JPEG - Idea and Practice/Appendix 1: Summary of the header segments

DQT (quantization) Marker = (255, 219) Length = (0, 67) 0 (½ byte) destination identifier (½ byte)(for instance 0 for the Y component and 1 for the colour components) the table (64 bytes) SOF (frame) Marker = (255, 192) Length = (0, 8 + 3 * number of components) 8 width = b1*256 + b2, pair (b1, b2) height = b1*256 + b2, pair (b1, b2) number of components (1-3) for each component: component identifier (for instance 0, 1, 2 for the YCbCr components) Hi (½ byte)(1 for the colour components, 1 or 2 for the Y component) Vi (½ byte)(1 for the colour components, 1 or 2 for the Y component) quantization table destination selector (for instance 0 for the Y component and 1 for the colour components) DHT (Huffman) Marker = (255, 196) Length = (0, 19 + number of Huffman values (nhv)) 0 for DC, 1 for AC (½ byte) destination identifier (½ byte)(for instance 0 for the Y component and 1 for the colour components) the list BITS (16 byte) the list HUFFVAL (nhv bytes) SOS (scan) Marker = (255, 218) Length = (0, 6 + 2 * number of components) number of components (1-3) for each component: component identifier (for instance 0, 1, 2 for the YCbCr components) destination selector of DC Huffman table (½ byte)(for instance 0 for the Y component and 1 for the colour components) destination selector of AC Huffman table (½ byte)(for instance 0 for the Y component and 1 for the colour components) 0 63 0