PROBLEM TO BE SOLVED: To correct a prediction signal for an invalid prediction mode to raise a selection probability of the invalid prediction mode having a very small selection probability, in order to improve the coding efficiency.;SOLUTION: A prediction signal generation portion 15 generates a prediction signal from an encoded image signal in a memory 14. An invalid prediction mode determination portion 16 detects an invalid prediction mode from the generated prediction signal for each prediction mode. A prediction signal correction portion 17 corrects the prediction signal in the detected invalid prediction mode. A prediction mode determination portion 18 computes a coding cost for each prediction mode using the corrected prediction signal and selects a prediction mode with a minimum cost. Then, the prediction signal of the selected prediction mode is sent to a subtractor 10, and a prediction mode information is sent to a coding portion 19.;COPYRIGHT: (C)2006,JPO&NCIPI
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