[argyllcms] Re: Using I1Pro to calibrate an HDTV?
- From: Leonard Evens <len@xxxxxxxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 19 Jan 2010 23:42:51 -0600
On Wed, 2010-01-20 at 12:22 +1100, Graeme Gill wrote:
> 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.
Okay, things are beginning to come back to me now.
My Sony HDTV doesn't have genuine color management controls. But
there are controls which it seems to me I should try to set for photo
viewing, under the assumption that I have edited those photos so they
look more right than wrong on my color managed monitor.
I have the usual controls for brightness (black level), picture (white
level), color (saturation), and hue on a R to G scale. There is also a
color temperature control with four settings. Finally, there are
advanced controls, the exact meaning of which I shall have to
invvestigate, but one of them is another color balance control which
allows me, it seems, to set the color temperature in the highlights and
also in the shadows.
It seems to me that by understanding these controls and setting them
properly, I should be able to create images on my computer for viewing
on the TV which are acceptable. After all I have the advantage that
unless things are way out of line, the viewer's eye will adapt through
color constancy to see the image close to what is intended when viewed
on a screen in a darkened room.
>
> 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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