[argyllcms] B2A vs Inverse A2B?
- From: Jason Campbell <campbell.jj76@xxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Thu, 11 Aug 2011 14:05:28 -0400
I am new to Argyll and trying to understand something about one of the
behaviors in color lookups...
I have a profile built:
./colprof -v -qm -bm -kz -l400 -L0 -cpp -dpp testoutput
My goal is a CMY-only profile with absolutely no K generation which appears
to be happening. However I realized if I round-trip a CMY of 100/100/100
from CMY->Lab->CMY, I was getting a clipped value (roughly 98/97/95). If I
test CMY 50/40/40 my round-trip is extremely close to the input values.
Plots using:
./xicclu -v2 -g -fif -ia testoutput4.icc # Inverse A2B
./xicclu -v2 -g -fb -ia testoutput4.icc # Reverse; B2A (Actual lookup)
I could see apparent clipping in the plot. The Inverse A2B resulted in a
100/100/100 maximum CMY whereas the B2A lookup mimicked the clipping I
describe above. Do I need to alter the colprof command in some way to
create a B2A LUT without the apparent clipping? Is it related to the use of
the -cpp and -dpp switches?
I realize that I am essentially asking that the Inverse A2B and B2A end up
identical... Since I am using other tools in my testing, I need to access
only the B2A table (A2B not used in my application). I need Lab->CMY
lookups without the clipping I am observing up around 90%+.
Thanks in advance for any assistance!
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