P: Black, White Gradient Preset and Perceptual Interpolation creates cool/blue cast

[J. Stuart Johnson]

Looks like one of the Gradient Preset: (Basics, Black, White [0,0,0 to 255,255,255]) is wonky when used as is. The grayscale ramp turns green when set to Perceptual Interpolation. However, the same present works correctly when using Linear and Classic interpolation. If I remake or simply edit the gradient, it works as expected. It's not my preferences, and color setting or at their defaults and I'm getting the same error on my laptop with a fresh install. I also noticed when I tried to edit the endpoint it came up specifying "Web Safe" colors which might explain the issue. But the simple act of editing it triggered it to work correctly and setting it back to "Web Safe" didn't recreate the error. Weird!

Anyone else see or able to reproduce this issue?

I'm using the latest Photoshop update on Windows 10 and Windows 11 on the laptop.

 

[AnthonyK]

I'm seeing the same thing.  Black-to-white "Perceptual" gradients have a greenish color cast compared to gradients made with the "Classic" gradient setting.  This is even more obvious if you use Filter > Blur > Average on the gradient and then invert it and keep going back and forth between inverted and not-inverted.   The "Perceptual" gradient alternates between a gray-green and redish-green color while the "Classic" gradient is a middle gray that barely changes when inverted.

[J453]

Thanks for the details. I have an inquiry out to the engineering team.

[DJM-LCS]

No update?  No fix?  This is just terrible.  Thought I was losing my mind with bad GPU or something, turns out it's another new, um, Adobe "feature."

[Mohit Goyal]

Hi all,

We're happy to announce the release of Photoshop 23.4. This update includes the fix for this issue. To see the list of all fixed issues, click here

To update Photoshop to 23.4, click "Update" in the Creative Cloud desktop app next to Photoshop. More detailed instructions for updating

Let us know if the update resolves the problem for those affected, and share your feedback.

Thanks,

Mohit

[AnthonyK]

I'm not seeing the change with 23.4.0.  These gradients were made with the Gradient tool on a 16-bit image with Adobe RGB as the color working space.  There's still an off-green cast to Percpetual gradient compared to the completely neutral Classic gradient.

[john kw62803249]

The "fix" in PS 23.4 did not work for me.  In fact, it still does not work in PS 23.5.3 nor in PS 24.0.1

The good news is that I believe I found the root cause issue.

Turns out the when using the default Black,White gradient there is not problem.

However, if one loads the Legacy Gradients and use the Legacy Black, White gradient the problem does occur.

The Legacy Black,White gradient has the Black Point set to RGB  0,0,2 instead of 0,0,0

In Perceptual mode this creates a slight green tone, in Classic mode there is a very slight blue tone, and very minimal shft in Linear mode.

The Legacy Black White Gradient in PS 2021 does not have this problem yet it does in PS 2022 and PS 2023.

When the Legacy Black, White Gradient has its Black Point set to 0,0,0 it works as expected in all modes.

For visualizing the problem I created a 256x256 pixel horizonatl gradient and extracted the RGB values for each postiion along the gradient and display them in a graph.

Following is the full graph of the Legacy Black, White Gradient in Perceptual mode:

Following is an enlarge view of the lower left corner of the plot where you can see the separation of the RGB colors giving the green tone.

Following is the same enlarge view using the Legacy Black, White gradient in Classic mode.  It has a slight separation as expected from the starting black value ot 0,0,2  :

Finally, here is the enlarged lower left corner of the Legacy Black,White gradient in Linear mode.  There is very little color shite yet it is still detectable when looking closely:

Hope this is helpful in the solution of the color tone problems with the gradient tool in PS 2022 and PS 2023

John Wheeler

[J453]

Legacy Presets are only compatible and made for use with "Classic" method. Use the shipping 'current' presets for use with Perceptual and Linear methods.

[john kw62803249]

Hi Jeffrey

I think you might have missed my points.

1) Helpx Adobe explicit shows how to load the Legacy Gradients to show first followed by the Default Gradients second. One can also rename the Legacy Gradient group name to whatever they want. There is nothing in PS that prevents one from using the legacy Gradients with any of the interpolation modes even if it is not supported. Those that are posting on this thread with problems may very well be using the Legacy Gradients with these new interpolation modes which definitely causes the color tone issues.

2) The Legacy Gradient "Black, White" does not work correctly even with the Classic Mode. As shown in my prior post, the RGB values are separated with blue dominating. I repeat the image here:

This separation can be totally eliminated by correcting the Black Point (which shows as 0,0,2) when Legacy Black, White gradient is used and is totally eliminated when and set back to 0,0,0.

The behavior of the Legacy Black, White gradient preset gives a different and color toned result in both PS 2022 and PS 2023 and not in PS 2021. In PS 2021 that preset the Black Point comes in at 0,0,0 as it has been in all prior PS versions.

I do plan on using the default gradients and delete the Legacy Gradients (even for Classic Mode) as I am not sure they would not be subject to similar issues.

Just thought it would be a reasonable explanation of why PS users are seeing problems with color tones with the Legacy Black, White gradient in all interpolation modes.

I would be happy to provide more details if desired.

[J453]

Thanks. Engineering is looking into updating the shipping Legacy Gradient presets.

[john kw62803249]

Hi Jeff

Just want to give you a heads up that the root of the problem may not be in just updating the Legacy Gradient files on PS 2022 and PS 2023.

