id	summary	reporter	owner	description	type	status	priority	milestone	component	version	severity	resolution	keywords	cc
118	psImageReadSection supported datatypes.	robert.desonia@…	Paul Price	"I took a look at the SDRS when reviewing bug #103, and I found a bit of a
difference between the implementation I did and the description that I like to
bring up. 

I used 'fits_get_img_equivtype' to determine the most appropriate image datatype
for reading, which takes into account the bzero/bscale values.  Description of
this function from the CFITSIO manual is:

Th second routine [fits_get_imgequivtype] is similar [to fits_get_img_type],
except that if the image pixel values are scaled, with non-default values for
the BZERO and BSCALE keywords, then the routine will return the 'equivalent'
data type that is needed to store the scaled values. For example, if BITPIX = 16
and BSCALE = 0.1 then the equivalent data type is FLOAT_IMG. Similarly if BITPIX
= 16, BSCALE = 1, and BZERO = 32768, then the the pixel values span the range of
an unsigned short integer and the returned data type will be USHORT_IMG.  

This, I believe, is the best way to handle datatypes while the reading of FITS
files, as it opens up support for all non-complex datatypes that psLib supports
while allowing bzero/bscale to be handled (e.g., preserving the pixel values
properly).

The SDRS description ""This function will only read images of the native FITS
image types (psU8, psU16 (sic), psU32 (sic), psF32, psF64)"" is therefore not a
required limitation and I suggest it be removed.  

btw, the native FITS image types, sans bzero/bscale, are U8 (bitpix=8), S16
(bitpix=16), S32 (bitpix=32), F32 (bitpix=-32), and F64 (bitpix=-64).

-rdd"	defect	closed	high		PSLib SDRS	unspecified	normal	fixed