Image encoder and image encoding method

A method comprising:

• chromatically subsampling an externally input image signal and arranging the image signal in units of a plurality of blocks;
• performing Discrete Cosine Transform (DCT) with respect to the image signal divided into the plurality of blocks;
• quantizing the DCT signals;
• performing Differential Pulse Code Modulation (DPCM) with respect to the quantized signals;
• performing Huffman encoding with respect to the DPCM signals;
• and then reconstructing the Huffman-encoded signals in constant bit units and outputting a compressed image signal.

An apparatus comprising:

• a block arrangement unit configured to chromatically subsample an externally input image signal and arrange the image signal in units of a plurality of blocks;
• a plurality of Discrete Cosine Transform (DCT) units configured to perform DCT with respect to the image signal divided into the plurality of blocks;
• a plurality of quantization units configured to quantize the outputs of the plurality of DCT units;
• a delta modulation unit configured to perform Differential Pulse Code Modulation (DPCM) with respect to the outputs of the plurality of quantization units, the delta modulation unit including a circuit configured to divide the blocks of the outputs of the plurality of quantization units, insert a reset marker in constant units, and determine whether the blocks are subjected to the DPCM through the reset marker;
• a plurality of Huffman encoding units configured to encode the outputs of the delta modulation units using a Huffman encoding method;
• and
• a code connection unit configured to reconstruct the signals output from the plurality of Huffman encoding units in constant bit units and to output a compressed image signal, the code connection unit including a circuit configured to divide the outputs of the plurality of Huffman encoding units in constant block units and insert a reset marker.