Hi,
Browsing the LCMS code related to CIECAM02, I notice the "D value" used in
CIECAM02 chromatic adaptation is always calculated in cmsCIECAM02Init.
There's no option to simple set D = 1.0 and assume the viewer is fully
adapted. If you use the default viewing conditions and set La to 100.0, D
will be 0.94. If you set LA to 318.31, D will be 0,994. It's practically
1.0.
In the current implementation, you only can get a fully adapted viewing
condition with a high value for LA. IMHO, having a high LA, has impacts in
the "non linear compression". My question, is there any situation when you
need a fully adapted viewer and a low LA?
To solve this issue It would be easy to make a new function called something
like "cmsCIECAM02InitNoCA" (No Chromatic Adaptation) by modifying the by
changing the following line in cmsCIECAM02Init
lpMod -> D = computeD(lpMod);
to
lpMod -> D = 1.0;
I'm using CIECAM02 to profile a scanner, so assuming a viewer fully adapted
is very reasonable. I believe other applications would benefit with this
"new" function, but I'd like to understand better the correlation between
viewer chromatic adaptation and the non linear compression.
Best regards,
Lorenzo
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