Topic
Median filter
About: Median filter is a research topic. Over the lifetime, 12479 publications have been published within this topic receiving 178253 citations.
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TL;DR: A class of robust weighted median (WM) sharpening algorithms is developed that can prove useful in the enhancement of compressed or noisy images posted on the World Wide Web as well as in other applications where the underlying images are unavoidably acquired with noise.
Abstract: A class of robust weighted median (WM) sharpening algorithms is developed in this paper. Unlike traditional linear sharpening methods, weighted median sharpeners are shown to be less sensitive to background random noise or to image artifacts introduced by JPEG and other compression algorithms. These concepts are extended to include data dependent weights under the framework of permutation weighted medians leading to tunable sharpeners that, in essence, are insensitive to noise and compression artifacts. Permutation WM sharpeners are subsequently generalized to smoother/sharpener structures that can sharpen edges and image details while simultaneously filter out background random noise. A statistical analysis of the various algorithms is presented, theoretically validating the characteristics of the proposed sharpening structures. A number of experiments are shown for the sharpening of JPEG compressed images and sharpening of images with background film-grain noise. These algorithms can prove useful in the enhancement of compressed or noisy images posted on the World Wide Web (WWW) as well as in other applications where the underlying images are unavoidably acquired with noise.
76 citations
TL;DR: This paper proposes a number of new methods based on the application of Taylor series and cubic spline interpolation for color filter array demosaicking that can faithfully reproduced with minimal amount of color artifacts even at edges.
Abstract: Demosaicking is an estimation process to determine missing color values when a single-sensor digital camera is used for color image capture. In this paper, we propose a number of new methods based on the application of Taylor series and cubic spline interpolation for color filter array demosaicking. To avoid the blurring of an edge, interpolants are first estimated in four opposite directions so that no interpolation is carried out across an edge. A weighted median filter, whose filter coefficients are determined by a classifier based on an edge orientation map, is then used to produce an output from the four interpolants to preserve edges. Using the proposed methods, the original color can be faithfully reproduced with minimal amount of color artifacts even at edges.
76 citations
TL;DR: A new impulse detection and filtering algorithm is proposed for restoration of images that are highly corrupted by impulse noise based on the minimum absolute value of four convolutions obtained by one-dimensional Laplacian operators.
75 citations
TL;DR: An improved segmentation approach based on watershed algorithm, neutrosophic sets (NS), and fast fuzzy c-mean clustering algorithm (FFCM) for CT liver tumor segmentation is proposed and shows that the overall accuracy offered by the employed neutrosophile sets is accurate, less time consuming, less sensitive to noise and performs better on non-uniform CT images.
75 citations
01 Sep 1993
TL;DR: A robust vision-based stop-sign reconition technique based on sequential processing of color and shape, which indicates that stop signs are successfully distinguished from other traffic sighs and background clutter.
Abstract: This paper presents a robust vision-based stop-sign reconition technique based on sequential processing of color and shape. The primary red-green-blue color coordinate system is first transformed into the saturation-hue-brightness color coordinate system. This color coordinate system allows the red color area of a stop sign to be bounded under various brightness conditions caused by weather, sun angle, or shadows. A combination of a median filter, a morphological filter, Sobel edge operator, and Hough transform is then employed to obtain the boundary contour. It is demonstrated that the parameters of eight straight lines representing the octagonal sides are sufficient for this purpose. Experimental results indicate that stop signs are successfully distinguished from other traffic sighs and background clutter.
75 citations