ENCODING AND DECODING DEVICES FOR THREE-STAGE CASCADE PICTURE

摘要

PURPOSE: To provide three-stage cascade picture encoding and decoding devices for executing a super low bit rate encoding and decoding. CONSTITUTION: In three-stage compression processing, a non-linear sub-sampling means 2 is used for 1st processing, a B spline surface approximating means 4 is used for 2nd processing and a DCT transformation encoding means 6 is used for 3rd processing. A picture is divided into plural blocks with variable size in accordance with its contents by using the spatial redundancy of the picture. Non-linear sub-sampling processing is applied to a block larger than 8×8 (1st compression). The original or sub-sampled 8×8 block data are approximated by B spline surface approximation algorithm and compressed to a group of a control point and a small parameter (2nd compression). The control point is furthermore encoded by DCT.