10 replies to this topic

[MarMax]

I must have changed a setting in SharpCap without knowing it. The PNG saved with adjustments does not have the dark rings but the FITS file does. This is a screen grab of the FITS file opened in Astro Pixel Processor.

 

IC 342 screen grab

 

 

This is with the 533MM and taken about a week ago. I just now got around to looking at the 32-bit FITS stack and was surprised to see the dark rings.

 

What setting did I mess up this time?

[Jim Waters]

IMO looks like the pixels are saturated.  Need others to jump in.

[Clouzot]

Apart from the Preprocessing / Mask overexposed pixels setting (which shouldn't apply to individual saved FITS anyway), or the odd bug in SC, I don't see anything. Does that happen with other software (Siril, ASTAP etc) when you open the same file?

[RodgerDodger008]

Never seen anything like that before, mismatched darks maybe, there are some stars of similar brightness without the artifacts which seems strange. If the saved as seen does not have this atrifact I would say it is software related maybe but that is a super wild guess. Open the same image in GIMP and see if the same artifacts show up.

[DirtyRod]

I’ve seen it but only after a processing issue. What “adjustments” did you make?

[fullthrottle_man]

That picture looks like the results I get when I turn on the Hot Pixel Remover feature in SharpCap...

[alphatripleplus]

That picture looks like the results I get when I turn on the Hot Pixel Remover feature in SharpCap...

Yes, I believe it happens if you select cold pixel removal as well as hot pixel removal. I remember seeing this only when I used cold pixel removal; no black cores for me if I only select hot pixel removal. At least that was my experience last time I messed with cold pixel removal a few months ago.

[Borodog]

Report this to Robin, please.

[amitshesh]

Over sharpening or aggressive noise reduction would be my guess.

[MarMax]

Thanks for all the replies. What I posted is straight out of SharpCap saved as a 32-bit FITS. Flat(dark) and dark applied with non-linear gradient removal and satellite removal. I did nothing with it other than open in APP, zoom in, and take a screen grab. And any histogram settings should not matter since it's the 32-bit FITS.

 

I'll post it up on the SC Forum when I get back home from Darwin.

[amitshesh]

by sheer coincidence last night I was processing my subs in Siril. When I was using its noise reduction algorithm and tried some aggressive settings, it produced these black spots on my stars. So my money is some kind of noise reduction or sharpening.

 

Mathematically these spots seem to be due to some overflow for overly large values, or values becoming negative causing this discrepancy in drawing it.