Re: SNR calcs

Posted by karenacollins on Jul 04, 2023; 10:36am
URL: http://astroimagej.170.s1.nabble.com/SNR-calcs-tp2244p2259.html

Hi Beka,

It looks like the 32 bit image has been normalized. When the calibration/image processing software changes the overall scaling of the image, it is effectively changing the gain. For instance, if your initial image values ranged from 0 to 65K, and the calibrated image ranges from 0 to 1, then the gain has changed by a factor of 64K! So, you'll need either have your image processing software NOT normalize the image values, or you'll need to know the normalization factor and include that factor in the gain setting in AIJ (multiplied by the actual detector gain). That will scale the pixels values back up for purposes of calculating SNR.

Karen