FIELD: computer equipment.
SUBSTANCE: image decoding device which decodes a bitstream obtained from separating the differential information between the image being the decoding object and the image being the prediction object into a plurality of subblocks and encoding sub-blocks obtained as a result of division, in a given order, comprises: unit for decoding information on significant subunit, indicating equality or inequality "0" of all values of difference coefficients related to subunit; unit for decoding information on significant difference coefficient, indicating equality or inequality "0" value of difference coefficient; a decoding coefficient value decoding unit and a context extraction unit which extracts the index and the context used to decode information on the significant difference coefficient of the difference coefficient, which is the decoding object, based on said index and the position of the difference coefficient being the decoding object. Context extraction unit extracts mutually different indices in case information on significant subblock of decoded subblock, which is adjacent in horizontal direction, has value "0", and information on significant subunit of decoded subblock, which is adjacent in vertical direction, has value "0", and in case when information on significant subblock of decoded subblock, which is adjacent in horizontal direction, has value "1", and information on significant subunit of decoded subblock, which is adjacent in vertical direction, has value "0", as well as when information on significant subblock of decoded subblock, which is adjacent in horizontal direction, has value "0", and information on significant subunit of decoded subblock, which is adjacent in vertical direction, has value "1", and when information on significant subblock of decoded subblock, which is adjacent in horizontal direction, has value "1", and information on significant subunit of decoded subblock, which is adjacent in vertical direction, has value "1".
EFFECT: increase the efficiency of image decoding.
3 cl, 25 dwg
