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
1 Correct answer
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.
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