when developing a .NEF file and put in CaptureOne

By now I've read this five times and it still makes no sense. What are you talking about?
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: bjanes on February 11, 2014, 02:32:42 pm
PS: one Iliah Borg does not like moving close to clipping with D800(e), something like not within 1 stop of that...

I have not found that to be a problem with my D800e but greatly respect Iliah's opinion. Can you provide a link to reference Iliah's findings?

Thanks,

Bill
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: G* on February 11, 2014, 03:27:57 pm
@ D Fosse:

I can tell you what I do on my Mac:

- Preparation: Make invisible folders and files in the finder visible: Start the Terminal app: Copy/paste "defaults write com.apple.finder AppleShowAllFiles TRUE;killall Finder": Push the return-button. Quit.
- Open a *.NEF file with Capture NX2
- Have a look at the folder *main volume*/private/temp in the Finder ("private" is one of the formerly "invisible" folders).
- Search for the folder "Nkn****" that has been created when you started Capture NX2. Look inside.
- You will find an *.icm file that has just been generated by Capture NX2. As much as I know it is uniquely tailored to the opened *.NEF file, its ISO, its WB, its picture control settings, whatever. Its name will be rather cryptic, but you might identify the name of your camera as part of the string. Anyway, copy that file.
- Paste it in the ColorSync/Profiles folder (*main volume*/*user*/*your user*/Library/ColorSync/Profiles).
- Name it according to CaptureOne’s rules, i.e. begin with the Name of your camera. For example "NikonD800-*********". Whatever comes after the "-" may be to your liking. You can quit Capture NX now, btw.
- Next time you start CaptureOne you will be able to choose the new profile from the drop-down menu "icc profile". Since a tone-curve is already part of the profile you better choose "linear response" instead of the CO film-curves.

That’s it. Sounds more complicated than it is.
Should work also with ViewNX software, which is free.
All information is provided without guarantee. Please be careful with your machine, get someone you trust to help you if you’re afraid to damage your computer. I have no idea what the steps would be on a Windows machine.
To hide the hidden folders and files again use the line "defaults write com.apple.finder AppleShowAllFiles FALSE;killall Finder" in Terminal.

Does it make sense? That depends. I like the colors I get using the NX2-profiles in CaptureOne. To my eye they’re better than CaptureOne’s generic profiles. And I don’t have the means to make really good profiles on my own. YMMV
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: D Fosse on February 11, 2014, 05:39:57 pm
Does it make sense?

Disclaimer: I only use Lightroom and I'm not familiar with Capture NX or Capture One.

But here's the part I still don't understand: Why would a raw converter use .icc/.icm profiles at all - aside from the direct chain from the converter's internal working space to the display profile? There are no other profiles or color spaces in the loop, not that I know of, not in Lightroom. The camera profiles are not icc profiles.

So the only way I can make sense of what you wrote is to conclude that you somehow manage to dissect and extract an icc profile that describes the converter's internal working color space. But why would that be "individually tailored to each file"?

I still don't get this. This is contrary to everything I (thought I) knew about raw converters. Maybe I'm missing something. Andrew? Jeff?

BTW I've never had any problems with red clipping or skin tones in my D800, so I'm just watching this thread out of curiosity.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: digitaldog on February 11, 2014, 05:56:55 pm
But here's the part I still don't understand: Why would a raw converter use .icc/.icm profiles at all - aside from the direct chain from the converter's internal working space to the display profile? There are no other profiles or color spaces in the loop, not that I know of, not in Lightroom. The camera profiles are not icc profiles.
There are (presumably) no other color profiles in the loop but there are color space assumptions along the line. And some internal color processing space (ProPhoto primaries in the one converter I can speak about, ACR/LR).
As for as other converters that use ICC profiles, ICC profiles are output referred. That means this profile 'defines' a rendered and processed data. Something LR/ACR doesn't do with it's profiles. Just to build an  ICC profile, you have to hand off a processed TIFF or similar to the profile building application. A lot of the cake has been baked so to speak, a lot of the ingredients are undefined. I don't know what G* is referring to as I like you only work with LR/ACR. But if this is an ICC profile, it's defining the entire process or a lot of it, up to the point you've got some data you can send as a rendered image to a profile creator. That means a lot of what happens in the converter isn't 'defined' but the final data is supposed to be.

