Probable colormanagement bug in PL6

Photo-DKO · March 1, 2023, 9:17am

I know there an ongoing thread about colormanagement in PL6 but it’s very long and pretty much about figuring out what colormanagement in PL6 does, so I prefer to make a seperate post: IMHO there’s a bug in PL6’ colormanagement workflow. When we select the Classic (approx. Adobe98) Working Color Space colormanagement seems to be working as it’s supposed to (as far as dispaying on screen goes, not talking about exporting to DNG here, there’s also an CM issue with that). But when we select the new Wide Gamut option, CM only kicks in if we enable the Color Rendering module. This shouldn’t be. We shouldn’t be able to actually see any differences in saturation on-screen between both WCS’s, the benefit of a larger WCS being mostly smoother, more accurate gradients, whether we apply luminance curves or film sim’s (Color Rendering) or not.

This is also the case when in “compare” mode: the “no corrections” preview is not (correctly) colormanaged either.

FWIW…

Dirk

John-M · March 1, 2023, 9:52am

Assuming I’m understanding you correctly …

Not so. (With the “right” image; one with very saturated colours), the result of CM can be observed in both the image itself and its related histogram - by toggling Soft Proofing ON/OFF even with CR de-activated (and including with SP’s “Protect Saturated Colors” setting = zero).

I’m not sure if your wording (in italics) was intended to imply that something different occurs when the WCS setting is Classic/Legacy(?) … but, if so then that’s not so either; the result of CM being applied can be observed for both/either WCS setting.

platypus · March 1, 2023, 9:55am

Check out the “Protect Saturated Colors” slider. Depending on its position, it squeezes OOG colours into the gamut. There’s a whitepaper about it: DxO Wide Gamut - White Paper - DxO

Photo-DKO · March 1, 2023, 9:55am

Here are 3 screenshots that showcase the problem . I hope they will display accurately in this forum, I converted the screenshots to sRGB (they were grabbed from a Wide Gamut profiled monitor).

All images have no other processing enabled than indicated in PL6, these are Fujifilm raw files. Please observe the reds on the posts.

Classic Gamut WCS, color rendering off: the image on the right is correctly colormanaged.

Wide Gamut WCS, color rendering off, the image on the right should be colormanaged but isn’t:

Wide Gamut WCS, color rendering on (DxO Camera Profile applied), the image on the right is correctly colormanaged:

All three images on the left (the “no correction” previews are incorrectly colormanaged.

Joanna · March 1, 2023, 9:57am

I see no difference in any pf the images you have posted, using a P3 monitor.

Photo-DKO · March 1, 2023, 10:04am

Differences are VERY visible on all my screens (Wide Gamut main screen, sRGB secondary, and even on my smartphone, as well as on my less-than-sRGB laptop). Please observe the red plastic wrapped around the legs of that structure, at the bottom, specifically on the rightmost leg. It should be pretty obvious. Both in Firefox and Chrome.

You can also observe the yellow left side of the cabin.

Easiest method to observe the issue is clicking on the images to show them fullscreen and cycling through them using the arrows

John-M · March 1, 2023, 10:35am

Thanks for the visual direction - Yes, I can see that.

Do you have Soft Proofing enabled ? … 'cos there is a problem with the No Corrections reference image not reflecting the result of Soft Proofing (and thereby impacting the usefulness of “before/after” comparisons) - as @KeithRJ has previously reported / complained about as an issue.

Photo-DKO · March 1, 2023, 10:45am

With or without softproofing, the result is exactly the same, regardless of the profile I use to softproof.

MSmithy · March 1, 2023, 10:45am

I can see the difference in one image, in the yellow, yes. But I’m not quite sure what are we looking at exactly. What do these images represent? I’m unclear on that. Since you show no interface of the program I’m not sure where in the program these images are viewed.

The best I was able to see difference between DXO wide gamut and Classic (legacy) is when I switch between them the intensity slider in Color Rendering Tab changes. Resulting in differences in color.

Here is what I mean.

The User Manual for DXO says this.

Working Color Space

DxO PhotoLab (from version 6) uses an extended color workspace: DxO Wide Gamut, in addition to the Classic profile (Legacy), which matches the Adobe RGB 1998 profile, kept to prevent users from applying unwanted changes to images that they have already processed. The Colorimetric Space Subpalette lets you to manage images according to their color profile and convert them:

All images processed in versions prior to DxO PhotoLab 6 will use the Classic colorspace, but you can convert them to the DxO Wide Gamut space.

All new images opened in DxO PhotoLab 6 use the DxO Wide Gamut color space, for even richer colors.

Converting images processed in Adobe RGB to the DxO Wide Gamut profile may change some colors and so, depending on how the picture looks, you may need to redo some corrections.

Indeed, soft proofing is available for the DxO Wide Gamut space, as well as the Legacy colorspace.

Important

Since version 6 (October 2022), DxO PhotoLab is no longer constrained by the color space of the input image, as each one is converted to use the expansive DxO Wide Gamut color space. For most screens with restrained color spaces, out-of-range color warnings may appear in the Soft Proofing tool when correcting images. However, getting rid of these warnings should not be your aim as they do not concern the quality obtained in exported files or prints.

