Re: Change PCS of CLUT input profile
Re: Change PCS of CLUT input profile
- Subject: Re: Change PCS of CLUT input profile
- From: Mark <email@hidden>
- Date: Wed, 10 Oct 2007 19:42:29 +0200
Hello Graeme,
But of course it would help a lot to know WHY you want
to do such a thing ?
I want to apply an input profile to a live video stream. So far all
digital camera/scanner profiling packages I analyzed will generate
profiles with LAB PCS.
The "end product" shall be video in one of the many video standards
(Rec 709 or SDTV,... ). So I am thinking that for performance reasons
it might be smart to have the input profile directly output XYZ -
that makes me get rid of the LAB to XYZ conversion - that way I can
get from XYZ to any of those R'G'B's directly.
If any of what I am assuming is totally wrong - please let me know.
I've just started digging into color management...
Allow me to ask a somewhat related question: applying a CLUT profile
to live video is certainly computationally expensive - I'm planing to
do it on the GPU (OpenGL shaders). Shouldn't be so hard to do, I just
have to parse the profile and create the LUT-textures... and well,
do the math in the shader(s). I am looking for some code where I can
see what it really takes to apply a A2BX to an input XYZ (or LAB)
value. Can you give me a pointer where I might find such code in
argyllcms? That would be very helpful.
Using my toolset I could re-create the profile by making
a synthetic "chart" data set from the existing profile,
and then make one in the opposite PCS. You would loose
accuracy in the process.
I see, so the best would be to create the profile in XYZ right away
right?
Hum, I've lately been helping out the Lprof guys a bit to get a
working, well behaved, statically built Lprof for OS X. Maybe I can
persuade the Lprof guys to allow creation of XYZ CLUT profiles...:)
Best regards
Mark
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