Process and device for sequential image transformation
First Claim
1. Process for skeletonization of an image made up of a matrix of pixels, wherein each of the pixels constitutes a central pixel in a neighborhood consisting of a predetermined plurality of pixels adjacent to the central pixel, each of the pixels in said matrix presenting a characteristic feature, such as a brightness, defined by a digital value, said method comprising the steps of:
- (a) transforming said image by eliminating its plateaus to generate a relief without plateaus;
(b) coding said relief without plateau in the neighborhood of each of said pixels according to a predetermined coding algorithm to provide a coded relief represented by coded values;
(c) marking peak points on said coded relief, said peak points belonging to a skeleton of shapes in said image; and
(d) starting from said peak points, generating upstream parts of said skeleton by a re-write transformation including;
(d1) a first scan of the image in a direct direction, during which a value is selected for each pixel in the image which is responsive to values of a set of pixels within a structuring element associated with the pixel whose value is to be selected and identical for all pixels;
the selected value of each pixel is immediately substituted for the coded value in a image memory, whereby the pixel values in said structuring element include coded values and already selected values; and
(d2), after symmetry or rotation of the structuring element, repeating step (d1) using a reversed direction scan, at least once.
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Abstract
The transformation applies to images defined by pixels each presenting a characteristic, such as a brightness, defined by a digital value, with the pixels being distributed according to a matrix and their relations and distances established by a neighborhood graph. All or part of the image is explored according to a predetermined exploration mode and the value of each pixel is modified as a function of the values of a set of associated pixels, assuming their value in at least the image and being located inside a sliding window related to the pixel to be transformed, identical for all pixels and constituting a structuring element. The transformed version of each pixel is immediately substituted for the preceding value in an image memory. To implement the process, a device can be utilized having a morphological opening processor, an image memory and a morphological processor with rewrite processing.
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Citations
17 Claims
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1. Process for skeletonization of an image made up of a matrix of pixels, wherein each of the pixels constitutes a central pixel in a neighborhood consisting of a predetermined plurality of pixels adjacent to the central pixel, each of the pixels in said matrix presenting a characteristic feature, such as a brightness, defined by a digital value, said method comprising the steps of:
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(a) transforming said image by eliminating its plateaus to generate a relief without plateaus; (b) coding said relief without plateau in the neighborhood of each of said pixels according to a predetermined coding algorithm to provide a coded relief represented by coded values; (c) marking peak points on said coded relief, said peak points belonging to a skeleton of shapes in said image; and (d) starting from said peak points, generating upstream parts of said skeleton by a re-write transformation including;
(d1) a first scan of the image in a direct direction, during which a value is selected for each pixel in the image which is responsive to values of a set of pixels within a structuring element associated with the pixel whose value is to be selected and identical for all pixels;
the selected value of each pixel is immediately substituted for the coded value in a image memory, whereby the pixel values in said structuring element include coded values and already selected values; and
(d2), after symmetry or rotation of the structuring element, repeating step (d1) using a reversed direction scan, at least once. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification