Gamma settings in the Watec camera Version 19. January 2004
Martin Elsässer

Dark-images compared

The Watec WAT-120N has three different gamma settings: off, lo, hi. I took series of dark images with each of these settings, to document the effect of this setting.

The three images show dark-frames taken with the three settings. Each dark-frame is the median of a series of 35 indiviual images with the same settings.
The histograms of the dark images show the effect of the gamma setting: The curve is spread towards higher brightness values, with an amplification of low values .
Standard deviation of the pixels from the dark-images. For each pixel, the median brightness was established over the range of 35 images. All pixels with the same median-value were combined, to find the standard deviation. Generally, the lower the value, the less noise the system has.

The gamma values have a serious impact on the amount of noise, as the images themselves demonstrate. The usefullness of the higher gamma-values appears questionable.