I have been reading a lot about spectroscopy and spectral analysis lately. I got a lot of feedback from the community here and someone pointed me to how a Bayer webcam filter worked. The Bayer filter essentially is divided into 4 squares (or channels) per pixel - Red,Green, Green, Blue. For each pixel we get the four intensities (photon counts) from the webcam which will be reduced to three channels (RGGB -> RGB) by putting the two Gs together into 1 channel.
The Spectral Workbench shows us these three channels plus another curve for "average". And that's where I got stuck.
Why average?
If we want to know how many photons hit a webcam pixel at a certain wavelength - shouldn't we sum up the four (RGGB) or three (RGB) channels? We would get a much higher intensity curve that shows all photons. Averaging reduces the overall amount of photons per pixel.
Even the reduction of the two Greens into one channel by some "Bayering" arithmetics throws a lot of photons into the trash can. I've read that some people use CCD sensors with scratched-off filters to achieve better results but I guess it would need a change in the green channel averaging software, too, to receive more correct results counting all the photons available.
If I am wrong with my thoughts here it would be great if someone could explain to me where I was wrong.
In Spectral Workbench the Y-axis on the spectrogram is "Intensity (%)." If you took the sum of all three channels and plotted them on the same graph, wouldn't it look exactly the same as the average which is plotted now? There is no more information in the sum than in the average. Unless you are capturing and using camera RAW images, the data in the photo files have been through a lot of processing and are a long way from counts of photons. It's just some massaged representation of brightness.
Chris
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