Description:

The netpbm-progs package contains a group of scripts for manipulating
the graphics files in formats which are supported by the netpbm
libraries. For example, netpbm-progs includes the rasttopnm script,
which will convert a Sun rasterfile into a portable anymap.
Netpbm-progs contains many other scripts for converting from one
graphics file format to another.

If you need to use these conversion scripts, you should install
netpbm-progs. You'll also need to install the netpbm package.