Graphic PhotoDefiner Image File
The program PhotoDefiner is used to compress images so that the hard drive space needed is smaller, there are files used by PhotoDefiner which contains the image these are known as Graphic PhotoDefiner Image file which use the extension .gpd.
GPD files make use of lossless compression which means that despite the file sizes being smaller after compression the quality remains the same.
How to open .gpd files?
Software to open .gpd files
What are .gpd files