A method and apparatus is provided for encoding/decoding an image in a process of transmission. A plurality of frequency bands are divided into different frequency zones; a scaling value is assigned for each frequency zone; a scaling matrix is established with coefficients comprising the scaling values for the different frequency zones; wherein a number of the frequency zones is smaller than a number of coefficients in the matrix, and each frequency zone corresponds to one scaling value in the coefficient matrix such that every coefficient in said each frequency zone has the same scaling value that is assigned to said frequency bands; and corresponding quantization/dequantization is performed in process of encoding/decoding respectively using the scaling matrix.