16 bit FITS image negative values misinterpreted

Posted by clkotnik on Mar 30, 2024; 7:25pm
URL: http://astroimagej.170.s1.nabble.com/16-bit-FITS-image-negative-values-misinterpreted-tp2402.html

I have some images which, when calibrated, have some negative pixel values.  When these are displayed in AIJ, the ADU counts are very high instead of the expected low values as though the value is 64K plus the actual value.  These images have BITPIX=16 with BZERO and BSCALE set appropriately.  The astropy routines do the actual image generation.  The odd thing is that when the same image is simply converted to BITPIX=-32 with all the same pixel values, AIJ seems to work just fine showing negative values.

Is there a way to get AIJ to load the 16 bit images correctly?  Here is an example:
240323.bz2

thanks,
Cliff