I would like to compute the SH coefficients of HDR images and construct a sphere map of it.[/quote]

I've started my looking at the official project page, which contains the function [font=courier new,courier,monospace]prefilter.c.[/font]
The code structure is the following:

input(filename, width) ;
prefilter(width) ;
tomatrix() ;


Unfortunately though, when I tried running the c-file on HDR images, I got an error (incompatible format). The accepted format is .float. I would like to change the input(filename, width) function to accept the HDR format as well.
The next idea I came up with was to use a library to read HDR images, namely, the following.
Unfortunately though, this one is written in C++. Thus, I am asking myself how to combine the two.

Any ideas on how to get started would be greatly appreciated.