[argyllcms] Re: Eizo Internal LUT access with Argyll?
- From: Kai-Uwe Behrmann <ku.b@xxxxxx>
- To: ArgyllCMS <argyllcms@xxxxxxxxxxxxx>
- Date: Wed, 19 Oct 2011 08:44:58 +0200 (CEST)
Date: Tue, 18 Oct 2011 10:40:35 +0200
From: Sam Berry <samkberry@xxxxxxxxxxxxxx>
It's also worth noting that regardless of gradation precision, in-monitor
gamut transformation requires linearisation, which means that the monitor
must know the input tone curve. A calibration done with LUTs before this
stage means that any linearisation performed can only be an approximation.
The calibration will also need to be redone for each gamut transformation
selection.
It should also be noted that modern internal LUT monitors (inc Eizo now)
feature 3D LUTs which allow printer colour spaces to be emulated, and I am
not aware of any graphics card with similar features at this time. A well
There are a variety of dedicated device available performing just
real time colour conversions on a video signal at high resolution. I read
even of 3D tables with 256 grid size. A API for in computer colour
transforms is available through 3D texture lookups since OpenGL 1.x.
Thats guessedly the basis for full screen colour transformations in Quarz
Extreme and certainly in CompICC. Print simulation and other effects are
possible depending on the CMS'es customisation capabilities.
specified tone curve is essential for this emulation to be meaningful, and
once you have monitor communication too specify it, you may as well use
internal LUTs too.
The weak point with many in device colour conversions is the missed
communication link to the host computer. In PDF this is solved by
embeded ICC profiles in the print document. For video and desktop imagery
we have nothing like that. As a result we end in a inflexible situation
and lots of proprietary stuff involved, which is non productive and
completely contrary to tagging data with ICC profiles in a standardised
way. In the talk with a EIZO product manager, they offered a on screen UI
as a answere for a Linux API request. But thats not really helpful for
automated systems. Currently the best we can do is a 30-bit data path IMO.
kind regards
Kai-Uwe Behrmann
--
developing for colour management
www.behrmann.name + www.oyranos.org
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