Image processing method including image segmentation
First Claim
Patent Images
1. An image processing method comprising the steps of:
- a. scanning an image to produce an image signal;
b. digitizing the image signal to produce a digital image having pixel amplitude values;
c. forming an image difference signal by taking differences between successive pixel amplitude values in the digital image;
d. segmenting in segmenting means the digital image into segments of pixel amplitude values having constant variance by applying a generalized likelihood ratio test (GLRT) to the image difference signal, to identify image segments, the GLRT testing for the hypothesis H.sub.φ
that a first set of image amplitude difference values from a Laplacian distribution having a variance σ
are statistically similar to a second set of image amplitude difference values having a variance σ
0 to within a confidence level α
, where α
is an operator input value, the GLRT employing a generalized likelihood ratio (GLR) that is the ratio of maximum likelihood (ML) estimators for the variance σ
of a distribution having a Laplacian probability density function (pdf);
e. supplying said segments to image processing means;
f. processing in said image processing means the digital image employing said identified image segments to produce a processed digital image; and
g. supplying said processed digital image to an output device.
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Abstract
An image signal is segmented into regions of constant contrast or variance by applying a generalized-likelihood-ratio test to an image difference signal.
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Citations
4 Claims
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1. An image processing method comprising the steps of:
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a. scanning an image to produce an image signal; b. digitizing the image signal to produce a digital image having pixel amplitude values; c. forming an image difference signal by taking differences between successive pixel amplitude values in the digital image; d. segmenting in segmenting means the digital image into segments of pixel amplitude values having constant variance by applying a generalized likelihood ratio test (GLRT) to the image difference signal, to identify image segments, the GLRT testing for the hypothesis H.sub.φ
that a first set of image amplitude difference values from a Laplacian distribution having a variance σ
are statistically similar to a second set of image amplitude difference values having a variance σ
0 to within a confidence level α
, where α
is an operator input value, the GLRT employing a generalized likelihood ratio (GLR) that is the ratio of maximum likelihood (ML) estimators for the variance σ
of a distribution having a Laplacian probability density function (pdf);e. supplying said segments to image processing means; f. processing in said image processing means the digital image employing said identified image segments to produce a processed digital image; and g. supplying said processed digital image to an output device. - View Dependent Claims (2, 3, 4)
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Specification