Patent ID: 11870994
Assignee: PEKING UNIVERSITY SHENZHEN GRADUATE SCHOOL
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 10:
11. A method for inverse quantization, comprising:
determining an initial weighted inverse quantization matrix, wherein, the initial weighted inverse quantization matrix is the same as the quantized block in size;
setting some matrix elements in the initial weighted inverse quantization matrix to zero to obtain a weighted inverse quantization matrix, wherein, determining the matrix elements that need to be zeroed according to the size of the quantized block;
weighted inverse quantizing the quantized coefficients in the quantized block to generate corresponding inverse transform coefficients, wherein, the value of the matrix element corresponding to the position of the quantized coefficient in the weighted inverse quantization matrix is used as a weight coefficient of the weighted inverse quantization;
wherein,
calculating a temporary inverse transform coefficient according to the weight coefficient and the quantized coefficient, comprising:
calculating the temporary inverse transform coefficient using Formula 1;

CoeffIT′=Clip3(−32768,32767,(((((CoeffQ*w)?ws)*D)?4)+2S+S1−1)?(S+S1)  Formula 1:

wherein:
CoeffQ is the quantized coefficient;
CoeffIT′ is the temporary inverse transform coefficient;
w is the weight coefficient;
ws is a weighted inverse quantized shift value;
D is a constant factor determined according to a quantization parameter QP;
S is a shift number determined according to the quantization parameter QP;
S1 is an additional shift number calculated according to the size of the current block and sample accuracy.