Abstract: A picture is divided into either one of three types of macroblocks and then encoded in such a manner that block distortion, mosquito noise and ringing are reduced while picture coding efficiency is improved.

Abstract: In an image coding device and method for coding an image signal employing sub-band transforms, an inputted image signal is hierarchically divided into a plurality of frequency bands using sub-band transforms and a plurality of frequency band signals are generated, with each frequency band signal comprising sub-band transform coefficients. The sub-band transform coefficients of each frequency band signal are then coded using zero tree coding and run length coding in a more efficient manner than with related devices and methods.

Abstract: An image encoding method and apparatus, an image decoding method and apparatus, and an image recording medium are provided for suppress the diffusion of the quantizing noise components of the wavelet coefficient or the subband coefficient caused by the band division with the wavelet filter or the subband filter and the quantization, thereby narrowing the area where the ringing takes place.

Abstract: A sub-band encoding method for splitting the frequency spectrum of an input signal into plural bands, encoding the signals of the respective bands and transmitting the encoded signal, is disclosed. The encoding method includes a first step of splitting the input signal into a signal of a high frequency band and a signal of a low frequency band using a first-stage low-pass filter and a first-stage high-pass filter, a second step of downsampling signals of respective frequency bands obtained by the first step, a third step of splitting the frequency spectrum of the low frequency band signal downsampled by the second step, using recursively a pre-set low-pass filter and a high-pass filter, for generating signals of a plurality of frequency bands, and a fourth step of encoding the signals of respective frequency bands obtained by the second step and the third step.

Abstract: In encoding an input picture signal, the input signal is split by subband splitting into plural frequency bands for generating signals of plural frequency bands, and the signals of the respective frequency bands are quantized for generating quantized signals of the respective frequency bands. From these quantized signals of the respective frequency band, the coefficients existing at the same spatial positions of the respective layers resulting from spectrum splitting are extracted for generating a coefficient tree. This coefficient tree is S-scanned in a direction proceeding from the low frequency band towards the high frequency band for generating a scan sequence which is run-length encoded for generating encoded data. In decoding the encoded data, obtained as described above, is decoded by run-length decoding for generating a scan sequence from which a coefficient tree is re-constructed.

Abstract: A method and apparatus for sub-band encoding an input signal in which ringing may be diminished. When performing a number of wavelet transform operations by sub-band encoding, filtering the of signals is done with a small number of taps with increased number of times of spectrum splitting so far made on the signals. That is, filters with a larger number of taps are used for initial-stage frequency spectrum splitting for avoiding step-like patterns from being produced due to deterioration of low-frequency components. With increased number of times of frequency spectrum splitting, filters with a smaller number of taps are used for preventing the relative number of taps from being increased due to downsampling for suppressing picture ringing to a minimum.

Abstract: A motion picture encoding method and apparatus for adaptively switching filters in accordance with the property of a motion picture and the condition for encoding and to improve the encoding efficiency. A motion picture is encoded a plurality of times, an encoding parameter for encoding is optimized, the property of the motion picture signal is measured, and filtering is performed by using the encoding parameter or the property of the measured motion picture signal and thereby optimizing the filter characteristic only for the final-time encoding so as to practically generate and output an encoding signal (bit stream).