Quote:
Originally Posted by Merlin66
For AP images can we call it "cosmetic noise" rather than refer to the scientific SNR - which is not really used......
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Some of us actually do the calculations to optimise data capture, so perhaps we can apply for a license to use the term SNR? Purely for scientific purposes, of course
Quote:
Originally Posted by Camelopardalis
Which poses an interesting question/curiosity from me...
How do you calculate the SNR of an image? PI gives an indicator of noise but not signal (unless I'm missing something obvious).
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Signal is what's in the pixels, Dunk
Take a look at the SubframeSelector script. It calculates a SNRWeight which gives you an idea of the quality of each sub wrt SNR. PI can only estimate noise, not measure it, so it's not perfectly accurate. High SNRWeight isn't always a good thing either. Light pollution reflected off a dirty big cloud will produce a high SNRWeight, and that's why we blink subs as well as measure them.
Don't forget that there's no such thing as a single SNR number for a sub. The SNR will be higher in bright areas and lower in dim areas due to the impact of shot noise.
Cheers,
Rick.