Method for detecting and separating the shadow of moving objects in a sequence of digital images
First Claim
1. A method for detecting and separating shadow of moving objects in a sequence of digital images, comprising the steps of:
- a) determining a sequence of background images from the sequence of digital images, said sequence of background images containing only the non-moving image background of the sequence of images but not the moving objects;
b) determining, for extracting object edges, in each case an edge gray-value image for each image of the sequence of digital images and for each respective corresponding background image of the sequence of background images;
c) determining, by means of vertical or horizontal projection of said edge gray-value images, corresponding vertical or horizontal edge histograms in each case for the edge gray-value images;
d) eliminating edges which do not belong to moving objects or shadows, in that edge histograms of a background image are subtracted from corresponding edge histograms of an image, at a common instant in time, of the sequence of digital images, thereby forming differential edge histograms;
e) subjecting the differential edge histograms to a threshold value discrimination, to eliminate those edges which do not correspond to actual moving objects but which do correspond to a shadow of a moving object.
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Abstract
For detecting and separating the shadow of moving objects in a sequence of digital images, a sequence of background images is first determined from a sequence of images, this sequence of background images containing only the non-moving image background of the sequence of images but not the moving objects. Object edges are then extracted from the sequence of images in that in each case an edge gray-value image is determined for each image of the sequence of images and for each respective corresponding background image of the sequence of background images. Using vertical or horizontal projection of these edge gray-value images, corresponding vertical or horizontal edge histograms are determined in each case for the edge gray-value images. Edges which do not belong to moving objects or shadows of moving objects are eliminated, in that the edge histograms of a background image are subtracted from the corresponding edge histograms of the image, belonging to the same instant, of the sequence of images and in that the differential edge histograms formed in this manner are subjected to a threshold value discrimination, by which means those edges are eliminated which do not correspond to the actual moving objects but rather to a shadow of a moving object.
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Citations
6 Claims
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1. A method for detecting and separating shadow of moving objects in a sequence of digital images, comprising the steps of:
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a) determining a sequence of background images from the sequence of digital images, said sequence of background images containing only the non-moving image background of the sequence of images but not the moving objects; b) determining, for extracting object edges, in each case an edge gray-value image for each image of the sequence of digital images and for each respective corresponding background image of the sequence of background images; c) determining, by means of vertical or horizontal projection of said edge gray-value images, corresponding vertical or horizontal edge histograms in each case for the edge gray-value images; d) eliminating edges which do not belong to moving objects or shadows, in that edge histograms of a background image are subtracted from corresponding edge histograms of an image, at a common instant in time, of the sequence of digital images, thereby forming differential edge histograms; e) subjecting the differential edge histograms to a threshold value discrimination, to eliminate those edges which do not correspond to actual moving objects but which do correspond to a shadow of a moving object. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification