APPARATUS FOR DISCRIMINATING A MOVING REGION AND A STATIONARY REGION IN A VIDEO SIGNAL

An apparatus for discriminating a region that contains motion from a region that does not contain motion in a video signal, particularly for use in an inter-frame predictive coding apparatus. The apparatus bridges across different portions of a moving region or of a stationary region to avoid small isolated regions of either type that would cause spurious responses by the encoding circuit and a resulting degradation of picture quality. The apparatus determines for each picture element a frame difference, which is the brightness difference for that picture element from one frame to the next. The picture elements are divided into a predetermined plurality of blocks. Then a first evaluation value is produced by an adder (14, 14'), which may be alternatively the sum of the absolute values of the frame differences in each block, or the number of picture elements within each block for which the absolute value of the frame difference is greater than a predetermined threshold. In certain embodiments (FIGS. 4 and 5), a comparator (15, 15') determines whether the first evaluation value exceeds a predetermined threshold, and in response outputs a first moving/stationary region signal. The first moving/stationary region signal is stored in a memory (22) and processed by a decision circuit (23) which generates a final moving/stationary region signal which has been compensated to eliminate errors due to noise. The compensation by the decision circuit can follow either of two alternative methods, namely, spatial correlation between a block and the neighboring blocks; or time correlation between the status of a given block at particular points in time. The final moving/stationary region information signal employed to control an encoding circuit. In other embodiments (FIGS. 10 and 11) the first evaluation value is weighted by weighting factors to produce a second evaluation value. The weighting is based on the first evaluation values of blocks that are close to the given block either in time sequence or in location.