How does the old JPEG standard work?
Traditional JPEG can work according to four different philosophies: serial, progressive, hierarchic and lossless. In particular, a progressive working modality refers to the possibility of decompressing the bit-stream to a quality which is poorer than the one decided during the compression stage and to the fact that the most important bits inside the bit-stream are arranged so that they can be seen by the decoder for first (this is a particularly suitable aspect in narrow band links). The adjective hierarchic, instead, underlines the fact that inside the bit-streams there are some bits that are used to create a basic image, usually small and/or with a low resolution. Starting from this image, the further bits are used to obtain an image with higher resolution or dimension. On the contrary, lossless coding uses prediction techniques. There is the possibility that some of these approaches are applied at the same time. For instance, it is possible to apply the progressive and hierarchic m
