Abstract: When a digital video signal is compressed, the amount of resulting data is predicted and the quantization level is controlled so as to obtain a constant bit rate. The prediction is made by computing a linear combination of a standard deviation and a number of non-zero coefficients, or by computing a sum of absolute differences between adjacent pixel values, or by computing a dynamic range of pixel values. The bit rate can also be controlled by deleting high-frequency coefficients. To avoid image degradation, the quantization level can also be controlled according to the sensitivity of small image areas to quantization noise. Sensitivity is determined by dividing an area into subblocks, which may overlap, and calculating statistics in each subblock. To reduce the amount of computation required in motion estimation, chrominance motion vectors are derived from luminance motion vectors.

Abstract: When a digital video signal is compressed, the amount of resulting data is predicted and the quantization level is controlled so as to obtain a constant bit rate. The prediction is made by computing a linear combination of a standard deviation and a number of non-zero coefficients, or by computing a sum of absolute differences between adjacent pixel values, or by computing a dynamic range of pixel values. The bit rate can also be controlled by deleting high-frequency coefficients. To avoid image degradation, the quantization level can also be controlled according to the sensitivity of small image areas to quantization noise. Sensitivity is determined by dividing an area into subblocks, which may overlap, and calculating statistics in each subblock. To reduce the amount of computation required in motion estimation, chrominance motion vectors are derived from luminance motion vectors.

Abstract: An encoding apparatus which structures a band-divided digital image signal into three-dimensional blocks each having a plurality of pixels, discriminates each three-dimensional block between a moving image block and a static image block, and, in the case of a static image block, encodes only the three-dimensional blocks in the lower frequency bands while dropping the three-dimensional blocks in the higher frequency bands. However, of moving image blocks, blocks having a large pixel variance value are encoded as effective image blocks. Also, different size weightings are performed to transform coefficients depending on whether the block is discriminated as a moving image block or a static image block. Furthermore, shuffling is performed on a group of moving image blocks and a group of static image blocks independently of each other, and the transform coefficients for the static image blocks are quantized after quantizing all transform coefficients for the moving image blocks.

Abstract: In a high-efficiency encoder which performs motion-compensation prediction, an intra-field is set every n fields. The presence of a scene change is detected. When a scene change occurs, a reference picture of motion-compensation prediction is switched, or the field immediately after the scene change is set as an intra-field. In intra encoding mode, a digital video signal is encoded after dividing the digital video signal into subbands, and in predictive encoding mode, the digital video signal is encoded without dividing it into subbands.

Abstract: A coding method and apparatus is for coding a digital video signal of interlaced type. Three-dimensional (horizontal, vertical and temporal directions) blocks are constructed for each of a plurality of picture elements, orthogonal transform is performed to each of the three-dimensional blocks and coefficients are coded. Coefficients non-effected by a pseudo-moving part are weighted with a low rate, and coefficients effected by a pseudo-moving part are weighted with high rate. After the vertical positions of picture elements of odd-number fields and those of even-number fields are coincided with each other by an intra-field picture element operation, the digital video signal is formatted and three-dimensional orthogonal transform is performed.

Abstract: In a high-efficiency encoder which performs motion-compensation prediction, an intra-field is set every n fields. The presence of a scene change is detected. When a scene change occurs, a reference picture of motion-compensation prediction is switched, or the field immediately after the scene change is set as an intra-field.

Abstract: A high-efficient coding apparatus and method for compressing a digital video signal such as a color television signal, by dividing the digital video signal into a plurality of sub-bands, formatting the video signal of each sub-band into blocks per every plurality of picture elements, performing an orthogonal transform to each formatted block and coding coefficients obtained by the orthogonal transform.

Abstract: When a digital video signal is compressed, the amount of resulting data is predicted and the quantization level is controlled so as to obtain a constant bit rate. The prediction is made by computing a linear combination of a standard deviation and a number of non-zero coefficients, or by computing a sum of absolute differences between adjacent pixel values, or by computing a dynamic range of pixel values. The bit rate can also be controlled by deleting high-frequency coefficients. To avoid image degradation, the quantization level can also be controlled according to the sensitivity of small image areas to quantization noise. Sensitivity is determined by dividing an area into subblocks, which may overlap, and calculating statistics in each subblock. To reduce the amount of computation required in motion estimation, chrominance motion vectors are derived from luminance motion vectors.

Abstract: A coding apparatus, in which each block having a plurality of picture elements with digital image signals is divided into a plurality of sub-blocks, and an appropriate quantization step or weighting factor is decided on the basis of the absolute value sum of difference of image signal level between adjacent picture elements in the sub-block, so that a digital image signal is reduced. Moreover, a coding apparatus, in which each block having a plurality of picture elements with digital image signals is divided into a plurality of sub-blocks, and an appropriate quantization step or weighting factor is decided on the basis of the maximum and minimum values of the image signals of the picture elements in the sub-block, so that a digital image signal is reduced.

Abstract: A coding apparatus, in which each block having a plurality of picture elements with digital image signals is divided into a plurality of sub-blocks, and an appropriate quantization step or weighting factor is decided on the basis of the absolute value sum of difference of image signal level between adjacent picture elements in the sub-block, so that a digital image signal is reduced. Moreover, a coding apparatus, in which each block having a plurality of picture elements with digital image signals is divided into a plurality of sub-blocks, and an appropriate quantization step or weighting factor is decided on the basis of the maximum and minimum values of the image signals of the picture elements in the sub-block, so that a digital image signal is reduced.