An encoding device comprises: a transformer/quantizer configured to perform a transform process and a quantization process on a residual signal that represents a difference between an encoding-target block and a prediction block obtained by predicting the encoding-target block; an inverse quantizer/inverse transformer configured to restore the residual signal by performing an inverse quantization process and an inverse transform process on transform coefficients obtained by the transformer/quantizer; a combiner configured to reconstruct the encoding-target block by combining the restored residual signal and the prediction block; a deblocking filter configured to perform a filter process on a boundary between two blocks including the reconstructed block and a block adjacent to the reconstructed block; and a filter controller configured to control the deblocking filter, based on a type of the transform process applied with respect to the two blocks.

An encoding device comprises: a transformer/quantizer configured to perform a transform process and a quantization process on a residual signal that represents a difference between an encoding-target block and a prediction block obtained by predicting the encoding-target block; an inverse quantizer/inverse transformer configured to restore the residual signal by performing an inverse quantization process and an inverse transform process on transform coefficients obtained by the transformer/quantizer; a combiner configured to reconstruct the encoding-target block by combining the restored residual signal and the prediction block; a deblocking filter configured to perform a filter process on a boundary between two blocks including the reconstructed block and a block adjacent to the reconstructed block; and a filter controller configured to control the deblocking filter, based on a type of the transform process applied with respect to the two blocks.

An image decoding method according to the present document comprises a step of deriving a corrected transform coefficient, wherein the step of deriving the corrected transform coefficient comprises the steps of: determining whether LFNST can be applied to the height and width of a divided sub-partition block when an ISP is applied to a current block; parsing a LFNST index when the LFNST can be applied; and deriving the corrected transform coefficient on the basis of the LFNST index and a LFNST matrix.

According to an image coding method according to embodiments of the present document, information related to in-loop filtering may be efficiently signaled, and repetitive procedures for signaling subpicture-related information may be reduced.

According to an image coding method according to embodiments of the present document, information related to in-loop filtering may be efficiently signaled, and repetitive procedures for signaling subpicture-related information may be reduced.

Quantization matrix can be used to adjust quantization of transform coefficients at different frequencies. In one embodiment, a single fixed parametric model, such as a polynomial is used to represent a quantization matrix. Modulation of bit cost and complexity is achieved by specifying only the n first polynomial coefficients, the remaining ones being implicitly set to zero or other default values. One form of the single fixed polynomial is a fully developed polynomial in (x,y), where x,y indicate the coordinates of a given coefficient in a quantization matrix, with terms ordered by increasing exponent. Since higher exponents are the last ones, reducing the number of polynomial coefficients reduces the degree of the polynomial, hence its complexity. The polynomial coefficients can be symmetrical in x and y, and thus reducing the number of polynomial coefficients that need to be signaled in the bitstream.

Quantization matrix can be used to adjust quantization of transform coefficients at different frequencies. In one embodiment, a single fixed parametric model, such as a polynomial is used to represent a quantization matrix. Modulation of bit cost and complexity is achieved by specifying only the n first polynomial coefficients, the remaining ones being implicitly set to zero or other default values. One form of the single fixed polynomial is a fully developed polynomial in (x,y), where x,y indicate the coordinates of a given coefficient in a quantization matrix, with terms ordered by increasing exponent. Since higher exponents are the last ones, reducing the number of polynomial coefficients reduces the degree of the polynomial, hence its complexity. The polynomial coefficients can be symmetrical in x and y, and thus reducing the number of polynomial coefficients that need to be signaled in the bitstream.

An encoding device encodes each encoding-target block. The encoding device includes: a predictor configured to generate, for each of the components, a prediction block corresponding to the encoding-target block; a residual generator configured to generate, for each of the components, a prediction residual that represents a difference between the encoding-target block and the prediction block; a color space transformer configured to perform a color space transform process on the prediction residual of each of the components; a transformer configured to generate transform coefficients by performing a transform process on the prediction residual; a quantization controller configured to determine a scaling list to be used in a quantization process on the transform coefficients; and a quantizer configured to perform the quantization process on the transform coefficients by using the determined scaling list, wherein the quantization controller is configured to determine the scaling list, based on the color space transform process.

An encoding device encodes each encoding-target block. The encoding device includes: a predictor configured to generate, for each of the components, a prediction block corresponding to the encoding-target block; a residual generator configured to generate, for each of the components, a prediction residual that represents a difference between the encoding-target block and the prediction block; a color space transformer configured to perform a color space transform process on the prediction residual of each of the components; a transformer configured to generate transform coefficients by performing a transform process on the prediction residual; a quantization controller configured to determine a scaling list to be used in a quantization process on the transform coefficients; and a quantizer configured to perform the quantization process on the transform coefficients by using the determined scaling list, wherein the quantization controller is configured to determine the scaling list, based on the color space transform process.

Decoder for decoding a transformed representation of a sample block from a data stream. If a first coded coefficient is located inside a predetermined subarea of the transform coefficient block and if the underlying transform is within a first set of available transforms, the decoder decodes coefficients along a first coefficient scan order. If the transform is within a second set of In available transforms, the decoder decodes coefficients located within the predetermined subarea along a second coefficient scan order, and infers that coefficients located outside the predetermined subarea are zero. The first coefficient scan order is so that coefficients outside the predetermined subarea are scanned between two transform coefficients located inside the predetermined subarea. The second coefficient scan order does not scan any coefficient outside the predetermined subarea between scanning the coefficients within the predetermined subarea.