CentOS 7 - Updates for x86_64: applications/multimedia: netpbm-progs
netpbm-progs - Tools for manipulating graphics files in netpbm supported formats
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.