Convert dgc to dds Online: dgc2dds
You can use Tom's Editor to easily convert images from
DuneGraph (compressed) .DGC to Direct Show Surface
Tom's Editor is a free, online image manipulation and converter program.
Go to Tom's Editor
DuneGraph (compressed) is an image format with extension DGC.
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.