ALREADY COMPRESSED DYNAMIC IMAGE DATA AMOUNT REDUCTION DEVICE, ALREADY COMPRESSED DYNAMIC IMAGE DATA AMOUNT REDUCTION SYSTEM AND ALREADY COMPRESSED DYNAMIC IMAGE DATA REDUCTION METHOD

摘要

PROBLEM TO BE SOLVED: To reduce further dynamic image data amount already compressed with a simple system configuration by reducing a data amount of an in-frame prediction coding frame and revising control information so as to be in matching with dynamic image data after the reduction. SOLUTION: A CPU 101 receives dynamic image data sent via a high speed communication network 111 via a communication control section 103 and gives the data to an image processing section 104, from which dynamic image data after data amount reduction processing are extracted and sent to a low speed communication network 112. The image processing section 104 applies arithmetic processing to a spatial frequency component obtained from the MPEG form dynamic image data with DCT processing and obtains the reduced spatial frequency component designated by a requested picture element number to compress the data amount. Furthermore, the inter-frame prediction coding frame in the forward direction or in two ways is replaced with dummy data to reduce a frame rate substantially. Moreover, control information representing a characteristic of the dynamic image data is revised so as to be in matching with the data amount after the reduction processing.