images are compared as binary files, so they would have to be exactly the same in every respect to be considered equal. But two image files with exactly the same image content but saved at different times would usually have different time-stamps written into them, so the binary files would not be identical. If you are looking for the image content to be the same you need to load the images and compare them. You also have to decide whether you want to support different image file formats as being equal, such as if one person saved as TIF and the other as PNG. If that is to be allowed, you need to take into account that JPEG files are lossy and would not usually have exactly the same image content as the lossless TIF or PNG formats even if the data being written out was the same.
So first you have to define exactly what you need to compare.
