Mode partition of high‐definition television signals using adaptive subsampling

Abstract

AbstractIn the analog transmission of high‐definition television signal using satellites, the transmission must be performed within a limited band. For this purpose, an adaptive subsampling system is proposed and is used in the highly efficient transmission of the high‐definition television signal. One of the important problems in the adaptive subsampling for improving the picture quality is to partition the picture into as many subsampling modes as possible in an efficient way.This paper proposes an adaptive subsampling system with four different subsampling modes. The four modes are composed of three modes for the moving part and one mode for the still part. Discussions are made on the partitioning of three modes in the moving part, and the partitioning between moving and still parts. In the mode partitioning in the moving part, a method (histogram method) is proposed where the distortion over the whole picture is reduced, based on the histogram derived from the distortion for each subsampling block to determine the subsampling mode partitioning.The proposed method is compared with the traditional method by computer simulation, and it is verified that the SN ratio is improved by the proposed method. As to the partitioning between moving and still parts, a control method for the motion detection threshold is proposed, which seeks a balance between the distortions of still and moving parts. The performance of the control method is verified by a computer simulation for the picture data containing a scene change. Finally, the usefulness of the proposed method is verified by a simulation using motion pictures.