Example output (plus a drop shadow effect):
Two other output examples (with normal map and probe image):
This plugin is compatible with GIMP 2.8 (and should be with any 2.x version I guess).
So far there is only a Windows precompiled binary: MLBevelReflect-win-2013-03-19.zip (176 KB)
Compiling yourself should not be hard on other platforms, it is a single .c file: source code on github
To install, just copy the binary in the gimp/plug-ins folder.
With an RGB or RGBA image with white foreground objects on a black background, call 'filters/Map/MLBevelReflect'.
For convenience: enable when you have an input image with black on white.
Flat is more like a 45 degree slope. The shape in the center is determined by the max. smoothing radius setting. You can use 1 pixel wide anti aliased foreground objects.
Round leads to a very smooth surface. Attention: Thick/wide objects currently take a very long time to compute!
Normal map encodes the normal direction in RGB as commonly used by other programs.
A spherical probe image can be used as an environment map. The top left pixel is used for the background of the resulting image. If you want to use the alpha channel, both the input image as well as the probe image must be in RGBA.
A diffuse reflection is an experimental option. At the moment it is probably better to manually blur the probe image yourself.
You can resize the dialog to resize the preview.
This plugin is free to use (released under the GPL). However, you might consider a donation, especially if you make money with it.