[vox-tech] Seeking Monitor Color Test program...

[Mike Simons]

On Thu, Feb 13, 2003 at 03:26:57PM -0800, Bill Kendrick wrote:
> On Thu, Feb 13, 2003 at 04:33:00PM -0500, msimons@moria.simons-clan.com wrote:
> > (basically a delay before screen changes of 1/4 of a second, and the 
> > ability to control how many pixels wide each rect is... defaulting to 
> > 1 pixel each, default to a fullscreen mode not window'd app, ability 
> > to pick the color range that is scrolled over so that it's possible 
> > to narrow down where the bad colors are, and the ability to print 
> > color number to stdout for start/end of page.)
> 
> It doesn't do exactly what you want at the moment, but it's a basic start:
> 
>   ftp://ftp.sonic.net/pub/users/nbs/unix/x/colortest/colortest-2003.02.13.tar.gz

  Very cool.  I modified that to do what I wanted, then sat here while
it cycled over all of the colors, then again with 4x4 boxes for each
color.  It doesn't look like a particular color is to blame... because 
I saw no flickering.

  The screen is 24 bit color on a Savage video card, with X 4.1.0.1
displaying to LCD panel over DVI cable.

  So, I hooked up a second monitor and see no problems.  I started messing 
with a copy of that debian-water.jpeg image which you used as a background
and really shows problems.  Below the word Debian, there is a large
field of wrong pixels, in the top right corner there is a small patch.
The monitor never shows pixel problems.

  I have found that several image viewing programs show weirdness on
this image until you zoom by more than a factor of 300%.  Once above 300%,
all bad pixels go away.  Also when zooming by 200% or so you can clearly
see the 'chunkyness' of the image but the bad pixels form small vertical
lines which are only one pixel wide.
  I discovered if I take a bad portion of the image zoom in about 200%
then scroll left and right there are some places no bad pixels will
show up.

  When using gimp if you turn off the green channel the bad pixels go
away completely... turning off both red and blue also make the bad
pixels go away.

  I think this is either a X Server bug or a video hardware bug
related to the combination of certain pixel colors near each other.

    I can show you all this stuff at the next demo,
      Mike