Can a JPEG image be used instead of a GIF image?
If you are using a program to generate a map file and the program does not accommodate JPEG images, save a copy of the image in GIF format. The JPEG when viewed has the same number of pixels as the GIF; therefore, you can map out the coordinates based on the GIF image and convert to a JPEG image later. Substitute the JPEG as your image source in your HTML. (Answer contributed by Sherwood P.