Convert mng to dds Online: mng2dds
You can use Tom's Editor to easily convert images from
Multiple-image Network Graphics .MNG to Direct Show Surface
Tom's Editor is a free, online image manipulation and converter program.
Go to Tom's Editor
Multiple-image Network Graphics is an image format with extension MNG.
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.