Test if putImageData gives back the same result as getImageData On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS imgdata[4] is 255 PASS imgdata[5] is 0 PASS imgdata[6] is 0 PASS imgdata[4] is 0 PASS imgdata[5] is 128 PASS imgdata[6] is 0 PASS imgdata[4] is 0 PASS imgdata[5] is 0 PASS imgdata[6] is 255 PASS successfullyParsed is true TEST COMPLETE