[argyllcms] Re: Using I1Pro to calibrate an HDTV?
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Wed, 20 Jan 2010 12:22:57 +1100
Leonard Evens wrote:
available. I presume this won't damage the LCD screen, but I would like
confirmation of that.
However, it would be easier to use the I1 in `beamer' mode, which I
believe people here have discussed before. (Xrite sells a software
You can do things like point the instrument at the screen (and that
is a practical way of dealing with projectors), but the results are
going to be less good than treating it like a monitor and
using the appropriate LCD monitor adapter, because it will let much
less ambient light into the instrument.
Having calibrated the TV, I presume I can also build a profile which I
can use to modify images I put on DVDs for viewing, but I am unclear
about exactly how that would work. I've done something this for
printing, so I am sure I can reconstruct what I did, but some reminders
would be appreciated.
A lot of the time it's hard to apply the same approach used for monitors
to video playback, the reason being that the method of control of
the display is so different. Often video playback only has "user" oriented
controls like "contrast", "brightness", "color" etc., rather than
the sorts of detailed technical facilities needed for full
color management. If you're playing back through a computer then perhaps
you may find that the VideoLUTs are used, and calibration can be employed,
but often this is not the case, since the video playback may bypass the
usual rendering path (overlays etc.). I think also that you will find
that many (most ?) computer based video playback paths bypass any color
management, meaning that there is no opportunity to apply ICC profiles.
It is possible to color manage video playback if the correct rendering
path is used (ie. using the GPU to implement color management), but my
impression is that few if any consumer oriented systems do this,
and dedicated video playback equipment doesn't have detailed enough
controls to attempt proper color management (I think some high end
projectors may have VideoLUTs that can be accessed via proprietary
serial protocols, or even internal matrices or cLUTs, but such things
are very make/model dependent, and simply may not be accessible to mere
mortals.)
[The problem boils down to standards, or lack of them. If there was
a standard set of video color management features and a way of accessing
them, then calibration and profiling would be straightforward. But
this is not the case, and video manufacturers are all going their
own proprietary directions.]
Graeme Gill.
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