converting floating point to RADIANCE HDR format

Thank you very much for the fast reply & comprehensive information!
I believe I have everything I need now ;-).



----- Original Message -----
From: "Gregory J. Ward" <>
Date: Tuesday, January 25, 2005 5:32 pm
Subject: Re: [Radiance-general] converting floating point to RADIANCE
HDR format

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
format is well-described in:

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

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

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


> From: Katja Doerschner <>
> 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
> 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?

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