Flat Screen Monitor As Light Source.. ?

It's not crazy, but it wouldn't work.

It turns out, even though you can control the color of a monitor very precisely, it would actually make a terrible light source. Ironically, better the quality of the monitor (in terms of gamut and color reproduction), the worse it would do as a light source.

The reason has to do with how we perceive color, and how monitors reproduce color.

Two objects might appear about the same color, but they might be reflecting entirely different spectra of light. For example, a yellow object might be yellow because it's reflecting yellow light. A second yellow object might be the same color to our eyes, but it might be reflecting both red and green light and very little yellow light.

A monitor is always going to be reproducing yellow by combining red and green light. That works fine, because our eyes see a combination of red and green as appearing yellow. In order to be able to reproduce the widest range of colors and the most saturated colors, monitors try to have very saturated subpixels, a very green green, very blue blue, etc. So each of the subpixels emits a fairly narrow spectra. The bluest blue is made by only producing light around a narrow wavelength and very little light from other parts of the spectrum that would only serve to dilute the blue color. The best, most expensive monitors (those with "wide gamuts") have subpixels with the narrowest spectra.

So when your monitor produces "white" it's not doing it the same way a traditional light source is. Its spectrum has three narrow spikes. Something like a traditional light bulb, or the sun is producing a broad, continuous spectrum that includes all the visible wavelengths. You could match the color of your monitor to a particular white light source very precisely, but the spectra is completely different.

So if you have those two yellow objects which appear the same color under daylight or under incandescent light, might look completely different when illuminated by a monitor. One might look fine, but the other will look pale and washed out. That's why people working in front of a computer look pale and sickly. It's not just because they never get any sun!

That's also why many fluorescent lights and LED lights might match the color of incandescent bulbs really well, but make the colors of things (e.g. skintones) appear strange. It's also part of why high quality photographic lamps and flashes are expensive; they need to be engineered to produce the same color precisely and reliably and different levels of brightness, but they also need to have a broad, continuous spectrum in order to produce accurate color with the objects they are illuminating.

The CCD is more broad-band so it can roughly emulate what the eye sees. In the example above, it needs to capture both yellow objects as yellow (one which reflects yellow light, and another that reflects a combination of red and green), so it needs to be sensitive to all wavelengths. A monitor doesn't need to produce yellow light at all to make the color yellow.

If you want a truly light spectrum equal light check out the luminescent panels I use in my astrophotography work. They are used for taking flats of very even light to help remove dust on the optics and light pollution or sky gradients.

http://www.gerdneumann.net/english/...verview.html

These are not the cheapest things and are fairly delicate, I've broken one already, the wires are too small of gauge and almost impossible to repair if pulled out. I use a 160mm and a custom made 18" panel for my various telescopes.