Title: Re: D800 clipping red channel ? Any possible solutions
Post by: kers on February 11, 2014, 07:25:08 pm
...
I can tell you what I do on my Mac:
....
- Next time you start CaptureOne you will be able to choose the new profile from the drop-down menu "icc profile". Since a tone-curve is already part of the profile you better choose "linear response" instead of the CO film-curves.
....

hello G*,

interesting to read something about how Nikon deals with their NEF's .
I suppose you can use this method ony with CaptureOne ?  for i did not manage to load it in ACR , or another raw converter..

and speaking about NEFS; do you happen to have a methode to quickly set free the jpeg's from the NEFS?

i did have a programm that did it very well but it stopped working in 10.9 mavericks, alas

(that program is called IJFR by Micheal Tapes  -http://michaeltapesdesign.com/instant-jpeg-from-raw.html)

Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Vladimirovich on February 12, 2014, 02:42:13 am
Just to build an  ICC profile, you have to hand off a processed TIFF or similar to the profile building application.
no, you don't... why spread FUD ? for example use RawDigger CGATS output and so on...
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: D Fosse on February 12, 2014, 04:14:28 am
All right, now I had to google CGATS, just to show how much I know...but as far as I can tell, CGATS is just a protocol for exchanging color data. It doesn't alter the basic fact:

Quote
ICC profiles are output referred

So as I see it, an icc profile requires rendered data. And in Lightroom/ACR at least, this doesn't happen until the raw file is encoded into linear ProPhoto - after the raw file has been demosaiced, and after the camera profiles.

From linear ProPhoto, it's a single step to the display profile, or the printer profile, or the export color space. These are all (output referred) icc profiles.

Or is this just FUD?
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: G* on February 12, 2014, 06:40:23 am
I am the last person to ask for what’s going on under the hood of NX2 or CO, really. I did not invent this method, either. I picked it up somewhere on the web during my search for alternative color palettes out of CO. All I can say is that my experience is quite positive, so far I have not encountered major problems. But I’m no pro, my time for photography is pretty limited. It would be interesting for me to hear what others think of this method, too.

As for the LR/ACR users: My understanding is that Adobe has chosen a completely different path to incorporate profiles, probably because their rendering engine follows a different path, too. They use DNG profiles which you can build quite easily by yourself on the basis of ColorChecker shots. Since I’m not overly familiar with LR/ACR I will leave further comments on this system and how it compares with other methods to the more versed.

@kers:
I really can’t say if there are other converters than CaptureOne with which this method works – I am only guessing that there should be some. But I’m pretty sure that there is a profound difference between CO and ACR/LR that precludes from using this method with Adobe software.
I have never tried to unhinge the preview JPGs from a NEF file. I was thinking that they were probably pretty small anyway.

Title: Re: D800 clipping red channel ? Any possible solutions
Post by: D Fosse on February 12, 2014, 06:58:24 am
Well, you obviously found something. I'm just trying to figure out what it can be.

Maybe what you found is what Andrew calls "color space assumptions along the line". Something similar to Lightroom's camera profiles, but using a different framework.

And of course we're talking about different converters. Perhaps someone more familiar with the inner workings of NX or C1 can shed some more light on it.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: kers on February 12, 2014, 09:08:01 am

@kers:
...
I have never tried to unhinge the preview JPGs from a NEF file. I was thinking that they were probably pretty small anyway.
...

