Notes on processing of the M101 picture:
This image had bad Venetian Blind Effect problems even after applying the anti-VBE filter when doing the color synthesis in AstroArt. There was banding in the sky background with a width of about 3 pixels. As a quick and dirty way around this, I resampled to double the image size, translated by 3 pixels in Y and then averaged that with the original stacked luminance image. After resampling back down to the native resolution the resulting elongation of the stars was barely noticeable and the banding was almost completely gone. DDP and mild Gaussian filter followed by varios sharpening filters finished the job. In the reprocessed image I can set the contrast so that more of the galaxy is visible without getting an unacceptable level of banding in the background. Both versions are shown below for comparison: |
