The application discloses a method, system, device and computer-readable storage medium for inverse quantization, wherein, in some embodiments, determining whether the inverse transform coefficient corresponding to the quantized coefficient in the quantized block can be set to 0, according to the size of the quantized block; when the inverse transform coefficient corresponding to the quantized coefficient can't be set to 0, the quantized coefficient is inverse quantized to obtain a corresponding inverse transform coefficient. Compared with the prior art, the inverse quantization method provided by the embodiments of the present invention controls the non-zero coefficient in the inverse transform block obtained by inverse quantization to be in a suitable region by performing zeroing determination before the inverse quantization calculation, thereby reducing the complexity of the inverse transform block, thereby effectively reducing the complexity of the inverse transform process and reducing the difficulty of implementing decoder.

A quantization scheme substitutes the division operation by forward and inverse quantization look-up tables to improve efficiency.

A method for decoding a data signal representative of at least one image cut into blocks. The method includes, for a current block to be decoded: transforming a residual data block obtained from the data signal; determining a permutation-transformation pair including a transformation mathematical operation and a permutation mathematical operation, the transformation mathematical operation and the permutation mathematical operation belonging to respectively a plurality of permutation operations and a plurality of transformation operations; applying the determined transformation mathematical operation to the data of the residual data block to produce transformed data; applying the determined permutation mathematical operation to the transformed data to produce permuted data, the determined permutation mathematical operation being an operation of transposing the transformed data; and using the permuted data to reconstruct the current block by a predictive decoding.

The present invention avoids waste caused by performing both a Secondary Transform and an Adaptive Multiple Core Transform. Provided is a device including: a core transform unit (1521) that can perform an Adaptive Multiple Core Transform on a Coding Tree Unit; and a Secondary Transform unit (1522) that can perform, before the Adaptive Multiple Core Transform, a Secondary Transform on at least any one of sub-blocks included in the Coding Tree Unit. The device omits any of the Adaptive Multiple Core Transform and the Secondary Transform in accordance with at least any of a flag associated with the Adaptive Multiple Core Transform and a flag associated with the Secondary Transform, or in accordance with a size of the Coding Tree Unit.

A decoder (400) configured to receive a first output video and one or more further encoded streams (416, 428), decode respective frames of the one or more further encoded streams to derive respective sets of residuals; and combine (470) the sets of residuals with the first output video to generate a reconstructed output video (448). Each frame is divided into a plurality of tiles and each tile is divided into a plurality of blocks. To decode respective frames, the decoder is configured to obtain (440, 446) a preliminary set of residuals from the one or more further encoded streams, derive a set of temporal predictions using a temporal buffer (432), and combine (468) the set of temporal predictions with the preliminary set of residuals. The decoder is configured to provide for zeroing of values of the set of temporal predictions at a frame level, at a tile level and at a block level.

An image decoding apparatus comprises a selector configured to select, from a set of candidate prediction operations each defining at least a prediction direction, a prediction operation for prediction of samples of a current region of a current image, the current region comprising an array of two or more rows and two or more columns of samples; and an intra-image predictor configured to derive predicted samples of the current region with respect to one or more of a group of reference samples of the same image in dependence upon a prediction direction, defined by the selected prediction operation, between a current sample to be predicted and a reference position amongst the reference samples; in which, for at least some of the candidate prediction operations, the group of reference samples comprises two or more parallel linear arrays of reference samples disposed at different respective separations from the current region.

Coding efficiency is improved. A motion compensation filter unit acts on a motion vector applied image obtained by acting a motion vector on a reference image. The motion compensation filter unit causes filter coefficients mcFilter[i][k] designated by a phase i and a filter coefficient position k to act on the motion vector applied image. The filter coefficients mcFilter[i][k] includes filter coefficients calculated by using filter coefficients mcFilter[p][k] (p≠i) and filter coefficients mcFilter[q][k] (q≠i).

In image encoding, to raise the degree of concentration of coefficient energy (concentrate the transform coefficients at low frequencies), there is disclosed the application of a secondary transform different from a primary transform to the transform coefficients after the primary transform. Since the transform coefficients after multiple transforms are applied may be transformed to a different domain than the frequency domain with respect to the original image characteristics, bandwidth control using a scaling list for the frequency domain (quantization matrix) is affected. It is an object to provide a mechanism enabling bandwidth control using a scaling list. The present invention provides an image processing apparatus including a process control section that controls a scaling list process based on transform information related to a transform applied to a processing target block (information indicating whether or not a predetermined transform has been applied, information indicating the number of transforms, etc.).

Coding efficiency is improved. A motion compensation filter unit acts on a motion vector applied image obtained by acting a motion vector on a reference image. The motion compensation filter unit causes filter coefficients mcFilter[i]-[k] designated by a phase i and a filter coefficient position k to act on the motion vector applied image. The filter coefficients mcFilter[i][k] includes filter coefficients calculated by using filter coefficients mcFilter[p][k] (p≠i) and filler coefficients mcFilter[q][k] (q≠i).

An image decoding method and apparatus according to an embodiment may extract, from a bitstream, a quantization coefficient generated through core transformation, secondary transformation, and quantization; generate an inverse-quantization coefficient by performing inverse quantization on the quantization coefficient; generate a secondary inverse-transformation coefficient by performing secondary inverse-transformation on a low frequency component of the inverse-quantization coefficient, the secondary inverse-transformation corresponding to the secondary transformation; and perform core inverse-transformation on the secondary inverse-transformation coefficient, the core inverse-transformation corresponding to the core transformation.