[cpia] CPiA 0.7.2 & Zoomtel camera: Colour balance strangeness

[Johannes Erdfelt]

On Tue, Feb 29, 2000, rich@annexia.org <rich@annexia.org> wrote:
> Dear all:
> 
> Running gqcam supplied with cpia-0.7.2 (kernel 2.3.48), or
> running Xawtv, I get strange colour-balance problems. The
> picture appears yellow most of the time, as in this example:
> 
> http://www.annexia.org/tmp/yellow.jpg
> 
> (about 1 in every 10 times I run the program, the colour
> is correct). Note that the walls in this picture are white
> and the poster on the right is turquoise.
> 
> If I put my hand over the camera for a few seconds, then
> afterwards, everything is green (:-) 
> 
> http://www.annexia.org/tmp/green.jpg
> 
> ... for a few seconds before going dark!
> 
> http://www.annexia.org/tmp/dark.jpg
> 
> ... permanently. You have to restart gqcam to get back to
> `normal' (ie. yellow mode).
> 
> I have tried setting color_balance_mode and exposure_mode
> to manual and auto, but to no apparent effect. I also tried
> setting the {red,green,blue}_gain settings, but these seem
> to have a mind of their own, and just wander back to obviously
> incorrect values after I set them (independent of whether the
> various exposure_mode and color_balance_mode are manual or
> not).
> 
> Oh, and these problems only really occur in low light conditions
> (with a 60W bulb). In very bright daylight the results are much
> better. Being a hacker I'm obviously mainly interested in the low
> light situation :-)

FWIW, I've seen this as well. It sometimes is yellowish, or purplish (I
think). Mostly yellow.

JE