Real time video sharpness enhancement by wavelet-based luminance transient improvement

Sharpness is a perceptual feature, which is determined by the human visual system. The human eye is more sensitive to the sharpness of the luminance signal than to that of the chrominance, however, higher resolution images, e.g. high definition images (HDTV), require the co-joint enhancement of both the luminance (black and white) and the chrominance sharpness. Even though improving the edge transitions results in an improved overall sharpness, the lack of adaptability to the picture contents produces irritating artifacts and reduces the overall impression of sharpness improvement. Other methods for sharpness enhancement used edge transition to better improve the picture quality, but either lacked adaptability to the picture contents, degraded with noisy sequences and/or required complex hardware (complex filters support and associated hardware needed for processing). We introduce a real time video sharpness enhancement method, which adaptively sharpens the picture by improving the edge transitions (variable edge enhancement at different parts of the image) using wavelet transforms. The results show a perceived desired sharpness improvement while avoiding the introduction of any artifact.