Re: Extracting green channel from FITS

Posted by han.k on Mar 07, 2022; 8:36am
URL: http://astroimagej.170.s1.nabble.com/Extracting-green-channel-from-FITS-tp1750p1852.html

Thanks Bill.

This confirms that for ASTAP all works correct. I'm sure Karen and Kevin will fix it in the next AstroImageJ

This time the signal is weak. Not a problem it confirms everything. The background pixel value is about 8300 there is some colour leak into the other Bayer pixels. The even and odd indication is in FITS coordinates.

BAYERPAT 'RGGB', image by ZWO ASIAir:

Original image, pixel values in the green area:
green ~15000   [even,odd pixels]
green ~15000   [odd even pixels]
blue   ~10000
red    ~10000

Original image, values in the red area
red ~10300   [odd, odd pixels]
other colours ~9000


Original image, values in the blue area    
blue  ~13000 [even,even pixels]
other colours, ~9600, ~8300 ~9700


Now the extract values in the 1/4 image:

ASTAP Green_TG  Green extract
green area 15074 (average)

ASTAP Red_TR extract
red area 10610 (average)

ASTAP Blue_TB extract
blue area 12864 (average)