png2pnm img_0000
png2pnm img_0100
png2pnm img_0150
png2pnm img_0190

cd pnm
pnmcat -lr img_0000.pnm img_0100.pnm > 1.pnm
pnmcat -lr img_0150.pnm img_0190.pnm > 2.pnm
pnmcat -tb 1.pnm 2.pnm > C.pnm
convert C.pnm C.jpg
jpeg2ps C.jpg > ~/tex/fabio/spatcomp/fig/C.ps

