I
found a link on identi.ca showing an awesome
plugin for GIMP. I thought I give it a try making textures for OpenArena.
When I want to make a seamless tiling texture from a photo I do the following: desaturize (getting rid of color changes), paint over the light and dark spots with a brush (getting rid of light changes), copy a wide part of the edge to the opposite site and use the clone tool or the smudge tool for seamless tiling and copy back the part where it belongs. It takes a long time, the resynthesizer plugin is much faster, but the result is different.
Here's the original picture I want to make a texture from. It's a pole not a flat surface, so it needs adjustments.
Here are the two textures. The manual processing took an hour, the resynthesizer took 1 minute and it still has the colors.
Here are the textures taken in game. Both are satisfying, but the resynthesizer is more patch like, the manual processing looks more like a unified surface.
The resynthesizer is much faster and probably can be improved with tweaking the parameters.