640x480 is adequate. If you have a higher resolution camera or scanner, you can deliver even higher resolutions if you like. Unless we have to crop the picture heavily, the higher resolution won't help much. It is best to avoid really massive pictures, such as uncompressed high resolutions, as they can take a long time to send. But if you do, we can take them.
Some cameras save in varying compression modes.
For best results, match FaceLink size and format FaceLink adjusts all incoming photos to match the following. 224 pixels wide. FaceLink crops and resizes your picture as needed. You can submit your photo in just about any format. This usually means we use a medium JPEG compression.