Image processing apparatus and image processing method

摘要

A variable-length code stream is read out from a position designated as a start position of an encoded stream of a block of interest, and the readout stream is decoded. Upon completion of the decoding of the variable-length code stream of the block of interest, a data length of a semi-fixed-length data stream of the block of interest is calculated. A position the data length behind the start position of the semi-fixed-length data stream is designated as a start position of an encoded stream of a next block to be decoded after the block of interest, and decoding of a variable-length code stream of the next block is started.

主权项

1. An image processing apparatus, which entropy-decodes an encoded stream obtained by encoding coefficients obtained by applying orthogonal transform to an image for each macroblock, in which a variable-length code stream and a semi-fixed-length data stream are alternately coupled in each of at least two blocks included in a target macroblock, comprising:
a read out unit that reads out the encoded stream in which a variable-length code stream of N-th block (N is an integer equal to or larger than 1) in the target macroblock, a semi-fixed-length data stream of the N-th block in the target macroblock, a variable-length code stream of (N+1)-th block in the target macroblock, and a semi-fixed-length code stream of the (N+1)-th block in the target macroblock are arranged in this order; a first decoding unit decodes each variable-length code stream included in the encoded stream; a second decoding unit that decodes the semi-fixed-length data stream of the N-th block after the decoding of the variable-length code stream of the N-th block by said first decoding unit; a determination unit that determines, after the decoding of the variable-length code stream of the N-th block, a total data length of the semi-fixed-length data stream of the N-th block following the variable-length code stream of the N-th block using the number of significant coefficients obtained by the decoding of the variable-length code stream of the N-th block by the first decoding unit and the number of bits of each semi-fixed-length data stream of the target macroblock; and wherein said read out unit designates a position the total data length behind a start position of the semi-fixed-length data stream of the N-th block as a start position of the variable-length code stream of the (N+1)-th block following the semi-fixed-length data stream of the N-th block in the target macroblock, read out the variable-length code stream of the (N+1)-th block from the designated position and controls said first decoding unit to start decoding of the variable-length code stream of the (N+1)-th block, wherein said first decoding unit decodes the variable-length code stream of the (N+1)-th block in parallel with decoding the semi-fixed-length data stream of the N-th block by said second decoding unit, in a spatial mode of JPEG XR.