The XV program seems to have been around forever, it was first released sometime during 1990, with the current release version being 3.10a. For a long time it was not only the best image manipulation package available for UNIX, it was the only image manipulation package available for UNIX.
Despite many people using it to convert images from one format to another, XV doesn't have any support for bulk conversions, if you want to convert a lot of images from one format to another you should probably look at PBMplus. XV is definitely not a paint program, if you are interested in creating graphics you should look towards the GIMP, xpaint or xfig. While XV does have some features of a paint program they aren't that high powered, for instance I very heavily recommend against using the text annotation command in XV.
XV is primarily a graphics display and manipulation package, you can see an example of the interface in use in Figure .
Figure: The xv interface along with the Color Editor Dialog (accessed from the Windows pull down menu).
While the interface is usually fairly self explanatory, the package has a very good online manual.
The Graphics Cookbook