Patent ID: 6449312
Filing Date: 2002-09-10
Classification: H04N

Abstract:
A method of determining a good matching reference image block from a plurality of reference image blocks in a search window of a reference image to provide a motion vector for a current image block in a current image in a video having interlaced fields, the method comprising the steps of:for each reference image block in the search window: calculating a matching criterion between each of a first plurality of discrete image elements in the current image block and each of a second plurality of discrete image elements in the reference image block, at least a first set of discrete image elements in the first plurality being in a first field of the current image and a second set of discrete image elements in the first plurality being in a second field of the current image, at least a first set of discrete image elements in the second plurality being in a first field of the reference image and a second set of discrete image elements in the second plurality being in a second field of the reference image; classifying the matching criteria according to whether the discrete image element of the first plurality is in the first field or the second field of the current image and whether the discrete image element of the second plurality is in the first field or the second field of the reference image; summing the matching criteria for each combination of sets of the discrete image elements in the current and reference images to provide two field errors out of a possible four combinations of discrete image elements which are in the: first field of the current image and first field of the reference image, first field of the current image and second field of the reference image, second field of the current image and first field of the reference image, second field of the current image and second field of the reference image; and combining the two field errors so as to include both fields in both images to provide a frame error; determining which reference image block in the search window corresponds to a good field error for each of the four combinations to provide four field candidate reference image blocks; determining which reference image block in the search window corresponds to a good frame error to provide a frame candidate reference image block; and comparing the good field error for each of the four combinations with the good frame error, to determine which of the candidate reference image blocks provides a good candidate reference image block for the current image block.