| 摘要 |
FIELD: information technologies. ^ SUBSTANCE: matrix of frequency coefficients of a video image is calculated at the transmitting side by doing an operation of two-dimensional cosine conversion. Then 2p coefficients of two-dimensional linear forecasting (TDLFC) are calculated in a matrix of quantised counts of a fixed halftone image and are sent into a digital communication channel. The TDLFC quantised values are used to form an envelope of frequency coefficients, which is applied to determine coordinates of frequency coefficients in the order of their absolute values decreasing. Then values of frequency coefficients corresponding to the found coordinates are quantised and sent to the communication channel. When recovering messages on the basis of TDLFC received from the communication channels, an envelope of frequency coefficients is formed, using which, coordinates are assigned to the received frequency coefficients in the structure of their matrix, and the video image is recovered by doing an operation of a reverse two-dimensional discrete cosine conversion above the recovered matrix of frequency coefficients. ^ EFFECT: provision of compression and recovery of fixed halftone images with reduction of information transfer speed with preservation of the specified recovery quality. ^ 4 cl, 14 dwg, 1 app |
