[fitsbits] Re: Reading floating point FITS files

[Thierry Forveille]

John Green writes:
 > I don't face any problem reading 32 bits per pixel files for example
 > because it is a standard color depth, any developer involved in
 > imaging knows exactly how to deal with it ( just read the 4 bytes,
 > extract the 3 bytes related to color: R,G,B and feed them into the
 > bitmap )
 > 
If you do that with a 32 bit/pixel FITS image you'll get a display, but
definitely not a meaningful one ;-) Integer FITS data are actually fixed
point numbers, not integers. The physical value is obtained by
float=BZERO+BSCALE*integer


 > But a -32 bit (32 bit floating point) color depth is something I have
 > never heard of. Simply I don't know how to extract the 3 color bytes
 > (R,G,B) from the floating point data.
 > 
 > To cut it short: I have just one specific problem: how to extract
 > R,G,B data from the -32 bits per pixel FITS images.
 >
Please read again what has been said to you, and try to understand it. 
To cut it short: FITS IMAGES DO NOT CONTAIN RGB DATA in any hypothesis-free
form.