Patent ID: 6456659
Filing Date: 2002-09-24
Classification: G06T,H04N

Abstract:
A method of motion estimation from common fields or pictures of successive images for video coders, the method comprising the steps of:dividing each picture of N lines and M columns to be subjected to motion estimation into a plurality of (N/R)*(M/S) reference macroblocks, each comprising R lines and S columns of pixels; defining for each of the reference macroblocks a set of P+Q+2*D predictor macroblocks comprising at least a component between a luminance and a chrominance component disposed on a preceding picture, and wherein 1) P predictors are generated by the use of motion vectors associated to macroblocks preceding the reference macroblocks on the same picture according to a raster scanning, by projecting vectors on the macroblock common to the reference macroblock and disposed on the preceding picture, 2) Q predictors are generated by the use of motion vectors associated to macroblocks following the reference macroblock on the preceding picture according to a raster scanning, by projecting vectors on the macroblock common to the reference macroblock placed on the preceding picture, 3) 2*F predictors are generated by the use of the motion vectors associated to P and Q predictor macroblocks as defined above and summed to integer and/or fraction quantities predefined in look-up tables, 4) calculating per each pair of macroblocks comprising only one among the P or Q or 2*F predictors and the reference macroblock, an L1 norm, the L1 norm being the sum of the differences in absolute values between common pixels belonging to the pairs of macroblocks, 5) identifying a minimum value of the L1 norms and calculating x and y components of the motion vector associated to the reference macroblock as the difference between the common coordinates of a first pixel, according to a raster scanning of the reference macroblock, and the predictor with minimum distortion; and employing a recursive procedure based on a correlation existing among motion vectors associated to macroblocks adjacent to the reference macroblock during the processing of a picture to reduce a total number of operations by: storing the motion vectors associated to all the macroblocks of a picture, overwriting them one by one with the motion vectors associated to corresponding macroblocks of a following picture during the processing thereof, and as the motion vectors are calculated in succession following a raster type of scanning of the macroblocks, and using the stored motion vectors already calculated, associated to the P macroblocks and the stored motion vectors associated to the Q macroblocks, noncommon to the P macroblocks adjacent to the reference macroblock during the processing of a current picture for addressing P+Q predictor values.