Converting music into pictures and back

The objective I had in mind was to be able to convert music into a picture and convert it back again without too much quality loss. The simplest way is of course to use a lossless format like .png and simply use the rgb values as storage for 3 bytes from for instance an mp3. But that is not very interesting. So I wanted to make it possible to use a lossy format for the picture, of which the most famous is jpeg.