I too have always found this strange but I have never found a solid reason. Having an explicit declaration of intent is not a terrible feature in a data type so this is not exactly a bad choice. Also this means that a camera roll from a single sensor can be stored as an array in C since every image has the exact same size. It also does make life easier for the camera developers (but harder for photo viewer developers). If anyone knows the history here I would actually really be interested.