./ptrwarp -w -x 320 -y 240 -a 9.762688152e-01 -b 2.648105984e-07 -c 3.396371983e-13 -o pork.ppm v050.ppm
./ptrwarp -w -x 320 -y 240 -a 1 -b 1e-40 -c 1e-40 -o pork.ppm v050.ppm