No, as you can imagine they are full size ( otherwise you could not zoom in@100% using RAW ) but are compressed to about 2-3 MB size.
And with IJFR releasing them takes no time at all. So you can make more pictures on your card.(Now i shoot RAW + small fine jpeg )
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: bjanes on February 12, 2014, 09:39:49 am
As for as other converters that use ICC profiles, ICC profiles are output referred. That means this profile 'defines' a rendered and processed data. Something LR/ACR doesn't do with it's profiles. Just to build an  ICC profile, you have to hand off a processed TIFF or similar to the profile building application. A lot of the cake has been baked so to speak, a lot of the ingredients are undefined. I don't know what G* is referring to as I like you only work with LR/ACR. But if this is an ICC profile, it's defining the entire process or a lot of it, up to the point you've got some data you can send as a rendered image to a profile creator. That means a lot of what happens in the converter isn't 'defined' but the final data is supposed to be.

I don't understand why you make such a sharp distinction between scene and output referred files. The output referred file is tone mapped, usually with a compression of the dynamic range, and gamma encoded. The scene referred file is a linear representation of the actual scene. I can render a Colorchecker into LinearRIMM Ver 4 as outlined by this ICC paper (http://www.color.org/scene-referred.xalter) as scene referred. The graph shown below is a plot of the bottom row of the monochrome patches, and confirms linearity. Viewed in a non color managed application, it looks dark but it appears normal when viewed in Photoshop. I can hand off this scene referred file to any ICC profile for output.

Regards,

Bill

Title: Re: D800 clipping red channel ? Any possible solutions
Post by: digitaldog on February 12, 2014, 10:32:50 am
no, you don't... why spread FUD ? for example use RawDigger CGATS output and so on...

FUD? What got you panties tied in a knot?  :-\
And I could build a CGATs file from rendered data too, the point is, you are not sending raw data to an ICC profile creator, you're sending some "processed" RGB data to the profile creator. Forgive me for specifying one has to send a rendered TIFF or similar to a profile creator. OK, you can send what is basically a text file too (which defines processed RGB data).

I don't understand why you make such a sharp distinction between scene and output referred files. The output referred file is tone mapped, usually with a compression of the dynamic range, and gamma encoded. The scene referred file is a linear representation of the actual scene. I can render a Colorchecker into LinearRIMM Ver 4 as outlined by this ICC paper as scene referred. The graph shown below is a plot of the bottom row of the monochrome patches, and confirms linearity. Viewed in a non color managed application, it looks dark but it appears normal when viewed in Photoshop. I can hand off this scene referred file to any ICC profile for output.

I agree, I'm simply pointing out the vast differences between actual raw data, what may be scene referred data and output referred data, the later more heavily processed data and for some, easier to get at (scene referred more difficult to get to).

This is explained by the ICC in the following paper:

Using ICC profiles with digital camera images:

There is also the case where a camera puts out files containing raw or scene- referred image data. If the raw image data results from capture using a color filter array (e.g. the red, green and blue color values are captured by different pixels), a special camera raw processing application is needed to create a viewable color image. In most cases, these applications (for example Adobe Photoshop camera raw) create standard output referred images, as would the camera.


http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDIQFjAB&url=http%3A%2F%2Fwww.color.org%2Ficc_white_paper_17_icc_profiles_with_camera_images.pdf&ei=eYv7UrWzMsiErQHDiYDwDg&usg=AFQjCNG7OE45m9ZbE6bGh1iiAYWtWcyqqg&sig2=Y1TFJYW2luEFGze9eZzhaA&bvm=bv.61190604,d.aWM

Here's some further data to chew on from Erick Walowit (this is from the ColorSync list way back in 1998, has anything changed?):

