System and method for detecting and analyzing a queue
First Claim
1. A system for detecting persons standing in a queue, comprising:
- (a) a video camera positioned to view a selected area of interest, the video camera providing a video signal output;
(b) a frame grabber for converting the video signal output into a digital video image;
(c) a processing system for analyzing the digital video image, the processing system performing the following steps;
(1) dividing the digital video image into a plurality of slots, each slot approximately the size of a person within the digital video image;
(2) generating an image difference for each slot;
(3) determining from the image difference whether a slot is occupied by a person; and
(4) determining whether a person overlaps adjacent slots, if it is determined that neither adjacent slot is occupied by a person, by defining a slot overlapping the adjacent slots and detecting whether the overlapping slot is occupied by a person.
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Abstract
A system and method are provided for detecting, collecting information about, and analyzing a queue. A video camera is positioned to view the queue, and a sequence of video images from the camera may be processed in order to perform the functionality of the present invention. The present invention may be implemented at checkout lanes in a retail establishment, in a bank, at customer service desks, at self-service kiosks, at banks, or any other location where a queue (line) of people or other objects may form. After detecting the queue, the present invention, may collect multi-dimensional information regarding the queue, including the number of people, etc., in the queue, the average service time for each person in the queue, as well as various other types of information regarding the queue. The present invention may thereafter analyze the collected information in various ways, based upon various criteria. For example, a retailer may use the analyzed information to minimize service time for people in a checkout line, in a way which makes economic sense.
99 Citations
13 Claims
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1. A system for detecting persons standing in a queue, comprising:
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(a) a video camera positioned to view a selected area of interest, the video camera providing a video signal output;
(b) a frame grabber for converting the video signal output into a digital video image;
(c) a processing system for analyzing the digital video image, the processing system performing the following steps;
(1) dividing the digital video image into a plurality of slots, each slot approximately the size of a person within the digital video image;
(2) generating an image difference for each slot;
(3) determining from the image difference whether a slot is occupied by a person; and
(4) determining whether a person overlaps adjacent slots, if it is determined that neither adjacent slot is occupied by a person, by defining a slot overlapping the adjacent slots and detecting whether the overlapping slot is occupied by a person. - View Dependent Claims (2, 3, 4, 5, 6)
(5) updating the background image associated with the video image.
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6. A system according to claim 1, wherein the system eliminates spurious events generated from a customer walking through a queue without stopping by filtering out temporary changes in the state of the queue.
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7. A system for detecting persons standing in a queue, comprising:
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(a) a video camera positioned to view a selected area of interest, the video camera providing a video signal output;
(b) a frame grabber for converting the video signal output into a digital video image;
(c) a processing system for analyzing the digital video image, the processing system performing the following steps;
(1) extracting a region of interest from the video image;
(2) generating an image difference by subtracting the value of each pixel in a background image associated with the extracted region of interest from its associated pixel in the extracted region of interest, and assigning a value of 1 for each difference that exceeds or is equal to a difference threshold and assigning a value of 0 for each difference that is less than the difference threshold;
(3) detecting the presence of edges in the region of interest;
(4) setting all detected edges to 0;
(5) performing a region labeling ope ration on the image difference in order to group adjacent pixels with a value of 1 into objects; and
(6) counting the number of objects to determine the number of persons in the region of interest. - View Dependent Claims (8, 9)
(7) updating the background image associated with the video image.
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9. A system according to claim 8, wherein in step (7) the whole background of the region of interest is updated.
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10. A method for detecting persons standing in a queue, comprising the following steps:
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(a) positioning a video camera to view a selected area of interest to provide a video signal output;
(b) converting the video signal output into a digital video image;
(c) dividing the digital video image into a plurality of slots, each slot approximately the size of a person within the digital video image;
(d) generating an image difference for each slot;
(e) determining from the image difference whether a slot is occupied by a person; and
(f) determining whether a person overlaps first and second adjacent slots, if it is determined that neither adjacent slot is occupied by a person, by defining a slot overlapping the adjacent slots and detecting whether the overlapping slot is occupied by a person.
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11. A method for detecting persons standing in a queue, comprising the following steps:
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(a) positioning a video camera to view a selected area of interest, the video camera providing a video signal output;
(b) converting the video signal output into a digital video image;
(c) extracting a region of interest from the video image;
(d) generating an image difference by subtracting the value of each pixel in a background image associated with the extracted region of interest from its associated pixel in the extracted region of interest, and assigning a value of 1 for each difference that exceeds or is equal to a difference threshold and assigning a value of 0 for each difference that is less than the difference threshold;
(e) detecting the presence of edges in the region of interest;
(f) setting all detected edges to 0;
(g) performing a region labeling operation on the image difference in order to group adjacent pixels with a value of 1 into objects; and
(h) counting the number of objects to determine the number of persons in the region of interest.
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12. A method for detecting persons standing in a queue, comprising the following steps:
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(a) positioning a video camera to view a selected area of interest to provide a video signal output;
(b) converting the video signal output into a digital video image;
(c) dividing the digital video image into a plurality of slots, each slot approximately the size of a person within the digital video image;
(d) generating an image difference for each slot;
(e) determining from the image difference whether a slot is occupied by a person; and
(f) determining whether a person overlaps first and second adjacent slots by;
(1) determining whether either adjacent slot is occupied by a person;
(2) defining an overlapping slot comprising adjacent halves of each of the adjacent slots if it is determined that neither adjacent slot is occupied by a person; and
(3) detecting whether the overlapping slot is occupied by a person.
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13. A method for detecting persons standing in a queue, comprising the following steps:
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(a) positioning a video camera to view a selected area of interest, the video camera providing a video signal output;
(b) converting the video signal output into a digital video image;
(c) extracting a region of interest from the video image;
(d) generating an image difference by subtracting the value of each pixel in a background image associated with the extracted region of interest from its associated pixel in the extracted region of interest, and assigning a value of I for each difference that exceeds or is equal to a difference threshold and assigning a value of 0 for each difference that is less than the difference threshold;
(e) detecting the presence of edges in the region of interest by computing a gradient between adjacent pixels and determining whether the gradient exceeds an edge difference threshold;
(f) setting all detected edges to 0;
(g) performing a region labeling operation on the image difference in order to group adjacent pixels with a value of 1 into objects; and
(h) counting the number of objects to determine the number of persons in the interest.
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Specification