Method of and device for moving image contour recognition
First Claim
1. A method of recognizing the contour of a moving figure forming part of a sequence of images each of which is converted into a matrix of digital signals corresponding to a frame, the method comprising the steps of:
- (a) comparing a current frame and a preceding frame to distinguish changed image regions, thereby forming a foreground containing the figure whose contour is to be recognized, and unchanged image regions forming a background, and building up and storing an inter-frame map comprising foreground image elements;
(b) applying an edge recognition algorithm to the foreground region of the current frame to identify image elements which are candidates for the figure contour, and building up and storing an intra-frame map comprising such candidate elements;
(c) forming a logic sum of the inter-frame and intra-frame maps to build up a single map of elements, and scanning such a single map horizontally, vertically and obliquely in scanning steps, each scanning step identifying an element of a possible linear contour of an average unitary width;
(d) vectorially quantizing the elements of said possible linear contour with a neural network to generate respective contour points; and
(e) generating a continuous contour passing through the points obtained by the quantization.
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Abstract
The recognition method is applied to visual telephony image coding. Matrices of digital samples relevant to the individual frames of the video transmission are submitted to a first processing whereby the foreground region containing the figure is identified. The information concerning the elements of such a region is then processed by edge recognition algorithms to detect a group of elements possibly belonging to the contour. The group of elements is analyzed to select a sequence of elements distributed on the average along a line. The sequency of elements is processed by a neural network to build up the continuous contour which is then coded.
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Citations
13 Claims
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1. A method of recognizing the contour of a moving figure forming part of a sequence of images each of which is converted into a matrix of digital signals corresponding to a frame, the method comprising the steps of:
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(a) comparing a current frame and a preceding frame to distinguish changed image regions, thereby forming a foreground containing the figure whose contour is to be recognized, and unchanged image regions forming a background, and building up and storing an inter-frame map comprising foreground image elements; (b) applying an edge recognition algorithm to the foreground region of the current frame to identify image elements which are candidates for the figure contour, and building up and storing an intra-frame map comprising such candidate elements; (c) forming a logic sum of the inter-frame and intra-frame maps to build up a single map of elements, and scanning such a single map horizontally, vertically and obliquely in scanning steps, each scanning step identifying an element of a possible linear contour of an average unitary width; (d) vectorially quantizing the elements of said possible linear contour with a neural network to generate respective contour points; and (e) generating a continuous contour passing through the points obtained by the quantization. - View Dependent Claims (2, 3, 8)
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4. A method of recognizing the contour of a moving figure forming part of a sequence of images each of which is converted into a matrix of digital signals corresponding to a frame, the method comprising the steps of:
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(a) comparing a current frame and a preceding frame to distinguish changed image regions, thereby forming a foreground containing the figure whose contour is to be recognized, and unchanged image regions forming a background, and building up and storing an inter-frame map comprising foreground image elements; (b) applying an edge recognition algorithm to the foreground region of the current frame to identify image elements which are candidates for the figure contour, and building up and storing an intra-frame map comprising such candidate elements; (c) forming a logic sum of the inter-frame and intra-frame maps to build up a single map of elements, and scanning such a sngle map horizontally, vertically and obliquely in scanning steps, each scanning step identifying an element of a possible linear contour of an average unitary width; (d) vectorially quantizing the elements of said possible linear contour with a neural network to generate respective contour points; and (e) generating a continuous contour passing through the points obtained by the quantization, said neural network forming a self-organizing topological map, and vector quantization and continuous contour generation are obtained as a result of a network self-training step, which is repeated for each image in the sequence and during which the self-organizing topological map is caused to converge through successive approximations towards the image contour starting from an initial configuration determined in an initialization phase. - View Dependent Claims (5, 6, 7)
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9. An apparatus for recognizing a moving image contour, comprising:
means for converting an image containing a moving figure into a digital sample matrix in the form of a frame; and
means for presenting to a processor device, at each frame time, both a current frame and a preceding frame, said processor device comprising;comparing means for comparing successive frames of samples and for providing a two-dimensional bit matrix, in a one-to-one correspondence with image elements, wherein a logic value of each bit indicates whether the corresponding element belongs to a background or a foreground region, the foreground region comprising the moving figure; detecting means connected to said comparing means for detecting, among samples in each frame, those corresponding to elements which are candidates for the moving figure contour; selecting means connected to said detecting means for selecting, among the candidate elements, elements substantially placed along a line, so as to build a discontinuous contour having an average width equal to an image element; and a neural network connected to said selecting means to obtain from the discontinuous contour, by successive approximations, a continuous line representing the figure contour. - View Dependent Claims (10, 11, 12, 13)
Specification