Re: Colorsync-users Digest, Vol 13, Issue 76
Adobe products are all about "pleasing" color. Colorimetric accuracy is next to impossible using Adobe products -- and DNG profiles especially.
This is very much incorrect, on assumptions and fact. Please see the documentation for DNG profiles, Camera Raw, and Photoshop. Chris
On Mar 14, 2016, at 3:24 PM, Chris Cox <ccox@adobe.com> wrote:
Please see the documentation for DNG profiles, Camera Raw, and Photoshop.
I have. Many times. Burned many hours over it. And there's a trivial demonstration for why it's useless to even pretend to attempt a colorimetric workflow with Adobe products. To the best of my knowledge, not a single vendor sells _any_ product for building DNG profiles with anything other than a 24-patch ColorChecker, and those products that support a ColorChecker don't let you provide your own measurements for the chart nor SPD information for the actual illuminant the chart is photographed under. And, even if you _do_ somehow manage to create a perfect DNG profile, you're not even theoretically going to get colorimetric accuracy from it unless you light the scene with a perfect D50 simulator -- something that doesn't actually physically exist, of course. Each bullet point in that paragraph is a showstopper, incidentally. And it's only barely scratching the surface. Adobe makes great products for certain types of artistry. But attempting to use Adobe products for anything where colorimetric accuracy is an essential part of the workflow is as insane as attempting to use a Lamborghini to sow crops or racing a farm tractor in Le Mans. Yes, both a Lamborghini and a farm tractor have four wheels and similar operator controls. But only a fool would use the one where the other is called for. Cheers, b&
On Mar 14, 2016, at 4:01 PM, Ben Goren <ben@trumpetpower.com> wrote:
Please see the documentation for DNG profiles, Camera Raw, and Photoshop.
I have. Many times. Burned many hours over it.
Oh -- and, incidentally, Adobe products spectacularly fail many of the simple tests out there designed to demonstrate proper gamma encoding. As in, the paintbrush (fer cryin' out loud!) still blends with the profile gamma rather than a linear gamma -- certainly by default. And scaling is really messed up. The least insane way to use Adobe products is with a gamma 1.0 working space and hope that quantization artifacts don't muddy your shadows. Again, great tools...but for something entirely different from colorimetry. b&
Chris Cox wrote:
This is very much incorrect, on assumptions and fact. Please see the documentation for DNG profiles, Camera Raw, and Photoshop.
Hi Chris, colorimetric photographic reproduction is something that Ben has pursued with some passion over the years, so if he says that DNG isn't so suitable for this type of use (backed up with various specific issues in regard to how Adobe products handle DNG profiles), then I'm inclined to believe him. Certainly the issues that Anders Torger has tripped across in developing his own DNG profilng solution (DCamProf) reenforce the view that there is some odd hard coded behavior in DNG. Cheers, Graeme Gill.
On Mar 14, 2016, at 6:08 PM, Graeme Gill <graeme2@argyllcms.com> wrote:
Certainly the issues that Anders Torger has tripped across in developing his own DNG profilng solution (DCamProf) reenforce the view that there is some odd hard coded behavior in DNG.
Anders has independently developed a very similar approach to mine, starting with a spectral model of the camera sensor. If you want the least-worst DNG profile you're going to get, you need to use DCamProf. And it's an open source labor of love with not much attention paid to user friendliness -- good results if you're willing to invest in the learning curve. But even at its best...you're still stuck with the bizarre illuminant nonsense that does this automatically-estimated blending between A and D50 with no meaningful user control nor input. Again, horses for courses. I can't imagine a _Sports_Illustrated_ or _National_Geographic_ photographer having any non-idle interest in my workflow. Lightroom and DNG is a great solution for those photographers -- and, indeed, for the overwhelming majority of photographers. You'd be hard pressed to better, even theoretically -- and anything you could do better in theory would have been impractical or impossible with the hardware on the market at the time it was developed. But just because Adobe products are excellent for most photographers doesn't mean that they're excellent for everybody. And, indeed, when it comes to colorimetric reproduction, they're no more suited to the job than Excel is to being a distributed relational database server. Cheers, b&
you're still stuck with the bizarre illuminant nonsense that does this automatically-estimated blending between A and D50
A and D65, not D50; and actually you can use pretty much any pair of illuminants; or even a fixed illuminant - exactly the same one you have in the studio. In my experience, most of the first-order colour and tone problems while going the DCP route come from the inability of a photographer to setup the shot of the target. The schemes are missing, the ready-to-go light setups are missing, flare, vignetting, uneven (in both SPD and evenness) illumination taking their toll. Several times I saw fingerprints and scratches on the target shots far beyond reasonable. -- Best regards, Iliah Borg LibRaw, LLC www.libraw.org www.rawdigger.com www.fastrawviewer.com
On Mar 15, 2016, at 9:20 AM, Iliah Borg <iliah.i.borg@gmail.com> wrote:
In my experience, most of the first-order colour and tone problems while going the DCP route come from the inability of a photographer to setup the shot of the target.
