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Confused With Info Panel

Forum|Forum|8 years ago
June 24, 2017
2 replies
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I created a new Document in Gray Gamma 2.2

I filled the layer with RGB 128,128,128

Placing a target point on the gray layer, the Info Panel Reports

RGB 128,128,128

K: 43%

HSB: 0,0,50%

Plotting the point with a Curve, the Input value reads 145

Can anyone explain why the K: value is not 50% and why the Curve Input in not 128

Ian

info

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Correct answer D Fosse

Numerical values across color modes relate to your working spaces.

If you use gray gamma 2.2, you also need to set RGB values in a color space that actually uses gamma 2.2 - the only one is Adobe RGB. ProPhoto corresponds to gamma 1.8, and sRGB to sGray.

The dot gain grays have no RGB equivalent. They're supposed to compensate for ink spreading when it hits paper.

There is in fact no particular reason these numbers should match. They're not supposed to. If they do, it's mostly by accident.

D Fosse

Correct answer

Community Expert

Numerical values across color modes relate to your working spaces.

If you use gray gamma 2.2, you also need to set RGB values in a color space that actually uses gamma 2.2 - the only one is Adobe RGB. ProPhoto corresponds to gamma 1.8, and sRGB to sGray.

The dot gain grays have no RGB equivalent. They're supposed to compensate for ink spreading when it hits paper.

There is in fact no particular reason these numbers should match. They're not supposed to. If they do, it's mostly by accident.

davescm

Community Expert

Hi Dag

You are absolutely right (as I would expect from you on a colour issue ). I've changed the correct answer to yours.

The fact that I was using Adobe RGB as my color working space - caused the values I looked at to match .

However, I wonder why it has been implemented this way. Whilst of course the K value at 50% brightness, or "RGB" number will change according to the particular gray profile, it makes no real sense to have different values for the same pixel reported in the info panel , the histogram , the color picker and the curves dialogue.

I would have thought that on switching to a grayscale document profile - all the panels should switch to that common reference, including the color picker which should really only allow picking from gray when in grayscale mode.

Dave

davescm

Community Expert

Right. I actually thought that was the way it did work - that any open document should override the working space for that color mode. But I haven't checked this, and if not I agree with you.

Hi

It is a bit bizzare how the chosen colour working space in color settings affects the reported values in the panels for a document in a grayscale space.

Below are three examples, each created in Gray Gamma 2.2 and then filled with 50% gray. The only difference is that before each I changed the default working RGB color space.

Document Gray Gamma 2.2 ; Working Space RGB - sRGB IEC1966-2.1 ; Working Space Gray - Gray Gamma 2.2

info panel shows RGB 129, 129, 129 HSB 0%,0%,50% ; K50%

Histogram shows Mean value 128

Color Picker shows RGB 129,129,129 HSB 0%,0%,50% Lab 54,0,0

Curves 128

Document Gray Gamma 2.2 ; Working Space RGB - Adobe RGB1998 ; Working Space Gray - Gray Gamma 2.2

info panel shows RGB 128, 128, 128 HSB 0%,0%,50% ; K50%

Histogram shows Mean value 128

Color Picker shows RGB 128,128,128 HSB 0%,0%,50% Lab 54,0,0

Curves 128

Document Gray Gamma 2.2 ; Working Space RGB - ProPhoto; Working Space Gray - Gray Gamma 2.2

info panel shows RGB 109, 109, 109 HSB 0%,0%,43% ; K50%

Histogram shows Mean value 128

Color Picker shows RGB 109,109,109 HSB 0%,0%,43% Lab 54,0,0

Curves 128

So as the default RGB working space is changed (the document and gray default space always remaining the same) the reported values in the info panel and color panel are changing but the Histogram and curves are not. Something to bear in mind when looking at the values in the info panel.

Note this only applies to grayscale - when the document is RGB and in a different color space to the RGB default then the panels all align, as we would expect, to the current document space.

I checked this first in CC2017 then went and checked in CS6 to see if it had changed. the behaviour was exactly the same.

Dave