On my Mac, the default and legacy gradients are stored in the Application Package and can be easily accessed.  I used Mac Terminal to compare the Legacy Gradient file with PS 2021 against the Legacy Gradient file in PS 2023 and they are byte for byte identical.  With PS 2021 there is not color tone in the Legacy Black, White gradient yet there is with the Legacy Black, White Gradient in PS 2022 and PS 2023.

That would tend to indicate that there is a difference in the computation path somehow.

Note that the PS 2023 default Black, White gradient does not have this problem.  That initially begged the question of why we don't see the problem in the PS 2023 defalut Black, White gradient.

I believe I have an explanation or at least a clue to that as well.

The gradient file stores the color mode/space of the gradient.  By examing the content of the gradient files of PS 2021 and PS2023 here is what I found for the color spaces in which they were created and saved. Note that I found it unusual that the saved color space for some of these files was in CMYK

PS 2021 Legacy Black, White gradient - CMYK

PS 2021 Default Blackm White gradient - CMYK

PS 2023 Legacy Black, White gradient - CMYK

PS 2023 Default Black, White gradient - Grayscale

Makes me wonder if PS 2022 and PS 2023 have a slight change in the conversion from CMYK to RGB compared to PS 2021 and prior versions.

Thought the extra info might be helpful with how to proceed.  Since the conversion from  Grayscale to RGB does not create the problem, it might be just updating the Color Mode of the Legacy Black, White gradient to Grayscale as well.

FYI

John Wheeler

[john kw62803249]

I dug into this issue more and achieved more clarity, which led to a solution. I also discovered that the problem is broader than the Black-to-White Legacy Gradient.

Photoshop Solid Color Objects (which includes Gradient Color Stops) can be any PS Color Model, e.g., RGB, HSB, Grayscale, CMYK, and LAB, independent of the Color Mode of any particular PS Document.

Within the Legacy Gradient Presets package, the Color Models I have seen used for the Color Stops include RGB, HSB, Grayscale, and CMYK. Some of the Color Stops within a given Gradient Preset use a different Color Model for various Color Stops.

From my examination, the initially reported color tint problem occurs because the Black to White Legacy Color Preset uses CMYK Color Stops with the Gradient Method "Perceptual" (and "Linear" to a lesser extent). The problems appear worse when a color channel of the Gradient approaches the low end of luminosity.

Note that the Gradient Methods of Perceptual, Linear, and Classic are only available on PS 2022 and beyond.

As it turns out, 47 or the 185 Legacy Gradient Presets also use CMYK Color Model in some of its Color Stops. Those 47 Presets with Color Stops in the dark areas do not convert well to RGB. Those Presets can demonstrate subtle yet unexpected hue, saturation, or luminosity shifts when using the Perceptual or Linear Gradient Method. Presets using RGB or HSB Color Stops do not exhibit problems.

I would be guessing to the exact reason that a CMYK stop sometimes causes these problems in the Perceptual/Linear Gradient Method and not in the Classic Method, yet I have found no problems for Gradients that only use RGB or HSB Color Stops. The solution is to convert all the CMYK Color Stops in the Legacy Gradient Presets to RGB.

I have done so for my use and no longer see any problems with Legacy Gradient Presets. I have exported that entire set of Legacy Gradient Presets and included a link to that file for anyone interested. Details on that link and file are below.

The regular Default Gradient Presets have no Color Stops using CMYK. So I suspect Adobe may have known about the issue of using CMYK Color Stops.

Also, the Black to White Default Gradient Preset used to be the only Default Gradient Preset with CMYK Color Stops. That Gradient also had problems fixed by changing the Color Stops to Grayscale and announced in one of the versions of PS 2022 and leveraged into PS 2023.

I have included two text files for completeness (and to shine a bit more light on the issue). One text file shows what Color Model was used for each Color Stop for every Preset in the Default Gradient Presets. The other file does the same for the present Legacy Gradient Presets.

I also explain why the Black to White Gradient Preset problem disappears when you open and do a sight edit on the black point Color Stop. The Color Stop takes on the Color Picker's Color Model. The Color Stop Color Model becomes RGB when changing the RGB number or slider. The Color Stop Color Model becomes HSB when changing the HSB number or slider. Neither the RGB nor HSB Color Models have the issue.

Given that the Color Model chosen for the Gradient Color Stop depends on what you do in the Color Picker, I recommend only using the RGB and HSB number/slider. I recommend only using the Lab text/sliders or the CMYK text in the Color Picker if you finalize the adjustment with the RGB/HSB text/sliders. That way, you end up with Color Stops in the safe RGB/HSB Color Models.

Here is the link to the replacement Legacy Gradient Preset file using only RGB and HSB Color Stops. To differentiate from the existing Legacy Presets, I have added a "JKW" suffix to all Gradient groups and a "JKW" suffix to any changed Gradient Preset. Two Presets have an added "Fixed JKW" suffix as those required modifications to the Color Stop numbers and the Color Model used.

Replacement Legacy Default Gradient Presets for upload via PS Gradient Panel 

Here is the link to the text file showing the Color Stop Color Models used for each Gradient in the existing Legacy Default Gradient Presets.

Color Stops for existing Legacy Default Gradient Presets 

Here is the link to the text file showing the Color Stop Color Models used for each Gradient in the replacement Legacy Default Gradient Presets.

Color Stops for Replacement Legacy Default Gradient Presets 

Here is the link to the text file showing the Color Stop Color models used for each Gradient in the existing Default Gradient Presets.

Color Stops for existing Default Gradient Presets 

I can provide upon request, examples of problems in the use of Gradient Presets with CMYK Color Stops

Always a possibility that even with care, changes in that many Presets could have an errorerrors. Let me know if any are found.

John Wheeler