In an image coding system, block based motion estimation is used to determine motion vectors for blocks of pixels in a current frame or field. Only a portion of blocks from a predetermined pattern of blocks in a current frame or field are searched for a match with a block of pixels in a previous frame or field over a designated search area. Motion vectors for the blocks of the current frame or field not selected for searching are obtained by interpolation from motion vectors obtained for associated searched neighboring blocks, respectively, or by using the zero motion vector, or by performing a search over a limited range around the position defined by each of the motion vectors from neighboring blocks.

Method and apparatus for determining motion vectors for image sequences

A programmable motion estimator includes one dual ported memory for storing an image block, the prediction error, and a temporary block used in interpolation, and a pixel-group random access dual ported memory for storing a search window. The two ports of the two memories are selectively applied to an arithmetic logic unit, or ALU, through a multiplexer. One output of the ALU provides an absolute difference, which is furnished to a tree adder. Another output of the ALU provides an average value or a difference value, as selected, which is routed to the inputs of the image memory and the search memory. In motion vector searching, the ALU performs pixel absolute difference arithmetic using the pixel groups from the image memory and from the search memory, and determines a sum of absolute differences in the tree adder. In half pixel interpolation, the ALU performs pixel averaging arithmetic using pixel groups from the search memory, and writes back to the search memory. In quarter pixel interpolation, the ACU performs pixel averaging arithmetic using pixel groups from the image and search memories, and writes back to the search memory. In some quarter pixel interpolations, temporary interpolated blocks from the image memory are used to interpolated quarter pixel blocks. These temporary blocks are obtained by pixel averaging in the ALU using pixel groups from the search memory. In error prediction determination, the ALU performs pixel subtraction using the pixel groups from the image memory and from the search memory, and writes back to the image memory.

Programmable architecture and methods for motion estimation

A coder with a motion estimation system, which comprises a same parity field motion estimator, a near field motion estimator, an inter-field interpolated motion estimator, a comparator for selecting the smallest one of prediction errors E1 to E3 output from the respective motion estimators, and a selector for selectively outputting a motion vector from the motion estimator providing the smallest prediction error.

Interlaced video signal motion compensation prediction system

A system for detecting motion in a video image is provided wherein the video image is processed into a statistical array in which the array elements are derived from overlapping portions of the image. The elements of the statistical array are compared with corresponding array elements derived from an earlier image. The overlapping nature of the statistical array elements allows any detected changes in the image to be correlated with a portion of the image that is smaller than the area from which the statistical quantities are derived. Such spatial correlation of detected image changes is accomplished by thresholding and/or Boolean comparisons among the elements of the statistical array. A motion detection system in accordance with this invention can be used with a video multiplexing system so that motion cay be detected at a plurality of remote locations.

Motion detection system

A motion vector detection apparatus for a moving picture which can detect a motion vector of a half pel accuracy at a high speed by pipeline processing. The motion vector detection apparatus comprises a buffer memory for storing pel data of a search area within a reference frame required for detection of a motion vector, another buffer memory for storing peldata of an object block for motion vector detection, a half pel interpolation circuit for interpolating half pels horizontally and vertically into the pel data stored in the first buffer memory, a motion vector detection circuit for performing block matching between peldata of a search area outputted from the pelinterpolation circuit and the pel data stored in the second buffer memory and outputting a sum total of absolute values of differences between the individual pels for a plurality of candidate vectors, and a minimum value detector for detecting a minimum value of the output of the motion vector detection circuit and outputting the value of the candidate vector corresponding to the minimum value as a motion vector.

Motion vector detecting apparatus for moving picture

A motion vector suitable for motion-compensated prediction in an inter-frame differential video coder is derived by comparison of each block of a current frame and with shifted corresponding region of a previous frame with the regions of the previous frame. Rather than dealing with each block in turn, the apparatus carries out all comparisons involving a line n of the video signal before commencing comparisons involving n+p (where p is the number of lines encompassed by a block).

Ian Parke

Papers

Motion detector for video signals including a novel line comparison processing scheme

Video motion detector