Jpeg format. This Lossy format compresses image blocks based on thresholds in the human visual This format works well for natural images.
Tiff format. This format is most commonly used to hold binary images or lossless compressed 8- or 16-bit RGB although many other options exist.
Ppm format. A lossless, uncompressed format is most often used for 8-bit RGB images although many options exist.
Png format. This is a set of lossless formats with a good set of open source management tools.