Hi! I'm hoping someone can help me with this image of the Eastern Veil. When I open and look at it with ASTAP, the bright star (52 Cygni) has a large hole in it. This file is 8 hours of stacked images using DSS. If I open up an individual frame with ASTAP, everything looks fine. Some other stars also have this issue but the most obvious one is the brightest star. Is there a setting in ASTAP that can fix it? Thanks!
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Looking to the image, the pixel values at the bright star turn negative. Somehow a value is exceeding it's range and end up in a negative area. That is difficult to understand since all pixel manipulations are done using floating-point arithmetic.
The trace the problem, I need the two original images. With those I can analyse the process in the debugger. I suspect it has something to do with the format of the two original files. Can you attach in a post at the ASTAP forum or share them in an other way? First thing to try is to save the original files a 32 bit integers and not as 32 bit rational.
Han
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The problem is in the 32 bit integer file. The 32 bit rational files are a normal FITS file in float format showing now black hole.
Yes, I can download these files.
The DSS file in 32 bit /ch-rational looks normal. The FITS header indicates a -32 type which is a normal FITS format for 32 bit floating point values. The range of the values is 0..1.
ASTAP reads and display this "32 bit /ch-rational" as normal.So I would just continue with it and avoid the other type. ASTAP will display/convert the 0..1 range as 0.65535 but that doesn't matter.
The histogram shows different levels for red, green and blue. Red is the weakest. You can fix that before or after the mosaic by tab Pixel math 1, Colour correction. Hit Auto, hit Apply.
Han
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[https://drive.google.com/file/d/1VJvMIAEo1sxACneBtBD1DUNSfnusi65a/view?usp=sharing]
Hi! I'm hoping someone can help me with this image of the Eastern Veil. When I open and look at it with ASTAP, the bright star (52 Cygni) has a large hole in it. This file is 8 hours of stacked images using DSS. If I open up an individual frame with ASTAP, everything looks fine. Some other stars also have this issue but the most obvious one is the brightest star. Is there a setting in ASTAP that can fix it? Thanks!
Hello Justin,
Looking to the image, the pixel values at the bright star turn negative. Somehow a value is exceeding it's range and end up in a negative area. That is difficult to understand since all pixel manipulations are done using floating-point arithmetic.
The trace the problem, I need the two original images. With those I can analyse the process in the debugger. I suspect it has something to do with the format of the two original files. Can you attach in a post at the ASTAP forum or share them in an other way? First thing to try is to save the original files a 32 bit integers and not as 32 bit rational.
Han
This is an issue with DSS: https://groups.io/g/DeepSkyStacker/topic/dark_centers_to_blown_stars/92819060?p=,,,20,0,0,0::recentpostdate/sticky,,,20,2,0,92819060,previd%3D1660121395738625378,nextid%3D1654542391307056575&previd=1660121395738625378&nextid=1654542391307056575
Hi Just, Hi Klaus,
I have received the files via
https://www.cloudynights.com/topic/835873-astap-mosaic-created-holes-in-some-stars/#entry12075436
The problem is in the 32 bit integer file. The 32 bit rational files are a normal FITS file in float format showing now black hole.
Yes, I can download these files.
The DSS file in 32 bit /ch-rational looks normal. The FITS header indicates a -32 type which is a normal FITS format for 32 bit floating point values. The range of the values is 0..1.
ASTAP reads and display this "32 bit /ch-rational" as normal.So I would just continue with it and avoid the other type. ASTAP will display/convert the 0..1 range as 0.65535 but that doesn't matter.
The histogram shows different levels for red, green and blue. Red is the weakest. You can fix that before or after the mosaic by tab Pixel math 1, Colour correction. Hit Auto, hit Apply.
Han