Is there a cygwin package that includes the linux "convert" command?

I'm trying to convert .ppm files from the P6 to the P3 (Uncompressed) convention, and there's a command on Linux that could do this quite simply. convert test.ppm -compress none output.ppm. However, the convert function from linux doesn't seem to be in cygwin (The windows convert function serves a much different purpose). Any suggestions?