Quote
All v2 ICC colorimetry is picture-referred and may assumed to be
output-referred. This means that all v2 ICC rendering intents represent the colorimetry
of the desired reproduction, not the scene. Yep, even for the colorimetric
rendering intent.
B) v4 was silent on image state so most assume that v4 also represents
output-referred colorimetry.
C) In v2, v4, and many other non-ICC profiling methods, there is no way that
I knew of to commmunicate weather the colorimetry is scene-referred or
output-referred. This means you have to assume its output-referred, the colorimetry
of the reproduction, not the scene.
D) For this reason, I introduced the "colorimetric intent image state" tag
for v4 profiles. It was approved by the ICC last year and will hopefully start
showing up in camera profiles in the future. If you have a v4 profile with the
image state tag set to one of the scene-referred values, then you know the
profile represents the colorimetry of the scene instead of the desired
reproduction. Otherwise you have to assume the colorimetry is output-referred.
E) It is perfectly understandable that v2, v4, and non-ICC profiles produce
output-referred colorimetry: most workflow demands it. Is only been relatively
recently (RAW) that applications are starting to understand the value of
scene-referred colorimetry. But many RAW workflows also use output-referred
profiles for the sake of productivity.
F) So, in the general case, you have no way of knowing if a given profile
(ICC or otherwise) is intended to produce scene-referred or output-referred
colorimetry.
G) But lets suppose you have a given profile and you know it is
scene-referred, then you are good to go, right? Wrong, for many reasons. Here is just one
example: No shipping camera that I know of meets the Luther-Ives condition. The
means that cameras exhibit significant observer metamerism with respect to
humans. So the scene-referred profile designer must decide how to optimize the
profile. Two possible extremes: i) minimize the color differences of a color
chart, or ii) minimize the color differences of representative scene spectra. If
i) is chosen then the profile will perform optimally on the chart but
suboptimally (not necessarily poorly) on real scenes. Poor choice. If ii) is chosen
then the profile will perform optimally on the scene but suboptimally (and
frequently quite poorly) on color charts. Better choice. If you have any doubt
about this, derive and compare the basis functions for color charts and scene
spectra. ISO 17321 is a good place to start. There is a third possibility
somewhere in the middle. Use a photograph of a color chart to learn something about
the camera colorimetry but influence the profile based on scene-spectra consi
derations. OK choice.

Maybe since 2008, this is changed (Eric's update to the V4 spec, cameras that meet Luther-Ives condition?).
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Vladimirovich on February 12, 2014, 11:03:01 am
FUD?

yes, you are with vested interests in Adobe's suite of tools

And I could build a CGATs file from rendered data too

yes, but you can do it w/o rendered output of raw converter - that is the point that you try to hide

, the point is, you are not sending raw data to an ICC profile creator, you're sending some "processed" RGB data to the profile creator.

and so you can say about "dcp" (Adobe DNG profiles) profiling :-) ...  Adobe DNG PE does work with no less rendered data than rawdigger - so ?
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: Vladimirovich on February 12, 2014, 11:06:57 am
This is explained by the ICC in the following paper
using ICC as a data container for input profiles does not mean everybody does them like ICC (organization) says so
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: digitaldog on February 12, 2014, 11:15:20 am
yes, you are with vested interests in Adobe's suite of tool
Please elaborate. Because you don't know WTF you're talking about. What vested interest?
Quote
yes, but you can do it w/o rendered output of raw converter - that is the point that you try to hide
I'm not trying to hide anything. You on the other hand seem to be hiding (here) behind an anonymous alias while my transparency is pretty clear. Pot calling the kettle black!
Quote
and so you can say about "dcp" (Adobe DNG profiles) profiling :-)
Absolutely I never said otherwise. The data is quite different, as is the processing.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: digitaldog on February 12, 2014, 11:16:22 am
using ICC as a data container for input profiles does not mean everybody does them like ICC (organization) says so
Sure, what do they know.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: bjanes on February 12, 2014, 11:21:33 am
I agree, I'm simply pointing out the vast differences between actual raw data, what may be scene referred data and output referred data, the later more heavily processed data and for some, easier to get at (scene referred more difficult to get to).

This is explained by the ICC in the following paper:

Using ICC profiles with digital camera images:

There is also the case where a camera puts out files containing raw or scene- referred image data. If the raw image data results from capture using a color filter array (e.g. the red, green and blue color values are captured by different pixels), a special camera raw processing application is needed to create a viewable color image. In most cases, these applications (for example Adobe Photoshop camera raw) create standard output referred images, as would the camera.


