Loading FITS and TIFF Files

General discussion about StarTools.

Loading FITS and TIFF Files

Postby Jonesdee » Thu Dec 07, 2017 12:26 am

Hi, I am relatively new to Astro Photography and a new, trial user of StarTools.

After trying DSS, a Pixinsight Trial and AstroPixelProcessor for stacking images I have chosen APP as my preferred stacking software. To date I have been post-processing (non-linear) in Photoshop with encouraging results, however StarTools looks like a good alternative, hence I have downloaded the trial software for evaluation.

I suspect that it is probably a failure on my part, but I am unable to get FITS or TIFF images generated by APP to open in StarTools. The FITS files appear to be opening, but eventually StarTools reports that it is not responding (after a number of minutes). TIFFs fail immediately with a 'Failed!' error message. Both file types open OK in GIMP2 and Photoshop respectively. TIFF files from APP which have been opened in Photoshop and re-saved will open OK in StarTools.

Is there a file size limit for StarTools, or possibly an issue with the APP file formats? I initially suspected that the long filenames generated by APP may have been the issue, but truncating these to a short name makes no difference.

As mentioned above I may be overlooking something obvious, my apologies if this is the case, however any advice to get me up and running would be appreciated.

Thanks and regards

Dave
Jonesdee
 
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Re: Loading FITS and TIFF Files

Postby admin » Thu Dec 07, 2017 12:50 am

One occasion when FITS files may take longer to load, is when a file contains large swathes of "NaN" pixel entries or entries that lie beyond what is specified as the maximum and minimum values for the dataset. These entries signify a lack of recorded information at those pixel coordinates.

The (sometime long) pause is caused by StarTools attempting to fill in this information with educated guesses, so that it is possible to use most algorithms in StarTools that rely on 'valid' data across the whole image. Without 'valid' data, some algorithms otherwise may produce artifacts in places (not just in StarTools but in other programs as well).

To avoid this altogether, try stacking in a way that ensures the final result is an intersection of all frames, meaning that the result contains only pixels that have valid data in all frames.

Do let me know if this solves you problem,
Ivo Jager
StarTools creator and astronomy enthusiast
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Re: Loading FITS and TIFF Files

Postby Jonesdee » Thu Dec 07, 2017 8:00 am

Good morning Ivo

Many thanks for your prompt reply!

I suspect that one image that I have tried to load would certainly fall into the category you described - the target was M1, taken over several nights without paying particular attention to the rotational angle of the camera. The uncropped, stacked image has sections with no recorded image data where the stacking process rotated the frames to align the target correctly. I believe that APP allows cropping as part of the stacking process - something I have not tried, but will do so tonight and report back.

I will also check other stacks that did not load for similar issues.

In future I will be sure to use the mask feature of BYEOS to align image frames taken on different nights.

Kind regards

Dave
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Re: Loading FITS and TIFF Files

Postby Jonesdee » Thu Dec 07, 2017 7:50 pm

Hi Ivo

Cropping the image has solved the file loading issue. I have just tried a quick run through your recommended work flow and am very impressed with the result of my first attempt (I can show you a copy once i have purchased a license :) )

Thanks again for your help

Regards

Dave
Jonesdee
 
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Joined: Wed Dec 06, 2017 9:59 pm


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