Slight change in gray scale values after an ICC profile conversion when using babl color transforms
@ellestone
Submitted by Elle Stone Link to original bug (#795178)
Description
Created attachment 370824 screenshots of using vs disabling the babl color transforms
This is an obscure bug, but here goes:
- Start GIMP with the babl color transforms disabled using these lines in a "start GIMP" script:
GIMP_COLOR_TRANSFORM_DISABLE_BABL=yes export GIMP_COLOR_TRANSFORM_DISABLE_BABL
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Make a 32f linear precision solid white image. Color pick to confirm that the "Pixel" readout is R=G=B=1.000000.
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Change the precision to "Perceptual" and then do an ICC profile conversion to my "V4" linear gamma sRGB profile from disk - sRGB-elle-V4-g10.icc
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Color pick again, and the "Pixel" readout is still R=G=B=1.000000, as expected, given that the XYZ values in the built-in GIMP sRGB profiles are an exact match to my "on disk" sRGB profiles.
Now close GIMP, comment out the two "DISABLE_BABL" lines in the "start GIMP" script, restart GIMP, and repeat as above. This time, after step 4, the "Pixel" readout is R=G=B=0.999985
I noticed this peculiarity while trying to check how default GIMP handles drawing a gradient on a mask since the latest changes in how layer masks are handled. This is repeatable at will.
Attachment 370824, "screenshots of using vs disabling the babl color transforms":
Version: 2.10.0-RC1