Dear All,
I try to get most precise information from my ASI 290MM camera. However I got some troubles with pixel values manipulation. Hope you can help.
According to many sources, Unity Gain for it is 110, what means at 110 Gain 1 electron = 1 ADU.
Camera is 12 bit, so it have 4096 possible values for each pixel, however data are represented by 32 bit integers in range 0-65520.
Using SDK one can read following camera fixed informations:
ElectronsPerADU = 3.584
Offset_HighestDynamicRange = 10
Offset_UnityGain = 18
Gain_LowestReadNoise = 300
Offset_LowestReadNoise = 75
Notice: User can set "Brightness" (Offset). Even if set to 0 actually pixel value is always at least 16 (which correspond to sensor value = 1). For offset 1 and 2 average pixel value is still close to 16. Starting from offset value of 3 until 240, pixel value is equal (offset-1)*16 (with small variations of course).
result = (value+offset)*gain
OR
result = value*gain+offset ?
Notice: Even if image is highly saturated you will never get pixel value greater then 65504. Seems the real camera range is 1 - 4094 what correspond to pixel values 16 - 65504.
I found following could be an approximation:
PixelValue = Round( (TrueElectrons/ElectronsPerADU + Max(X+Offset;1) ) * 16
where X is between -0.5 and -0.85. The formula seems not to be good enough and I have no idea how to apply Gain.
Regards,
Gajowy