Since DxO PhotoLab 6.3 (February 2023), the DxO Wide Gamut color space applies to both RAW and RGB files (JPEG, TIFF, linear DNG).

A number of effects and renderings are not compatible with the DxO Wide Gamut working color space, and therefore are not visible in the relevant menus (left: Classic color space, right: DxO Wide Gamut color space):

ColorSpace_EN

Manual is here: General image corrections – PhotoLab Guidelines

Photo-DKO · March 1, 2023, 10:50am

Thanks you for taking the time to write this post. I’d rather not restart the same long thread on what colormanagement in PL6 does. I’m just reporting this bug. BTW These images are viewed in compare mode in the “customisation” (aka “development”) window. On the right side you have the regular “correction preview”. It’s indicated on top.

MSmithy · March 1, 2023, 10:52am

That’s fine, except I’m not sure its a bug to begin with.

I’m not sure I understand what the problem is. If you are comparing the same image only with different settings, how is that a bug?

Photo-DKO · March 1, 2023, 10:57am

There are no different settings. I just change WCS. That should not be visble except for more accurate gradients. As I said in my initial post, in Wide Gamut mode, CM kicks in only when the Color Rendering module is enabled. That is almost certainly a bug.

MSmithy · March 1, 2023, 11:04am

I think you are mixing something up here. Color Management seems to be as it should be. The appearance changes, because the settings change. Intensity slider is not a matter of color management, but of preference.

As for the differences in the way DXO behaves in different modes, I think that is indented to take advantage of the new Wide Gamut mode and classic as the name implies ( legacy) is left for backward compatibility.

I don’t see a bug needs fixing here, as much as your expectations need to be in line with the intended functionality of the tool. I have posted how things work, since you seem to be having a problem understanding it, and think its a bug. I disagree.

John-M · March 1, 2023, 11:38am

Dirk, I’m not clear on what you mean by “CM kicks in only when …” ?

i) What are you expecting it to do ?
ii) See my post above … based on what I’m assuming you mean, your assertion is not supported by practical observation.

What is correct is that the “Correction Preview” does NOT reflect Soft Proofing - - Is this perhaps what you mean (?)

Photo-DKO · March 1, 2023, 11:43am

I never mentioned any “intensity slider”. And sorry, I do understand colormanagement, I’m a 66 year old experienced editor and have studied CM over and over and over again. I use Lumariver, Argyll, ColorThink Pro and the X-RIte suite on a daily basis and print for exhibitions.

This being said, I will post some more obvious screenshots in a couple of minutes, it takes a while to make them (screenshots are not colomanaged so we need to assign the proper profile to the image and convert to sRGB for them to display as correctly as possible on othe random systems, and the I check before posting on several devices to make sure the problem shows.This takes a while.)

MSmithy · March 1, 2023, 11:54am

The intensity slider affects the appearance of the image while in DxO PhotoLab program. Its not part of color management per se anymore than soft proofing is. They are tools to adjust appearance of the image by user intervention and simulation.

It actually says so in the program itself if you click on the little “?” icon.

Color management in classic (legacy) mode as the manual says: Since version 6 (October 2022), DxO PhotoLab is no longer constrained by the color space of the input image, as each one is converted to use the expansive DxO Wide Gamut color space."

So when you use either classic or DXO Wide Gamut you are using color management feature, constrained to the DxO PhotoLab application. Once you adjust the appearance of the colors in the interface and you export your image you will have the ability to once again write a color profile in the image.

Color rendering is similar to other tools in the app, so you can adjust appearance of the image to your liking. Its not really a color management feature. It only acts that way if you use a particular profile that you load externally, like ICC or DCP profile, but regardless of that the intensity slider is for adjusting appearance…

As for difference between classic and wide gamut, I’ve explained that as well. So I’m not sure where the bug is?

As John stated “What is correct is that the “Correction Preview” does NOT reflect Soft Proofing - - Is this perhaps what you mean (?)”

Photo-DKO · March 1, 2023, 12:02pm

See my first post: changing WCS should not make any difference in rendering on-screen in a correctly colormanaged workflow. Expanding the WCS gives more precise gradients, but should not shift HSL. What I see, and report, is that when using WG WCS, the translation to output device colorspace (using the device profile) does not work UNTIL we switch on the Color Rendering Module. That is incorrect behaviour. When using Classic WCS (=Adobe98) the processing pipeline is correct.

I don’t talk about softproofing: it doesn’t make any difference using it or not.

Photo-DKO · March 1, 2023, 12:06pm

Please, I’m not talking about the “intensity slider” nor about softproofing.They are not part of the Color Management pipeline.

MSmithy · March 1, 2023, 12:08pm

Than what are you talking about , because you are not making much sense in your descriptions. Calm down, take a deep breath, and try again. What are you talking about, delicately? And please use terms that correspond to names of the features in the application.

I don’t understand what that means? What do you mean?. Can you explain in another way?

What “output device colorspace (using the device profile)” do you mean?

Egregius · March 1, 2023, 12:16pm

You are misunderstanding a few things. Color Rendering in an off state applies a different color rendering with the DxO Wide Gamut WCS than with Classic. This is for compatibility with older versions of PL. Off doesn’t mean a rendering isn’t being applied.

I have no idea what you mean by “color management” here. PL is an editor, it gives you what you ask for, not some objective right rendering of color.