Re: Panasonic Diffractive Color Filter/Splitter patent
Here\'s a simple toy mathematical model to demonstrate what happens with color errors.
Suppose we have a camera with 3 pixels, and light consisting of R+G+B photons is hitting each pixel.
The \"usual\" scheme is to use an R, G, or B filter on each of the three pixels. This directly gives the color signal one wants, with the usual counting statistics noise proportional to the square root of the number of photons for each channel:
R, dR = sqrt(R)
G, dG = sqrt(G)
B, dB = sqrt(B)
Now, suppose we instead use white, yellow, and cyan filters. Then, what we directly measure at the three pixels (with its counting statistics noise) is:
W = R+G+B, dW = sqrt(R+G+B)
Y = R+G, dY = sqrt(R+G)
C = G+B, dC = sqrt(G+B)
From this, we can un-tangle the colors to get back to R, G, B:
but now the color errors are about sqrt(5) to sqrt(6) times bigger (assuming roughly equal counts in each channel). We\'ve collected about 7/3 times as much light (so the luminance signal is much better), but the color noise is as bad as if we only had 1/5 the light compared to the R,G,B filter scenario!
Feb 04, 2013 at 03:20 PM
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