Here's some further data to chew on from Erick Walowit (this is from the ColorSync list way back in 1998, has anything changed?):

Maybe since 2008, this is changed (Eric's update to the V4 spec, cameras that meet Luther-Ives condition?).

Thanks for the link and info. I don't know if anything has changed or not. Of course the file that I called scene referred is not truly scene referred since no camera meets the Luther-Ives conditions and metameric errors will be introduced. Also flare will reduce the dynamic range. Thus, it is scene referred with limitations.

A simpler way to obtain scene referred data is to change the mode in Photoshop to 32 bit floating point. Starting with ProphotoRGB, the resulting profile listed for the file is "Prophoto RGB (Linear RGB Profile)". Photoshop will not print this file, but it can be imported into Lightroom and printed from there with the usual paper ICC profiles.

Bill
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: digitaldog on February 12, 2014, 12:15:40 pm
A simpler way to obtain scene referred data is to change the mode in Photoshop to 32 bit floating point. Starting with ProphotoRGB, the resulting profile listed for the file is "Prophoto RGB (Linear RGB Profile)". Photoshop will not print this file, but it can be imported into Lightroom and printed from there with the usual paper ICC profiles.
By virtue of being 32-bit linear, is it truly scene referred?
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: bjanes on February 12, 2014, 03:18:38 pm
By virtue of being 32-bit linear, is it truly scene referred?

Only if the file converted to 32 bit is scene referred. In this case, I used ACR PV2012 with a linear tone curve and rendered into ProphotoRGB and then converted to 32 bit. Converting to untagged linear with ImagesPlus gives a very similar curve, confirming that the rendering is linear. These plots are the bottom patches of the Colorchecker. The ACR conversion is preferable, since it does render into a defined color space, whereas the ImagesPlus is untagged RGB.

Sometimes it is good to have a linear file for photometric measurements and the images are scene referred within the limitations of the CFA sensor.

Bill

Title: Re: D800 clipping red channel ? Any possible solutions
Post by: digitaldog on February 12, 2014, 04:19:56 pm
In this case, I used ACR PV2012 with a linear tone curve and rendered into ProphotoRGB and then converted to 32 bit. Converting to untagged linear with ImagesPlus gives a very similar curve, confirming that the rendering is linear. These plots are the bottom patches of the Colorchecker. The ACR conversion is preferable, since it does render into a defined color space, whereas the ImagesPlus is untagged RGB.

So what's your take based on the above and this definition of scene referred from the ICC?

Quote
scene-referred image data
image data which represents estimates of the colour-space coordinates of the elements of a scene. [ISO 12231]
NOTE 1 Scene-referred image data can be determined from raw DSC image data before colour rendering is performed. Generally, DSCs do not write scene-referred image data in image files, but some may do so in a special mode intended for this purpose. Typically, DSCs write standard output-referred image data where colour rendering has already been performed.
NOTE 2 Scene-referred image data typically represents relative scene colorimetry estimates. Absolute scene colorimetry estimates may be calculated using a scaling factor. The scaling factor can be derived from additional information such as the image OECF, FNumber or ApertureValue, and ExposureTime or ShutterSpeedValue tags.
NOTE 3 Scene-referred image data may contain inaccuracies due to the dynamic range limitations of the capture device, noise from various sources, quantization, optical blurring and flare that are not corrected for, and colour analysis errors due to capture device metamerism. In some cases, these sources of inaccuracy can be significant. ISO 17321-1 specifies a DSC/SMI (DSC Sensitivity Metamerism Index), which can be used to estimate the amount of inaccuracy resulting from capture device metamerism.
NOTE 4 The transformation from raw DSC image data to scene-referred image data depends on the relative adopted whites selected for the scene and the colour space used to encode the image data. If the chosen scene adopted white is inappropriate, additional errors will be introduced into the scene-referred image data. These errors may be correctable if the transformation used to produce the scene-referred image data is known, and the colour encoding used for the incorrect scene referred image data has adequate precision and dynamic range.
NOTE 5 Standard methods for the calculation of scene-referred image data from raw DSC image data will be specified in ISO 17321-2.
NOTE 6 The scene may correspond to an actual view of the natural world, or a computer-generated simulation of such a view. It may also correspond to a modified scene determined by applying modifications to an original scene to produce some different desired scene. Any such scene modifications should leave the image in a scene-referred image state, and should be done in the context of an expected colour rendering transform.

