Patent ID: 7957604
Filing Date: 2011-06-07
Classification: H04N

Abstract:
1. A moving image coding apparatus that sequentially inputs and codes image data of frames constituting a moving image, the apparatus comprising: a mode selection unit that adaptively selects, for each frame, either a first coding mode or a second coding mode, where the first coding mode is for coding a frame by referring to another frame using an inter-frame coding method and the second coding mode is for coding a frame without referring to another frame using an intra-frame coding method; a storage unit that stores a frame image as a reference frame to be referred in the first coding mode; a segmentation unit that segments image data of a current input frame into a plurality of blocks; a computation unit that (i) extracts, from the reference frame stored in said storage unit, predicted data for a segmented block image of the current input frame obtained by said segmentation unit and outputs a block obtained by subtracting the predicted data from the segmented block image, if the mode for the current input frame selected by said mode selection unit is the first coding mode, or (ii) outputs the segmented block image of the current input frame obtained by said segmentation unit, if the mode of the current input frame selected by said mode selection unit is the second coding mode; a transformation unit that executes discrete wavelet transformation for the block obtained by said computation unit to obtain spatial frequency component data; a code data generating unit that encodes the spatial frequency component data for each bitplane to generate code data for each bitplane; an adjusting unit that adjusts a code data amount by discarding code data corresponding to bitplanes from a least significant bit position to a predetermined bit position; an output unit that outputs remaining code data from said adjusting unit as the code data of the segmented block; and a decoding unit that, only when said mode selection unit selects the second coding mode for the input current frame, performs bit-shifting of the code data of the current input frame by a number of discarded bitplanes by said adjusting unit, decodes the bit-shifted code data of the current input frame, and stores the decoded image of the current input frame as the reference frame into said storage unit.