30 March 2000 Fixed a small bug in the sample program. For fill, the lower left corner of the image was (0, c-1) and not (0,0). To test this, I've added checker.pbm which is a weak approximation of a small checker pattern. You can see if a call to flood_fill(0,0) fills the lower right corner or not by drawing this file, filling 0,0, and drawing again to see if the lower left is filled in or not. An additional bug was pointed out today by a student. The sample program used to respond to a character other than l,s,e,f,d,x with "You must load an image first" if an image hadn't been loaded (rather than saying "Unknown command"). Since the latter would be more correct, the sample program now does that. Because of the confusion, this aspect WILL NOT BE TESTED for grading.