Image coding and decoding methods, image coding and decoding apparatuses, and recording media for image coding and decoding programs
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorChoong Seng Boon
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Abstract
In an image coding method of the present invention, after a process such as DCT is performed to digital image data, quantization process is performed, and then, to resultant quantized transform coefficients, variable length coding process is performed with reference to a variable length code table showing how variable length codes are allocated, and in a comparison process between an event derived from the quantized transform coefficients and a reference event included in the variable length code table, transformation process is performed to increase a possibility of performing variable length coding with satisfactory coding efficiency.
Claims1
An image decoding method for extracting a variable length code from compression-coded data, obtaining an event corresponding to said variable length code by using a variable length code table wherein a reference event consisting of Last, Run, Level, is assigned to each reference variable length code, and deriving an output transform coefficient from said event, the method comprising:
- obtaining an event corresponding to said variable length code by using said variable length code table when said variable length code does not include a control code, and
- obtaining an event corresponding to said variable length code by using said variable length code table and then obtaining a transformed event by transforming the Run value of said event corresponding to said variable length code using a predetermined function when said variable length code includes said control code followed by a third mode code, and wherein the control code is “0000011” and the third mode code “10”.
Dependencies are inferred from the claim text.