System incorporating feature-oriented signal enhancement using shock filters
First Claim
1. A method for performing edge-enhancement of an N-dimensional original image containing transitions corresponding to edges in said image, said transitions corresponding to different respective edge pixel values on respective sides of a given edge, so as to produce an edge-enhanced image in data processing apparatus of the type wherein said original image is represented by an array of pixels having respective pixel values, said method comprising the following steps:
- (1. ) propagating pixel value changes toward respective edges from all sides thereof in successive iterations while prohibiting propagation of the pixel value changes across any of said edges, each said successive iteration of said propagating step comprising;
(a) computing for each one of said dimensions a respective change in the value of each respective one of said pixels toward the corresponding edge pixel value in accordance with a difference between values of said one pixel and a neighboring pixel further away from an edge nearest said one pixel along said one dimension,(b) combining the changes computed for said one pixel for each of said dimensions to produce a combined pixel value change for said one pixel, and changing said original image in accordance with the combined pixel value changes of said pixels to produce an enhanced image, and substituting said enhanced image for said original image; and
(2. ) transmitting an enhanced image of a latest iteration to an image output device for one of displaying and recording of said enhanced image.
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Abstract
A method and apparatus for enhancing signals such as images, speech, remotely sensed data, medical, tactile, radar and audio. It proceeds by the construction of certain discrete approximations to certain nonlinear time-dependent partial differential equations. These approximations preserve the variation of the discrete solution as discrete time increases for one space dimension. The approximate solutions satisfy certain maximum principles in one and two dimensions. Thus, the method enhances images and other general signals without being plagued by the phenomenon of ringing near edges and other features, or by smearing of these edges and other features, typical of the prior art. As discrete time increases the signal is enhanced. The process may reach steady state, but for some applications, the dynamical procedure is important. The method is fast, requiring only local operations on a special purpose computer described herein.
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Citations
18 Claims
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1. A method for performing edge-enhancement of an N-dimensional original image containing transitions corresponding to edges in said image, said transitions corresponding to different respective edge pixel values on respective sides of a given edge, so as to produce an edge-enhanced image in data processing apparatus of the type wherein said original image is represented by an array of pixels having respective pixel values, said method comprising the following steps:
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(1. ) propagating pixel value changes toward respective edges from all sides thereof in successive iterations while prohibiting propagation of the pixel value changes across any of said edges, each said successive iteration of said propagating step comprising; (a) computing for each one of said dimensions a respective change in the value of each respective one of said pixels toward the corresponding edge pixel value in accordance with a difference between values of said one pixel and a neighboring pixel further away from an edge nearest said one pixel along said one dimension, (b) combining the changes computed for said one pixel for each of said dimensions to produce a combined pixel value change for said one pixel, and changing said original image in accordance with the combined pixel value changes of said pixels to produce an enhanced image, and substituting said enhanced image for said original image; and (2. ) transmitting an enhanced image of a latest iteration to an image output device for one of displaying and recording of said enhanced image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for performing edge-enhancement of an N-dimensional original image containing transitions corresponding to edges in said image, said transitions corresponding to different respective edge pixel values on respective sides of a given edge, so as to produce an edge-enhanced image, wherein said original image is represented by an array of pixels having respective pixel values, said system comprising:
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(1. ) means for propagating combined pixel value changes toward respective edges from all sides thereof in successive iterations while prohibiting propagation of the combined pixel value changes across any of said edges, said means for propagating comprising; (a) means operative in each one of said successive iterations for computing for each one of said dimensions a respective change in the value of each respective one of said pixels toward the corresponding edge pixel value in accordance with a difference between values of said one pixel and a neighboring pixel further away from an edge nearest said one pixel along said one dimension, (b) means operative in each one of said successive iterations for combining the changes computed for said one pixel for each of said dimensions to produce a combined pixel value change for said one pixel, and for changing said original image in accordance with the combined pixel value changes of said pixels to produce an enhanced image, and for substituting said enhanced image for said original image; and (2. ) means for transmitting an enhanced image of a latest iteration to an image output device for one of displaying and recording of said enhanced image. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification