ENCODER, DECODER, AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To improve coding efficiency by predicting an orthogonal transformation type without using an identifier of the orthogonal transformation type when multiple different types of orthogonal transformation is used.

SOLUTION: An inverse transformation processing unit 2 of an orthogonal transformation type predictor 1 performs multiple different types of inverse orthogonal transformation to an orthogonal transformation coefficient string. An addition unit 3 adds prediction signals to signals performed inverse orthogonal transformation to generate decoded signals respectively. A comparison unit 4 generates an adjacent difference signal by comparing the decoded signal in each lineage and its adjacent decoded signal. A selection unit 5 determines a lineage by comparing the adjacent difference signals of each lineage. Then, the selection unit 5 predicts that the orthogonal transformation type of the determined lineage is a right type and selects a decoded signal with its orthogonal transformation type. This makes it possible to predict the orthogonal transformation type on the basis of an orthogonal transformation coefficient string without using an identifier of the orthogonal transformation type.

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