Quote:
Originally Posted by Bassnut
Marcus, loading into PS unstreched with a low count ADU medium stack needs so much stretching that "combing" artifacts appear (spiky histogram) due to just a few (can be less than 8 bits) A/D levels becoming visible.
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Waa???
Too techno for me. If you mean that stretching low S/N data yields a noisy result (= spiky histogram) well OK.
Quote:
Originally Posted by Bassnut
I like moving FITS into PS via fits liberator because it has very tweakable strectch algorithms. Unfortunately it cant handle RGB FITs, so the only way is to save RGB in CCD stack as TIFFs and directly into PS. I had trouble with colour create balances with mono subs in PS so tried colour create 1st in CCD stack, which is easy. Unfortunately the scale function in CCD stack clips (it maybe ive done something wrong, but I cant see it), its now back to seperate mono FITs.
If you are importing unstreched Lum, then you must have good data. 3nm Ha especially can be dense, but low ADU count.
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I didn't think loading FITS RGB channels one at a time into PS from the same low S/N data would be noticeably better (??) I imagine you could also disrupt the colour balance you achieved in CCDStack thus making your PS exerience more challenging. Re the clipping, I'd suggest not doing any DDP or trying to adjust the gamma in CCDStack - much more control over these things in PS. I only do initial colour combination in CCDStack and save unscaled.
I import my LUM as FITS (logarithmic) into PS. Same with Ha but yes, I use a 10nm filter and my subs are usually 30 mins at the longer FL. I generally apply 2 to 4 stretching curves layers (depending on signal level). I then apply noise reduction to a masked copy of the unstretched layer. For my RGB I may apply more stretching layers and sometimes do noise reduction the same way. I typically also blur it a bit (but not always). Layer masking is a must of course.
Cheers, Marcus