Compressed raster image format developed by Microsoft; used primarily for high resolution photographic images; similar to a .JPG file, but uses greater compression and also supports lossless compression.
More information about the HD Photo format is available from Microsoft's HD Photo information page.
Program(s) that open hdp files
Mac: Adobe Photoshop with HD Photo plugin Windows: Microsoft Photo Info; Microsoft HD Photo Device Porting Kit; Adobe Photoshop with HD Photo plugin; Alchemy Mindworks Graphic Workshop Professional; FastPictureViewer
Information from FileInfo.com - The File Extensions Resource.
http://www.fileinfo.com/extension/hdp
