IMAGE DECODER, PROGRAM, STORAGE MEDIUM, AND IMAGE DECODING METHOD

摘要

PROBLEM TO BE SOLVED: To provide an image decoder capable of obtaining a reproduced image with high quality.

SOLUTION: A tile boundary smoothing means 27 applies low pass filtering to tile boundaries in each frame after decoding to smooth distortions in the tile boundaries while controlling the strength of the low pass filtering used for the tile boundary smoothing means 27 in accordance with a quantization rate R, the quantization rate R related to quantization being referred to as a ratio of the number of bit planes after truncation to the number of total bit planes. Since the low pass filtering for suppressing tile boundary distortions can be applied even to an image hardly compressed as well as an image easily compressed with high accuracy by employing the ratio of the number of bit planes after truncation to the number of total bit planes for a parameter of the strength of the low pass filtering for suppressing tile boundary distortions, the reproduced image with excellent quality can be obtained.

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