What would be the best way to go about deciphering a file format that there is no information on? I know the file is an image file, I know where the signature is, and I know where the width and height of the image are. How can I find some more info on this format? I have a way of viewing the image and I can use a hex editor . I could just go through the file changing every byte and seeing how it affects the image, but is there another way I could do it to make it easier?