that’s an 8 bit indexed image. i’d call that ancient. could well imagine there’s a bug somewhere, since noone really uses indexed images anymore for like more than a decade now.
may i ask why not simply convert it to png? i mean it works right?
Anyway, if it is ancient or not, it is just a BMP.
I make a renderer for a game called Ragnarok Online, and it uses that ancient format for their textures. I would like to render based on the original game files, so i can’t convert it.