[mythtv-users] Monitor adustment with SMPTE bars/ was: color adjustment

Brian Wood beww at beww.org
Wed Jan 27 15:24:50 UTC 2010


On Tuesday 26 January 2010 10:28:54 pm David Brodbeck wrote:
> On Jan 26, 2010, at 8:39 PM, Devin Heitmueller wrote:
> > In terms of the your comments on the accuracy of the various formats,
> > I certainly agree.  However, I might argue that if the colors are
> > visibly off then even the color bars provided on DVD are probably good
> > enough.  It definitely won't give him studio quality, but would give
> > him something good enough for an untrained eye.
> 
> For home use, if it looks good enough, it is good enough. :)  (That
> was also my motto when I worked with CCTV surveillance camera setups.
> Although in that case it was more like, "if the gaming inspector says
> it's good enough, it's good enough.")

It's just as bad to make something better than it needs to be as to not make 
it good enough.

> 
> The sort of calibration procedure Brian described is meant to provide
> a reasonably consistent standard for a studio environment.  Actual
> color perception by the human eye is a lot less consistent.  Just
> changing the color of the wall around the TV set, or changing the
> lighting level in the room, will make the colors appear different to
> the eye. 

The worst case is trying to match multiple monitors, especially if they are 
being shot with a TV camera, which is a lot more sensitive to the various 
factors effecting color perception. For example, the human eye sees "white" as 
white under many differing conditions, including the color temperature of the 
light things are being viewed by. Nobody ever had to white balance their eyes.

The multiple monitor "Video Walls" that were popular long ago were a bear, 
getting 9 or even 16 monitors to match when "seen" by a TV camera is a bugger. 
We used either Barco CRT monitors or the Pioneer small projection units, both 
because they had minimal area around the picture, which would break up the 
"wall" effect.

An engineer once told em that if someone tried to sell him an optical 
instrument as bad as a human eye he would reject it. Upon reflection, he said 
that if all the builder had to work with was water and jelly perhaps the 
results weren't all that bad.

> Heck, I can sometimes detect a difference in color vision
> between my right eye and my left, and my glasses create "convergence
> problems" of their own, although with lenses it's called chromatic
> aberration.

I quit buying plastic lenses because of chromatic aberration, and went back to 
glass, problem solved, or at least greatly minimized.

> 
> I believe Netflix has the Avia home theater setup DVD.  That's
> potentially one way to get several test patterns, although last time I
> tried it the Myth internal DVD player choked on it.

Normally I'd not use anything recorded, but for most Myth users that's 
probably the best (or at least the only affordable) solution.


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