Brushing in Photoshop channel uses the colors chosen in the color mode picker, not channel selection

Forum|Forum|1 year ago
April 18, 2024
2 replies
396 views

I have an RGB image backed with a Spot color channel. With ONLY the spot channel viewed and selected, when I choose my colors (essentially 10% gray and 30% gray though chosen using RGB values) and paint using the brush tool, all is great.

Once I simultaneously view the the color channels, the color selector immediately changes to whatever was picked when the color channels were selected. Even if the RGB/Lab values match and I have the Spot channel selected, the brush paints darker (32% when viewing color VS 30% when not viewed.)

Is there a way to be able to view the color image and paint the colors selected when only the Spot channel is viewed? Is there a better way to select essentially gray values for the Spot channel? This may be a glitch in PS. I'm on Mac using the latest version of CS.

macOS

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D Fosse

Community Expert

It has to do with your working gray.

A single channel is represented in your working gray. Since this is essentially an untagged grayscale image, it takes on your working gray's tone response curve.

In full RGB display, the embedded RGB color profile takes over, and it has a different tone response curve. It you set a matching working gray it should be more consistent.

sRGB = sGray

Adobe RGB = Gray Gamma 2.2

ProPhoto RGB = Gray Gamma 1.8

Display P3 = sGray

D

David5E21Author

Participant

Thank you for your response. It did work! I'm still confused as why they designed it to work this way. I would think it would apply the same values to gray within the document regardless of viewing other channels or not. Anyway, solved! Thank you.

D Fosse

Community Expert

The basic problem is that they still use the outdated Dot Gain profiles as default working gray. The default today should be Gray Gamma 2.2 as the least common denominator. ACR does that.

The dot gain profiles don't match anything else and just cause a lot of problems. Dot gain means ink spread in paper, and a long time ago they were used as generic profiles for grayscale offset print. Today you use the K component in a standard CMYK profile.

Why the single channel representation is using the working gray is pretty straightforward. It's not an RGB image, so the document RGB profile simply cannot be used. It has to use a grayscale profile. So you set the one that has the same tone curve as your RGB profile, and they will match.

c.pfaffenbichler

Community Expert

When using B in HSB in the Coor picker the values seem to be laid down as intended (or rather 100-x).

Could you please post screenshots taken at View > 100% with the pertinent Panels (Toolbar, Layers, Channels, Info, Options Bar, …) visible to illustrate?

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