Hi Han, the updates to your program are working great on my Mac and I'm amazed at how quickly the program works. Thanks very much!
My ASI533MM Pro photos are 18.1Mb. When I use the Stack Menu to calibrate (only) my photos, the program returns a calibrated file marked ...cal.fit. The ...cal.fit file is 36.2Mb. However when I process a .fit file to calibrate and add AIRMASS through batch processing, the program does not change the name or size of the file. The FIT headers of both files show that they are calibrated and solved and include the AIRMASS information. What's the difference between the batch calibration process and the stacking menu process?
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Thanks for your help.
The single light or raw files are normally 16 bit. So each pixel is stored in 16 bit allowing grey level ranging from 0 to 65535. As soon you are calculating with the pixel values (applying flat, stacking & averaging) you will mathematically get values with a fraction. So if you stack two pixels having a value 100 and 101, the stack value will be (100+101)=100.5 For best quality you have to store these results in floating point values. This requires 32 bit so the file become double size.
Adding AIRMASS doesn't need to change the image data. Only the file header has to change. So the file can stay 16 bit per pixel.
process a .fit file to calibrate and add AIRMASS through batch processing
Calibration should create 32 bit files. Did it calibrate (See ckeyword CALSTAT in header) or only added the keyword AIRMASS?
Note next ASTAP version will have a major improvement in stacking quality.
Cheers, Han
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Hi Han, the updates to your program are working great on my Mac and I'm amazed at how quickly the program works. Thanks very much!
My ASI533MM Pro photos are 18.1Mb. When I use the Stack Menu to calibrate (only) my photos, the program returns a calibrated file marked ...cal.fit. The ...cal.fit file is 36.2Mb. However when I process a .fit file to calibrate and add AIRMASS through batch processing, the program does not change the name or size of the file. The FIT headers of both files show that they are calibrated and solved and include the AIRMASS information. What's the difference between the batch calibration process and the stacking menu process?
*
Thanks for your help.
The single light or raw files are normally 16 bit. So each pixel is stored in 16 bit allowing grey level ranging from 0 to 65535. As soon you are calculating with the pixel values (applying flat, stacking & averaging) you will mathematically get values with a fraction. So if you stack two pixels having a value 100 and 101, the stack value will be (100+101)=100.5 For best quality you have to store these results in floating point values. This requires 32 bit so the file become double size.
Adding AIRMASS doesn't need to change the image data. Only the file header has to change. So the file can stay 16 bit per pixel.
Calibration should create 32 bit files. Did it calibrate (See ckeyword CALSTAT in header) or only added the keyword AIRMASS?
Note next ASTAP version will have a major improvement in stacking quality.
Cheers, Han