Re: Of video resolution, Q-Cam and video-grabber boards

Alan Larson (larson@net.com)
Fri, 29 Dec 95 10:41:29 PST


> I also noticed the same when receiving images from Mac's which
> were using a digitizer and a camera. The picture were always
> much sharper than Q-Cam windows which displayed at the same
> time. The Q-Cam 16-64 Gray adjustment does not seems to make
> any difference in tests done on a target test pattern.
>
> As anyone notice this difference? Why? The image are always
> 120x160, the camera CCD resolution is in each case higher than
> CU image, therefore not the limiting factor... What is happening ?

Well, this is an example to show that there is more to quality
video than resolution.

The luminance dynamic range of the quickcam is fairly poor when
compared to the more expensive cameras. The lens is much poorer,
and the difference is visible in geometric distortion, as well as
other artifacts.

The varying brightness as the exposure interval occurs during
different brightness levels under flourescent lights. Better cameras
have more stable outputs.

The sensitivity to different colors of light is not as well balanced
as the better cameras (particularly the color ones), so the image
doesn't look right in that respect.

The same thing is true of television cameras -- you can have a
400 line resolution color camcorder that does a great job, but
it still is far below the performance of a $20,000 pro camera.

Alan