Patent ID: 6947484

Claim:
A bit plane coding apparatus for dividing a data group including plural data with their absolute value components expressed by n bits (n being a natural number) into at least one or more blocks and coding each of the blocks by bit plane, the bit plane coding apparatus comprising: bit plane search means for searching each block for the most significant bit plane of bit planes including a bit having a valid value (value bit), the bit plane search means comprising: a storage unit for storing bit position data of the n bits in association with each block within the data group; a selection control unit for selecting the bit position data in the storage unit; and a bit OR calculating unit to which the absolute value component of each data constituting the data group is inputted and which calculates bit OR of the inputted absolute value component and the bit position data selected by the selection control unit, wherein the selection control unit reads out the bit position data of a block to which the absolute value component inputted to the bit OR calculating unit belongs, from the storage unit, then causes the OR calculating unit to calculate bit OR of the bit position data and the inputted absolute value component, stores the result of the calculation into the storage unit as new bit position data of the block, and calculates the most significant bit plane of the bit planes including a bit having a valid value (valid bit) for each block on the basis of the bit position data stored in the storage unit after all the data of the data group is inputted.