I can certainly believe that. And, of course, the same sloppiness inevitably carries over to the production shots. The marketing materials certainly don't help...they make it seem like all you have to do is hang a ColorChecker off your model's neck for one shot and you've magically got perfect color for the entire shoot. But, even if you start with a good capture of the chart...you're again limited (at least in practice, if not theory) to 24-patch original ColorChecker targets with no ability to supply custom measurements. And did you ever figure out how to keep ACR (etc.) from applying a contrast-enhancing S-shaped tone curve? When I was still wasting my time with it, I had to hand-craft an offsetting curve in the DNG profile editor -- and it was murder doing iterative approximations. Never could get better than sorta close. b&
I think the first need is to add diagnostics to profiler packages to warn of light/flare problems; and to stop pretending it is straightforward point and shoot solution. The procedures must be described and beta-tested; lighting/target kits must be tested and made available for the reasonable price; and all that for the market that generally not only does not use raw, but even if they do, ask "the camera set f/16, how the exposure could possibly be wrong?" -- the subject is a small dark bird, with the sky as a background ;) On Mar 15, 2016, at 12:29 PM, Ben Goren wrote:
On Mar 15, 2016, at 9:20 AM, Iliah Borg <iliah.i.borg@gmail.com> wrote:
In my experience, most of the first-order colour and tone problems while going the DCP route come from the inability of a photographer to setup the shot of the target.
I can certainly believe that. And, of course, the same sloppiness inevitably carries over to the production shots. The marketing materials certainly don't help...they make it seem like all you have to do is hang a ColorChecker off your model's neck for one shot and you've magically got perfect color for the entire shoot.
But, even if you start with a good capture of the chart...you're again limited (at least in practice, if not theory) to 24-patch original ColorChecker targets with no ability to supply custom measurements.
And did you ever figure out how to keep ACR (etc.) from applying a contrast-enhancing S-shaped tone curve? When I was still wasting my time with it, I had to hand-craft an offsetting curve in the DNG profile editor -- and it was murder doing iterative approximations. Never could get better than sorta close.
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-- Best regards, Iliah Borg LibRaw, LLC www.libraw.org www.rawdigger.com www.fastrawviewer.com
Hi, Chris. My objective is to obtain readouts using ACR’s eyedropper tool that display colorimetric accuracy. In other words, I need to create profiles for my camera + lighting combination so that an image I shoot of a target (let’s say the ColorChecker Passport) will display patches on screen with the same values they have in real life. What do you suggest I do in order to accomplish this in Photoshop and ACR (perhaps in Lightroom, too) ? Thank you.
On Mar 14, 2016, at 3:24 PM, Chris Cox <ccox@adobe.com> wrote:
Adobe products are all about "pleasing" color. Colorimetric accuracy is next to impossible using Adobe products -- and DNG profiles especially.
This is very much incorrect, on assumptions and fact. Please see the documentation for DNG profiles, Camera Raw, and Photoshop.
Chris
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Hello Joe: Here you have what I think you are looking for. http://people.csail.mit.edu/ericchan/dp/acr/ <http://people.csail.mit.edu/ericchan/dp/acr/> But you better take a look at this script. http://www.rags-int-inc.com/PhotoTechStuff/ColorCalibration/ <http://www.rags-int-inc.com/PhotoTechStuff/ColorCalibration/> I don’t know if it works on CC. Another one, ArgyllCMS based. http://www.jpereira.net/roughprofiler <http://www.jpereira.net/roughprofiler> But if you want to work with the light source of the scene, take a look to PictoColor. Thanks to Robin Myers include characterization of light sources with ColorCheckerSG and i1Pro. http://www.pictocolor.com/incamera.html <http://www.pictocolor.com/incamera.html> Only Rags Gardner’s script works directly in ACR. The other two generate a .icc Jose Bueno
El 15 mar 2016, a las 20:55, Joe <joemailgroups@gmail.com> escribió:
Hi, Chris.
My objective is to obtain readouts using ACR’s eyedropper tool that display colorimetric accuracy. In other words, I need to create profiles for my camera + lighting combination so that an image I shoot of a target (let’s say the ColorChecker Passport) will display patches on screen with the same values they have in real life.
What do you suggest I do in order to accomplish this in Photoshop and ACR (perhaps in Lightroom, too) ?
Thank you.
On Mar 14, 2016, at 3:24 PM, Chris Cox <ccox@adobe.com> wrote:
Adobe products are all about "pleasing" color. Colorimetric accuracy is next to impossible using Adobe products -- and DNG profiles especially.
This is very much incorrect, on assumptions and fact. Please see the documentation for DNG profiles, Camera Raw, and Photoshop.
Chris
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participants (6)
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Ben Goren
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Chris Cox
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Graeme Gill
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Iliah Borg
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Joe
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José Ángel Bueno García