IMAGE CODING SYSTEM CAPABLE OF MONITORING AN AMOUNT OF INFORMATION BY FORMING A HISTOGRAM

摘要

In an image coding system having a plurality of coding characteristics, such as quantization characteristics, a coding control circuit (21) selects either one of the coding characteristics by forming a histogram in response to a sequence of coefficients resulting from a sequence of digital image signals, to monitor an amount of information in every one of predetermined intervals. The amount of information is calculated by summing up the coefficients in relation to every one of the coding characteristics. An optimum one of the coding characteristics is indicated by the coding control circuit to code the coefficient sequence into a sequence of coded signals in accordance with the optimum coding characteristic. The coefficient sequence in each frame may be divided into a sequence of blocks each of which is judged to be either valid or invalid in relation to each coding characteristic. Results of judgement may be included in the amount of information.