Convert dds to sgi Online: dds2sgi
You can use Tom's Editor to easily convert images from
Direct Show Surface
.DDS to Silicon Graphics RGB .SGI.
Tom's Editor is a free, online image manipulation and converter program.
Go to Tom's Editor
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.
Silicon Graphics RGB is an image format with extension SGI.