To solve such a problem that a high coding rate is required for transmission of quantization parameters.
In an image decoder which decodes a video signal by using quantization parameters, an entropy decoding unit 205 decodes the information indicating the prediction type of prediction quantization parameters and the differential quantization parameters from a stream where the information indicating the prediction type of prediction quantization parameters and the differential quantization parameters are encoded. A quantization parameter prediction method determination unit 210 determines the prediction quantization parameters from the quantization parameters of a plurality of decoded blocks, based on the information indicating a decoded prediction type in units of predetermined blocks. A quantization parameter calculation unit 211 calculates the quantization parameters by adding the prediction quantization parameters thus determined and the decoded differential quantization parameters.
NAKAMURA HIROYA
TAKEHARA HIDEKI
UEDA MOTOHARU
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