IMAGE ENCODING METHOD, IMAGE DECODING METHOD, IMAGE ENCODING DEVICE, IMAGE DECODING DEVICE, AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To improve encoding efficiency by suppressing a difference value between a predicted value obtained from encoded peripheral pixels and an input image.

SOLUTION: An encoding mode determination unit 61 determines whether to perform intra-encoding using bit depth conversion processing. An upper layer encoding unit 62 performs upper layer encoding for an input image signal when the bit depth conversion processing is determined not to be performed. When the bit depth conversion processing is determined to be performed, an adjacent pixel bit depth conversion processing unit 67 performs the bit depth conversion processing for an adjacent pixel, a lower layer encoding unit 68 performs lower layer encoding, and a bit depth conversion error determination unit 72 determines a bit depth conversion error. An optimum encoding mode number/division bit depth/lower layer encoding mode number encoding unit 77 encodes an encoding mode number if the bit depth conversion processing is not performed, and encodes the encoding mode number and an optimum division bit depth Δ if the bit depth conversion processing is performed.

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