12-10-2019, 02:17 PM
If these aren't too big, and you don't care much about the names (as long as you can tell which is which, using my ofn-tiles script to load all the files as a tiles in a single flat layer, apply your change to that layer, and then save the layers to multiple tiles again (also with ofn-tiles). The script lets you define a naming scheme that can use to load and/or save the files.