Patent ID: 8243813

Claim:
A moving picture decoding device which receives a moving picture bit stream compressed by an encoding process which utilizes interframe prediction and two-dimensional discrete cosine transform, and generates a decoded picture from an interframe prediction picture generated based on information obtained by decoding the bit stream and a result obtained by adding block-unit prediction residuals generated by performing two-dimensional inverse discrete cosine transform on discrete cosine transform coefficients found by performing inverse quantization of quantized coefficients obtained from the bit stream, the moving picture decoding device comprising: a judging device for judging as small the prediction residual of a block when the block satisfies all three following conditions: a first condition specifying that the block has a quantization step size in the inverse quantization equal to or smaller than “1”, a second condition specifying the black has a number of non-zero elements contained in the quantized discrete cosine transform coefficients is “1”, and a third condition specifying that the block has a size of the non-zero element is equal to or smaller than a threshold value; a selecting device which obtains the decoded picture by replacing the prediction residual with “0” and adding the “0”-replaced prediction residual to the interframe prediction picture for the block having the prediction residual that the judging device judged as small, and by adding the prediction residual to the interframe prediction picture for other blocks, wherein the threshold value is set for each discrete cosine transform order number of the non-zero element.