[libvirt] building failed

When I try to build libvirt, I meet the following error messages: ============================== Generating internals/rpc.html.tmp Validating internals/rpc.html GEN libvirt-api.xml GEN html/index.html GEN devhelp/libvirt.devhelp convert -rotate 90 libvirt-net-logical.fig libvirt-net-logical.png make[1]: convert: Command not found make[1]: *** [libvirt-net-logical.png] Error 127 ============================== The command convert does not exist. Which package should I install? PS: I find another command fig2dev can convert *.fig to *.png. Thanks Wen Congyang