Convert rfg to dds Online: rfg2dds

You can use Tom's Editor to easily convert images from
LEGO Mindstorms EV3 Robot Graphics File .RFG to Direct Show Surface .DDS.
Tom's Editor is a free, online image manipulation and converter program.

Go to Tom's Editor

RFG

LEGO Mindstorms EV3 Robot Graphics File is an image format with extension RFG.

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.