On Mon, 31 May 2010 09:40:38 +0100, JTM wrote:
In article
. co.uk,
Dave Liquorice wrote:
On Sun, 30 May 2010 19:06:51 +0100, ARWadsworth wrote:

... the recordings were allowed to be used in court ...

What sort of technical specification is advisable? I
should imagine that a blurry, smeary, B&W shot of some
one, (who could be any body) only 1/4 height of the frame
has less chance of being of use versus a sharp, defined,
colour image even with the same sized figure.
Things have improved, but when cameras were fisrt used in
football grounds, the B/W pics were far better for ID
purposes than the colour. Colour was OK for, well, colour
of clothing, but for features and sharpness of image B?W was
best. (20 yrs ago FWIW)

It's still true today that webcams interpolate colour images
as they use a matrix of camera elememts, each sensitive to a
particular colour. They're usually grouped in 4's (2x2) so the
resolution for shapes is less than the number of pixels the
camera has.
The good news is that for some webcams, it's possible to reprogram
the firmware and get the "raw" pixel images, rather than the
interpolated, colour processed picture. Amateur astronomers have
developed some sophisticated techniques that will either allow you
to get native outputs as seen by the imager, (or will "brick" your
camera if you're unlucky, don't follow the precise instructions or
try it with the wrong camera, O/S or options). Do a quick google
for webcam and raw to see what's possible.
They also have written sofwtare that can "stack" images to improve
low-light sensitivity and do some neat image processing, too.