IR and QC

Gary Melander (garym@onramp.net)
Thu, 15 Aug 1996 13:11:05 -0500 (CDT)


I've been following the discussion on IR vision with the Quick Cam. I will
reiterate my findings here in case anyone can find use of them.

The QC (at least, MY QC) is especially sensitive to NEAR-infrared light, Not
infrared. In other words, optimum sensitivity appears to be in the near-IR
region, around 900 to 1150 Nanometers. This isn't suprising, since this is
the hot bandwidth of an ordinary PiN phototransistor. CCD's are basically
arrays of phototransistors, so it makes sense. And no, the QC can't detect
body heat, unless, of course, your body temperature rises to the point of
incandescence.

Nearly ANY color of monochromatic filter plastic will increase sharpness.
This is due to the black and white CCD's optical characteristics. If you can
live with the luminance losses, you can attach this inexpensive material
right over the face of the cam. The best red filter I have found is for red
HeNe laser applications. (632 Nm, or "Middle red") I get incredible
sharpness, but contrast needs to be adjusted in the cam's setup. White
balance and brightness will also have to be tweaked, but far less than the
contrast.

Here is an experiment for the techies out there:

Grab a red, blue and green filter from Edmonds Sientific or some photoshop.

Snap 3 identical pictures through each of the 3 filters.

Using Picture Publisher or any other decent art software, combine the RGB
data from all 3 pictures, which will yield a COLOR pic with higher quality
than that of the Color version of the QC.

We've been doing this on satellites forever.... In fact, this is how the
Hubble Space Telescope takes color pictures. The camera itself is a super
high resolution Black and White CCD. An array of mechanically actuated
filters are moved in and out of place in the boresight of the telescope,
depending on the spectrum of the subject they are viewing.

As for using the QC for motion detection, its just a question of comparing
sequential frames of image data.

I hope this helps.

Gary Melander
Binary Farm

"Catnip" on http://rampages.onramp.net/~garym