TRANSFORM METHOD, ENCODER, DECODER, AND STORAGE MEDIUM

• Main Authors: QIAO, Wenhan, YANG, Fuzheng, LI, Xinwei, HUO, Junyan, MA, Yanzhuo, WAN, Shuai
• Format: Patent
• Language: English; French; German
• Published: 08.02.2023
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; PICTORIAL COMMUNICATION, e.g. TELEVISION

Disclosed are a transform method, an encoder, a decoder, and a storage medium. The encoder determines a prediction mode parameter of a current block; when the prediction mode parameter indicates that the current block uses CCLM to determine an intra-frame prediction value, determine a CCLM parameter; according to the CCLM parameter, determine an intra-frame prediction value of the current block, and calculate a prediction difference between the current block and the intra-frame prediction value; perform first transform on the prediction difference to obtain a first coefficient matrix; when the current block uses LFNST, determine, according to the CCLM parameter, an LFNST coefficient scanning order used by the current block; use, according to the LFNST coefficient scanning order, the first coefficient matrix to construct an input coefficient matrix of the LFNST; perform LFNST processing on the input coefficient matrix to obtain a transform coefficient matrix of the current block; wherein the first transform is different from the LFNST, and the LFNST coefficient scanning order comprises a horizontal scanning order and a vertical scanning order.