[argyllcms] Re: LCD TV
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Fri, 01 Aug 2008 13:31:42 +1000
Leonard Evens wrote:
Presumably I can do the calibration of the TV so that nothing is
uploaded to the video card and all color management is in the profile,
and then modify image files using the appropriate profile so they would
show up correctly on the TV. I believe I've done equivalent things
before, but I don't remember the details. Do I have it more or less
right?
In principle it's right, in practice it can be hard to achieve. You can't
calibrate, but you can profile, but how to profile is a problem. Typical
display measurement instruments measure one patch at a time, so you
have to present series of patches somehow, and synchronize the measurement
of them. It might be possible to setup some pre-determined patch sequence
on a DVD and then somehow figure out how to read them with an instrument,
but Argyll doesn't support this idea at the moment. If you had an instrument
that's capable of fast readings (e.g. and i1pro), it might be possible
to sample continuously and then automatically determine the patch boundaries,
but I'm not sure how that would work with an instrument that might take
up to 8 seconds per patch. The practical approach becomes having an IR
(Infra Red remote) output on the computer, and using it to advance the DVD
patch by patch under computer control. I'd imagine there are some color
management systems that support this; commercial or maybe the HCFR project.
The IR driver needs to somehow know the codes of popular DVD players of course,
or have some way of recording and playing back such a code.
Of course in theory a TV system should be operating in a standard color
space (ie. NTSC), although it wouldn't surprise me if the accuracy with
which they conform to such standards is low, especially when each manufacturer
is striving to stand out in the marketplace.
Graeme Gill.
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