| 摘要 |
An image encoding and decoding scheme operable according two different modes depending on properties of the processed image is disclosed. In the encoding, an image is decomposed into image blocks ( 600 ) comprising image elements ( 610 ). The blocks ( 600 ) are compressed into block representations ( 700 A, 700 B) according to one of two compression modes. A block representation ( 700 A; 700 B) comprises two codewords ( 720 A, 730 A; 720 B, 730 B) representing properties of the image elements ( 610 ) in the block ( 600 ) and a sequence ( 740 A; 740 B) of image element associated indices indicative of one of the codewords ( 720 B, 730 B) or a property representation generated based on a codeword ( 730 A). The block representation ( 700 A; 700 B) also includes a mode index representing the mode, according to which the block representation ( 700 A; 700 B) was compressed. This mode index can be provided before, during or after generation of the codewords ( 720 A, 730 A; 720 B, 730 B) and index sequence ( 740 A; 740 B). In the decoding, the codewords ( 720 A, 730 A; 720 B, 730 B) and index sequence ( 740 A; 740 B) are used to decompress the block representation ( 700 A; 700 B) according a decompression mode determined by the mode index ( 710 A; 710 B).
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