What is ISO on digital cameras?
by Volker Weber
Tony wants to call it gain. I think he is right.
Comments
Tony is overlooking just a small thing: sensor data are integer data of 8 to 16 bit range depending on camera and file format (raw mostly has more bits per channel). So, if you stretch the dark range too much to lighten the image, the "gaps" between the color values might become visible resulting in banding. With a raw file you might need to go to extremes but with jpeg this becomes visible fairly early.
(And most gif files, having only 255 discrete colors, show banding.)
Andreas Schleth, 2019-02-20
