IMAGE CODING METHOD BASED ON NON-SEPARABLE SECONDARY TRANSFORMATION AND DEVICE FOR IT Russian patent published in 2021 - IPC H04N19/40 H04N19/176 H04N19/18 H04N19/186 H04N19/119 H04N19/70 H04N19/167 

FIELD: image coding.

SUBSTANCE: invention relates to devices for image coding. To achieve the technical result, the transformation coefficients of the target block are extracted from the bit stream. The Index of the Non-Separable Secondary Transformation (NSST) for the target block is then obtained. Residual samples of the target block are obtained by performing an inverse transformation on the transform coefficients of the target block based on the NSST index. A reconstructed frame is generated based on the residual samples. Based on the fact that the NSST index value is not 0, the residual samples are obtained by performing an inverse NSST transform on the transform coefficients located in the upper left target area of the target block based on the transform matrix indicated by the NSST index. In this case, the size of the transformation matrix is R × N, where N is the number of samples of the upper left target area, and R is less than N.

EFFECT: invention is aimed at increasing efficiency of image compression.

11 cl, 18 dwg, 5 tbl