Moving vector extractor

DETAILED DESCRIPTION A disadvantage to the above method is that the extraction of a moving vector is greatly influenced from noises in the successive frames when the input image is low in brightness or density gradient as a whole, thereby causing errors.
The absolute value of the difference with respect to a representative point includes little information of movement at a position with low density gradient.
The moving vector calculated appears in the total searching area due to random noises as shown in FIG.
4.
The calculation precision is extremely low.
It is therefore an object of the present invention to improve the precision of moving vector extraction by weighting a basic data of a moving vector according to the density gradient value.
According to the present invention, moving a vector extractor comprises a means for obtaining the difference value between successive frames with a predetermined time distance for representative points, in a predetermined area, a means for calculating a density gradient value around a representative point, a means for obtaining a basic data of moving vector for the difference value between frames by calculating an absolute value or a squared value, a means for weighting basic data of moving vector according to density gradient value, a means for extracting moving vector, through calculation of accumulation addition of a basic data of weighted moving vector for each representative point, and calculation of a local minimum of the accumulating addition.