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Taste AS
Taste AS
Participant
October 21, 2020
Answered

Neutral gray picked from background doesn't match in brightness and shows color shift when fixed

  • October 21, 2020
  • 2 replies
  • 564 views

Hi,

 

I use a gray layer (with a layer mask) in the color of the default Photoshop CC background to visualize my crop when I retouch.

 

Fig.1: However my eyedropper (set to point sample) samples a lighter color (or it appears so) when used on a Color Solid layer or just plain fill.

Fig.2 :When I shift the brightness to "match" with my eyes, the color shifts to a teal-ish color that is hard to see. Using hue/sat on top doesn't fix that.

 

It is visible on both my screens (Eizo CS2420 and my cheapo LG).

Working space is RGB ProPhoto RGB 16 bit and converting to 8 bit doesn't help. 

 

Any ideas?

 

Chees, Jacob.

This topic has been closed for replies.
Correct answer D Fosse

I was going to ask if you're working in ProPhoto, and then saw that you are indeed. Yes, I've seen this before.

 

This is a bug that affects ProPhoto files when you have GPU set to "Normal" or "Advanced" mode. Then the conversion into the monitor profile is executed in the GPU, and small inaccuracies somewhere in the code causes this. It only happens with ProPhoto because it is so large that these desaturated shadow values are extremely compressed. Tiny inaccuracies get amplified.

 

This bug has been around forever. It was first reported with CS5. It's probably not an Adobe bug, but rather in standard video driver rendering code somewhere. That's where it happens.

 

It does not happen in Adobe RGB, and it does not happen when GPU is set to "Basic", which shifts display color management back to the CPU in the traditional way.

 

Try to make a radial gradient with two dark neutrals, and see if you get this:

 

When you should be getting this:

2 replies

D Fosse
Community Expert
D FosseCommunity ExpertCorrect answer
Community Expert
October 21, 2020

I was going to ask if you're working in ProPhoto, and then saw that you are indeed. Yes, I've seen this before.

 

This is a bug that affects ProPhoto files when you have GPU set to "Normal" or "Advanced" mode. Then the conversion into the monitor profile is executed in the GPU, and small inaccuracies somewhere in the code causes this. It only happens with ProPhoto because it is so large that these desaturated shadow values are extremely compressed. Tiny inaccuracies get amplified.

 

This bug has been around forever. It was first reported with CS5. It's probably not an Adobe bug, but rather in standard video driver rendering code somewhere. That's where it happens.

 

It does not happen in Adobe RGB, and it does not happen when GPU is set to "Basic", which shifts display color management back to the CPU in the traditional way.

 

Try to make a radial gradient with two dark neutrals, and see if you get this:

 

When you should be getting this:

    Taste AS
    Taste ASAuthor
    Participant
    October 29, 2020

    Hi!

     

    Thanks for your reply, the color picker still doesn't do what I want it to (due to ProPhoto color space), however you have answered my long lived banding question, that I used to solve by adding grain.

     

    Changing the GPU mode worked great.

     

    Once again thank you for your quick response!

     

    Jacob

    Taste AS
    Taste ASAuthor
    Participant
    October 21, 2020

    I apologize for the typos (and the overlaying screenshots in Fig. 2), editing the post isn't possible for me.

     

    CheeRs, Jacob.

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