Reduction of Artifacts in Consumer Video using Video Processing Chain

Abstract

This paper presents a novel approach to reducing ringing artifact in color restored images by using anti –alias filtering. The performance of reducing ringing artifacts depends on the accurate classification of the local features in the image. The discrete wavelet transform (DWT) provides effective insight into both spatial and frequency characteristics of an image. Through the DWT analysis, we show that ringing artifacts can be suppressed to a  great extent by using multiple-level edge maps, which provide enhanced matching to local edges. Base on the experimental results, the proposed method can reduce ringing artifacts with minimized edge degradation by using DWT analysis.In order to circumvent the imbalance between the horizontal and vertical resolution, a tilt can be applied to orient them at a small angle to the vertical direction. To avoid aliasing the sub sampling should be preceded by suitable low pass pre-filtering. Although for purely vertical pixels a narrowband low pass horizontal filltering is needed , the situation is more complicated for diagonal pixels; the subsampling of each view is no more orthogonal, and more complex sampling models need to be considered. Based on multidimensional sampling theory, we have studied multiview sampling models based on lattices. These models approximate pixel positions on a color display and lead to optimal anti-alias filters. In this paper, results are shown for a separable approximation to non-separable 2-D anti-alias filters based on the assumption that the pixels are small. We have carried out experiments on a variety of images, and different bandwidths. We have observed that the theoretically-optimal bandwidth is too restrictive; such that aliasing artifacts disappear, but some image details are lost as well. Somewhat wider bandwidths result in images with almost no aliasing and largely preserved detail. For subjectively-optimized fillters, the improvements, although localized, are clear and enhance the hue in displays.