[Radiance-general] converting floating point to RADIANCE HDR format

[Gregory J. Ward]

Hi Katja,

Why don't you just borrow the OpenSource C code in the Radiance 
distribution?  No need to roll your own, really.  The Radiance picture 
format is well-described in:

	http://radsite.lbl.gov/radiance/refer/filefmts.pdf

The code you want is in the ray/src/common directory in the 
distribution, which may be downloaded from:

	http://www.radiance-online.org/software
or:
	http://radsite.lbl.gov/radiance/download.html

There is also a program that will convert from floating-point raw files 
to and from Radiance pictures, called pvalue.  It's use is a little 
obscure, though.  It's described in the man pages section on radsite:

	http://radsite.lbl.gov/radiance/man_html/whatis.html

I assume you read the article in Graphics Gems II, already?

-Greg

> From: Katja Doerschner <kd462 at nyu.edu>
> Date: January 25, 2005 2:07:28 PM PST
>
> Hi,
>  I have an array of M x N x 3 (as in RGB) single precision floating
> point numbers,
>  and would like to save it as a RADIANCE hdr format which uses 32 bits
> per pixel,
>  i.e. R G B have each 8 bits and they all share one exponent which is
> also 8 bits.( If I understand this correctly)
>  I would like to know how exactly the format works. How does one pick
> the common exponent? How does one deal with extrem intensity values in
> the different color channels?
> I am writing the program in C.
>  Can anyone help?
>
> THANKS