Re-Stacking Saved Frames

[poolemarkw]

Hello Everyone,

I was using SharpCap live stacking with an ZWO ASI178MC camera to capture M81 and the program crashed after about 600 frames. Fortunately I had "Save Individual Frames" turned on. Looking at them, I can clearly see faint representations of galaxy spirals. I've tried several times to use Deep Sky Stacker to re-stack the frames and results show no evidence of the spirals at all. I need some extremely detailed instructions regarding how to restack the frames (including my averaged Dark Frame). I'm also willing to use a different software program, whatever works!

Secondarily, are there plans to build a post-stacking capability in SharpCap? It seems very logical that if it can do live stacking that it should easily be able to do them after the capture process using the saved light and dark frames.

Thanks,

Mark

[turfpit]

Mark

These instructions have worked for me (sometimes) http://deepskystacker.free.fr/english/userguide.htm.

These days to process DSO captures, I use

• Nebulosity

• Autostakkert!3

Nebulosity http://www.stark-labs.com/ can be downloaded for free as a try before you buy and is fully functional except the final image is marked. Nebulosity does use a lot of disk space for the intermediate work files. The results (after the usual learning curve) have always been good for me.

AS!3 produces no additional intermediate files. I have used it to stack 1000 x 113Mb images which took about 40 minutes on a quad core Xeon with 16Gb RAM. Stacking was using Surface mode with a single reference point. https://www.astrobin.com/334986/?nc=user

How big are your 600 files? I could have a look at a subset if you can make them accessible. If you go this route, what is the debayer pattern for an ASI178MC?

Dave

[admin]

Hi Mark,

the latest versions of SharpCap (3.1) do their best to save your stack in all possible formats if the program crashes - they try to do that before showing the bug report option. Most of the time this should work, but sometimes the type of crash will prevent that from working sadly. Good to hear that you have the raw frames to work with.

SharpCap applies a default stretch to the image during live stacking (and you can enhance this) to help show the faint stuff. To see the faint stuff in DSS you need to apply a stretch manually by playing with the RGB/K level sliders and other controls.

There has already been a suggestion to have a type of 'camera' in the next version of SharpCap that will read files from a folder (either when they are dropped there by a capture program or work through them one-by-one) - this would allow the sort of trick you want to do of re-stacking the raw frames.

cheers,

Robin

[poolemarkw]

An Update...using AutoStakkert to open one of my saved frames I found that the bayer scheme is GRBG rather than RGGB that I had been using. Still, after debayering all of the images and my averaged dark frame using the correct debayering scheme, the resulting stack using DSS is almost completely washed out white. Any ideas?

[turfpit]

Mark

Can you make a subset of unprocessed light frames + the unprocessed dark available somewhere on the internet? Depending on the size, email attachments might work. PM me if you want to follow the email route.

Dave

[admin]

In DSS, you need to adjust the 3 sliders (circled) to place the peak of the histogram over the steeply rising bit of the rising curve, that usually deals with 'all washed out' and 'cant see anything at all' problems in DSS.

Capture.PNG (20.58 KiB) Viewed 2331 times

Were you saving RAW frames to FITS? FITS is a pain for Bayer patterns as some FITS reading software reads from the bottom up and some from the top down (AstroArt and PixInsight disagree on this). Because they treat different pixels as the start of the image, they need different bayer patterns - for instance for a particular image RGGB might be correct in PixInsight but GBRG would be required for AstroArt. This problem rather leaves me stuck as I can write out either of those as the bayer pattern in the file but not both

cheers,

Robin