Please help - SGPro fits file looks grainy

Sequence Generator
1

Hi, when I capture images with SGPro the preview on high stretch looks like the image below (really smooth)

However when I open them in Fitswork or AstroArt they look like this (really noisy)

I have applied a similar stretch to both (I think but I’m no expert!), I was hoping someone here might be able to explain why the fits file preview in SGPro is so much smoother than when viewed in Astroart.

Many Thanks

Alan

2

Alan, the SGP preview is just that. There are various methods of doing screen stretching. Maxim does a gamma curve and SGP changes the end points. I recall Fits liberator does the same. I would expect a single frame to be grainy in reality. The screen stretch in all these programs does not affect the image data itself.

3

Thanks Buzz, I understand that in SGPro it’s just a preview but it still looks really good and whatever I do I can’t match the quality in Astroart short of using denoise filters. Perhaps SGPro is doing more than just an endpoint stretch (like denoise) to create its preview? I love both programs, I was just worried that there may be some difference in the fits file format between them (like a different bit level or something)?

Thanks and Merry Christmas from Alan

PS I know I have a lot to learn so I really appreciate any help…

4

I found the solution I think, Fabio from Astro Art had an answer. The image I took is large and the preview was at a zoom level of 15% Astro Art does not anti-alias its preview by default which at that level of zoom causes a lot of noise. Once I turned on the anti-alias the image looked as smooth as it does in SGPro so I guess SGPro uses anti-aliasing on zoomed out previews.