Convert hdiff to gif Online: hdiff2gif

You can use Tom's Editor to easily convert images from
Horizontal difference image .HDIFF to CompuServe Graphics Interchange Format .GIF.
Tom's Editor is a free, online image manipulation and converter program.

Go to Tom's Editor

HDIFF

Horizontal difference image is an image format with extension HDIFF.

GIF

GIF images were created by Compuserve. They can used no more than 256 colors and a single color transparenty (no Alpha channel). Today are rare since they offer low quality and huge filesizes. GIF animations are still in use.