Picture encoding and/or decoding system

A method for adaptively encoding a motion picture, comprising the steps of:

• dividing input picture data into blocks, each of which includes n pixels in both horizontal and vertical direction (n .times. n) in spatial allocation;
• orthogonally transforming said picture data of each of said blocks;
• quantizing orthogonally transformed coefficients of the orthogonally transformed picture data;
• inversely quantizing said quantized data of orthogonally transformed coefficients;
• inversely orthogonally transforming said orthogonally transformed coefficients of the inversely quantized picture data;
• storing one frame of the inversely orthogonally transformed picture data;
• detecting a motion vector for each of said blocks from the respective input picture data from the respective inversely orthogonally transformed picture data, each said motion vector determining either a fast or a slow mode of motion for the respective one of said blocks;
• classifying said blocks into classes comprised of blocks of a fast motion picture region and blocks of a slow motion picture region, respectively, on the basis of the motion vector detected for each of said blocks;
• computing, for each of said blocks, a difference data between the respective input picture data and the respective stored inversely orthogonally transformed picture data;
• calculating a power of each of said blocks of said input picture data and of the respective difference data;
• and said input picture data;
• and
• adaptively changing the quantization step width in said steps of quantizing and inverse quantizing on the basis of the power calculated for each of said blocks and on the basis of the one of said classes into which the respective block is classified, so as to assign a rough quantizing step width to blocks of the fast motion picture region and a fine quantizing step width to blocks of the slow motion picture region.

A motion adaptive picture decoder for decoding coded picture data derived by:

• dividing input picture data into blocks, each of which includes n pixels in both horizontal and vertical directions (n .times. n) in spatial allocation;
• orthogonally transforming said picture data of each of said blocks;
• quantizing orthogonally transformed coefficients of the orthogonally transformed picture data;
• inversely quantizing said quantized data of orthogonally transformed coefficients;
• inverse orthogonally transforming said orthogonally transformed coefficients of the inversely quantized picture data;
• storing one frame of said inversely orthogonally transformed picture data;
• detecting a motion vector of each of said blocks of said input picture data and of the respective stored inversely orthogonally transformed picture data, each said motion vector determining either a fast or slow mode of motion for each of said blocks;
• classifying said blocks into classes comprised of blocks of a fast motion picture region and blocks of a slow motion picture region, respectively on the basis of said respective mode of motion of each of said blocks;
• computing, for each of said blocks, a difference data between the respective input picture data and the respective stored inversely orthogonally transformed picture data;
• calculating a power of each of said blocks of said input picture data and the respective difference data;
• and
• adaptively changing the quantization step width in said steps of quantizing and inverse quantizing on the basis of said power of each of said blocks and on the basis of the one of said classes into which the respective block is classified, so as to assign a rough quantizing step width to blocks of the fast motion picture region and a fine quantizing step width to blocks of the slow motion picture region, said decoder comprising:
• buffer memory means for storing said quantized data;
• inverse quantizing means for inversely quantizing said quantized data stored in said buffer memory means in correspondence to said step of quantizing;
• inverse orthogonal transforming means for inversely orthogonally transforming said inversely quantized data to said step of orthogonally transforming;
• and
• motion compensation processing means for motion compensating said picture data from said inverse orthogonal transforming means.

A motion picture encoding apparatus comprising:

• a time division multiplexing circuit for dividing picture data into a plurality of adjacent channels, said adjacent channels having border portions;
• a motion detecting circuit for detecting motion of said divided picture data and producing an output signal;
• a motion adaptive control circuit for motion compensating said output signal derived from said motion detection circuit on the basis of previous and current frame data;
• orthogonal transformation means for generating orthogonally transformed coefficients by orthogonally transforming said picture data from said motion adaptive control circuit;
• quantizing means for quantizing orthogonally transformed coefficients of picture data orthogonally transformed by said orthogonal transformation means;
• inverse quantizing means for inverse quantizing said orthogonally transformed coefficients quantized by said quantizing means;
• inverse orthogonal transformation means for inversely transforming said orthogonally transformed coefficients of said picture data inversely quantized by said inverse quantizing means;
• and
• memory means having an overlap/frame memory for storing and overlapping one frame of said picture data inversely orthogonally transformed by said inverse orthogonal transforming means,
• said motion detection circuit detects motion vector from picture data stored within said memory means and said motion picture data;
• and
• said memory means is an overlap/frame memory having said border portions of said adjacent channels being overlapped for adaptively coding said picture data, and said picture data stored within said memory means being supplied to said motion detection circuit for detecting a motion vector of said picture data.