Derive the plate scale (and error) of a FITS image that has a valid WCS in the header. If no WCS is present then the image type may be used. If not type is recognized then the output is "none none".

% image_ps --help 

Usage: image_20191018T024545.3_acm_sci.fits 
arg1 - FITS file image name
Additional options: 
     -v = print verbose comments 
 --help = view a help document 

% image_ps ../20191018T024545.3_acm_sci.fits 
0.27075139 0.00000126