Convert atk to dds Online: atk2dds

You can use Tom's Editor to easily convert images from
Andrew Toolkit raster object .ATK to Direct Show Surface .DDS.
Tom's Editor is a free, online image manipulation and converter program.

Go to Tom's Editor

ATK

Andrew Toolkit raster object is an image format with extension ATK.

DDS

DDS are files invented by Microsoft to be used in games, mostly as textures. Images can be compressed to save space but the compression methods defined by DDS are all very fast in terms of coding and decoding.