And:

output-referred image data
image data which represents the colour-space coordinates of the elements of an image that has undergone colour rendering appropriate for a specified real or virtual output device and viewing conditions. [ISO 12231]
NOTE 1 The output referred image data is referred to the specified output device and viewing conditions. A single scene can be colour rendered to a variety of output-referred representations depending on the anticipated output viewing conditions, media limitations, and/or artistic intents.
NOTE 2 Output-referred image data may become the starting point for a subsequent reproduction process. For example, sRGB output-referred image data is frequently considered to be the starting point for the colour re-rendering performed by a printer designed to receive sRGB image data.


Apologies if this is OT.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: bjanes on February 12, 2014, 06:02:30 pm
So what's your take based on the above and this definition of scene referred from the ICC?
Apologies if this is OT.

I don't have access to the various ISO standards you reference since they cost around US$150 per copy, but can only rely on the ICC paper (http://www.color.org/scene-referred.xalter) regarding obtaining scene referred data via ACR and Photoshop. I did do a brief Google search for ISO 17321 and found two papers that do supply some data of interest.

Link 1 (http://www2.cmp.uea.ac.uk/Research/compvis/Papers/HolmTastlHor_CIC8.pdf)

Link 2 (http://rua.ua.es/dspace/bitstream/10045/981/1/camera_colorimeter.pdf)

The details are quite complicated and beyond my level of expertise, but do indicate that the resulting "scene referred" data that I am obtaining is only an approximation, especially regarding colorimetry. However, the monochrome patches do give linear scene referred responses where the pixel value is proportional to the relative exposure which is derived from the optical densities of the patches converted to reflectance values. The 32 bit files derived from the mode change from 16 to 32 bit floating point are also linear as shown. That is about all I can say. What is your take on the matter?

Regards,

Bill
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: digitaldog on February 12, 2014, 06:10:01 pm
I don't have those ISO papers either but the free PDF from ICC gives some bkgnd on what they consider scene referred (as was Eric's post to the CC list). Perhaps not enough information to extrapolate the full meaning.

My take on the matter based on this is we need to be somewhat careful about what we call scene referred especially if we believes it defines scene colorimtery.

In the end, the process's used either produce results we're happy with or they don't. That's why I take caution using the term 'accurate color'. It does appear some feel the need to jump through extra steps to get a 'rawer' but demosaiced data to begin the edit process, the final results being 'more accurate'. Outside of some (rare) workflows where this may be necessary, I prefer to avoid that and just let the raw converter of my choice produce images as I wish to express them visually.
Title: Re: D800 clipping red channel ? Any possible solutions
Post by: bjanes on February 12, 2014, 06:20:06 pm
I don't have those ISO papers either but the free PDF from ICC gives some bkgnd on what they consider scene referred (as was Eric's post to the CC list). Perhaps not enough information to extrapolate the full meaning.

My take on the matter based on this is we need to be somewhat careful about what we call scene referred especially if we believes it defines scene colorimtery.

In the end, the process's used either produce results we're happy with or they don't. That's why I take caution using the term 'accurate color'. It does appear some feel the need to jump through extra steps to get a 'rawer' but demosaiced data to begin the edit process, the final results being 'more accurate'. Outside of some (rare) workflows where this may be necessary, I prefer to avoid that and just let the raw converter of my choice produce images as I wish to express them visually.

I agree completely, but I still think that it is sometimes useful to have quasi scene referred images for some data analysis. Also some postprocessing is best done with linear data, which is why it is best to do as much as possible in ACR/LR. However, linear data can be useful for use in Photoshop where the needed algorithm is not available in ACR.

Regards,

Bill