Re: 16 bit FITS image negative values misinterpreted

Posted by karenacollins on Apr 02, 2024; 8:57am
URL: http://astroimagej.170.s1.nabble.com/16-bit-FITS-image-negative-values-misinterpreted-tp2402p2403.html

Hi Cliff,

Integer fits files normally cover the range 0 to 64K. but get truncated at zero. When you say BZERO is set appropriately, does that mean it is set to 32768 (see below)? I assume BSCALE is either 1.0 or not present. If not, those could be the problem.

I tried downloading your linked image twice and it didn't finish either time. Even if it did finish, I'm not sure I am set up to decompress a "bz2" file. Could you please upload an example of a plain fits file?

Could you try opening your file in an alternate fits reader such as DS9 and see if you get the same result as AIJ? If so, then something is not getting written correctly from astropy.

Karen