Abstract: In an image synthesizer (1), code stream analyzers (10, 11), code block extraction units (12, 13) and EBCOT decoders (14, 15) work together to decode encoded code streams (D10, D11) encoded according to the MPEG-2000 Standard and generate quantization coefficients (D16, D17) for each code block. In a cross-fading unit (16), multipliers (17, 18) multiply the quantization coefficients (D16, D17) by coefficients (&agr;(t), (1−&agr;(t))) and an adder (19) adds together the results of multiplication to provide a cross-fading quantization coefficient (D20). An EBCOT encoder (20), rate controller (21) and code stream generator (22) work together to encode the cross-fading quantization coefficient (D20) to provide a final encoded code stream (D23). Therefore, the image synthesizer (1) can combine two encoded code streams easily and effectively with a reduced use of a memory capacity.

Abstract: An error correction and encoding process is applied to a codestream being encoded in the process of encoding a picture in for example the JPEG-2000 system, or to an encoded codestream obtained by the encoding process, extremely readily and efficiently. For example, in generating an encoded codestream in accordance with the JPEG-2000 system, in a picture encoding apparatus, error correction encoding is applied to for example data of a header or to data of packets of an uppermost layer and a layer subjacent to the uppermost layer, to produce an inspection symbol, which is then embedded in its entirety in for example the lowermost layer. A picture decoding apparatus extracts this inspection symbol to perform error correction.

Abstract: A wavelet encoding method and apparatus and a wavelet decoding method and apparatus for pictures. A input picture is split into plural tile pictures and wavelet transform is applied to input pictures on the tile picture basis to effect the encoding. For wavelet transform, pixels lying on the outer side of a given tile picture are symmetrically expanded and convolved. This enables marked memory capacity reduction, while eliminating constraint conditions for the number of times of wavelet splitting.

Abstract: A wavelet encoding method and apparatus and a wavelet decoding method and apparatus for pictures. A input picture is split into plural tile pictures and wavelet transform is applied to input pictures on the tile picture basis to effect the encoding. For wavelet transform, pixels lying on the outer side of a given tile picture are symmetrically expanded and convolved. This enables marked memory capacity reduction, while eliminating constraint conditions for the number of times of wavelet splitting.

Abstract: An image signal encoded for compression using a wavelet transform as a transform system is to be decoded at a resolution corresponding to an optional rational number. To this end, the wavelet decoding device includes an entropy decoding unit 1 for entropy decoding an encoded bitstream 100, a dequantizing unit for dequantizing the quantized coefficients 101 to transmit transform coefficients 102, a transform coefficient back-scanning unit 3 for scanning the transform coefficients 102 in a pre-set fashion to re-array the transform coefficients, and an inverse wavelet transform unit 4 for inverse transforming the re-arrayed transformation coefficients 103 to furnish a decoded image 104. The inverse wavelet transform unit 4 adaptively constitutes an upsampler, a downsampler and a synthesis filter in dependence upon a pre-set resolution conversion factor.

Abstract: A method and apparatus for constructing a filter bank designed to split the frequency spectrum of digital signals into plural bands. Specifically, a low-pass analysis filter unit (H0(z)), adapted to pass frequency components of an input signal not higher than a pre-set frequency, is determined by a high-pass analysis filter unit (H1(z)) passing frequency components of the input signal not less than the pre-set frequency and a phase-linear filter unit (f(z)) having phase-linear characteristics. This enables efficient wavelet splitting of the input signal.