Convert psd to dds Online: psd2dds
You can use Tom's Editor to easily convert images from
.PSD to Direct Show Surface
Tom's Editor is a free, online image manipulation and converter program.
Go to Tom's Editor
PSD is in internal image format of Adobe Photoshop. It can store all the features offered by Photoshop, like layers and paths. Images can be compressed or not.
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.