IMAGE ENCODING APPARATUS, IMAGE DECODING APPARATUS AND PROGRAM OF THEM

摘要

PROBLEM TO BE SOLVED: To provide an image encoding apparatus, an image decoding apparatus and programs thereof which select one orthogonal transformation from a plurality of types of orthogonal transformations and compress unit blocks of an image signal into a frequency domain by the orthogonal transformation.

SOLUTION: An image encoding apparatus 10 includes: a reference transformation basis calculation section 201 for transforming a plurality of blocks into a frequency domain by a reference transformation, which calculates an orthogonal transformation basis depending on an image signal; a fixed transformation basis selection section 202 for selecting block-specific bases most similar to the basis of the reference transformation from a plurality of fixed transformation basis candidates stored in a fixed transformation basis storage section 203 which are related to fixed transformations having fixed orthogonal transformation bases for image signals; and an entropy encoding section 30 for entropy-encoding orthogonal transformation coefficients to generate an encoded stream including transformation basis numbers of the selected bases. An image decoding apparatus 50 applies an inverse frequency transformation using inverse fixed transformation bases corresponding to the transformation basis numbers.

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