RLE in HDR or PIC image files

Josh Code

I have been trying to make some software to generate high dynamic range image files(*.hdr) in the format specified by Radiance. The specs I looked at suggest the RLE for HDR is basically the same as for PIC.

It is described briefly here:
http://local.wasp.uwa.edu.au/~pbourke/dataformats/pic/

I have an uncompressed format that seems fine but I'm not sure how to do the Run length encoding. Uncompressed pixel data is done by using a 4-tuple to represent each pixel. red, green, blue, and an exponent byte.

What I've tried and failed at was a run length encoding where a byte precedes each pixel to indicate how many times the pixel colour repeats itself. This sometimes loads into PaintShop Pro and PhotoMatix but when it does, it doesn't look right at all. It shows a 90% black image with a few very bright dots in a grid pattern.

Do you know how the RLE works in HDR?

vpvp

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