Digital image signal coding method e.g. for Digital Video Broadcasting

摘要

The coding method provides an intra-frame coded image and a differently coded image within each group of successive images. A detector (10) responds to sharply changing image point values between one image and the next, with the coding controlled so that the image with the sharply changing image point values is subjected to the intra-frame coding, independent of its position within the successive image group. The detector provides the sum of the absolute difference values for the image points of two adjacent full-frames or half-frames, compared with a threshold value for providing a control signal for the coding.