The invention relates to a method in image processing, wherein an image in digital form is in coding phase compressed, quantized by a quantization matrix (QL, QC) and coded by a coding matrix (HL1, HK1, HL2), wherein one or more data frames are formed. In a decoding phase decoding, dequantization and decompression is carried out to the information comprised in the data frame. One or more matrices (QL, QC, HL1, HK1, HL2) used in the coding phase are left out of the data frame, wherein the corresponding matrix is stored into coding device (8) performing the decoding phase.