echo Test 1.  Should print 1240379484 41
./pnminvert ../testgrid.pbm | cksum
echo Test 2.  Should print 1416115901 101484
./pnminvert ../testimg.ppm | cksum
echo Test 3.  Should print 2961441369 33838
ppmtopgm ../testimg.ppm | ./pnminvert | cksum
echo Test 4.  Should print 2595564405 14
pbmmake -w 7 7 | ./pnminvert | cksum
echo Test 5.  Should print 2595564405 14
pbmmake -b 7 7 | cksum
echo Test 6.  Should print 2595564405 14
pbmmake -b 7 7 | ./pnminvert | ./pnminvert | cksum
echo Test 7.  Should print 2896726098 15
pbmmake -g 8 8 | ./pnminvert | cksum