GIMP Script: Tile Shuffle
Over in Woekan’s Dungeon Tiles in Adobe Photoshop Tutorial I mentioned doing this with gimp, and referenced a script I wrote to shuffle tiles.
When run, the script prompts for X and Y tile size. The default is 100 for both.
Here is a sample source:
If the width or height aren't evenly divisible by the tile size, then the strip of partial tiles on the right and/or the bottom are shuffled. If both aren't divisible the lower right part tile will not get moved. (This is shown in the previous example.)
Now where this comes in handy (for example) is if you have a nice rendered noise (like this level adjusted difference clouds with a grid to help show the effect):
And after running the script:
Just unzip the file into your gimp scripts directory. The script registers as Filter>Distorts>Tile Shuffle