Video Sharpening enhances the subjective video quality for output video processing devices. In many applications vertical and horizontal sharpening are applied independently in sequential order, where it is possible to independently control both levels of vertical and horizontal sharpening.
Video sharpening boosts the middle and high frequencies of the progressive image in vertical and horizontal directions. The middle frequencies are boosted more than the high frequencies to maintain a high level of perceptual quality. There is an issue with extra sharpening that may take place for diagonal edges or texture elements with the application of vertical and horizontal sharpening.
To resolve this issue of extra sharpening, the amount of sharpening in the diagonal direction has to be reduced. The Direction Detector for each pixel estimates the angle of the edge or texture element and based on the angle decreases the amount of vertical and horizontal sharpening by the weights WV (for vertical control) and WH (for horizontal control) that are functions of the angle value.