System and method for monitoring visible changes

• US 6,335,976 B1
• Filed: 02/26/1999
• Issued: 01/01/2002
• Est. Priority Date: 02/26/1999
• Status: Expired due to Fees

• Current Assignee: Bomarc Surveillance Incorporated
• Original Assignee: Bomarc Surveillance Incorporated
• Inventors: Belmares, Robert J.
• Primary Examiner(s): Patel, Jayanti K.
• Application Number:
  US09/258,056
• Time in Patent Office: 1,040 Days
• Field of Search: 382/100, 382/236, 382/173, 382/103, 382/171, 382/172, 382/209, 382/217, 382/218, 382/232, 382/238, 382/239, 382/255, 382/274, 250/201.9, 250/204, 250/559.04, 348/152-155, 345/473, 345/474
• US Class Current: 382/103
• CPC Class Codes: G06T 7/254 involving subtraction of images
• CPC Class Codes: G08B 13/19602 Image analysis to detect motion of the intruder, e.g. by frame subtraction
• CPC Class Codes: G08B 13/19606 Discriminating between target movement or movement in an area of interest and other non-signicative movements, e.g. target movements induced by camera shake or movements of pets, falling leaves, rotating fan

Abstract

A method for monitoring a field of view for visible changes is disclosed. A first image is taken in a predetermined manner of the field of view to be monitored, and then an array divides the first image into a plurality of cells. A second image is taken in the predetermined manner of the field of view to be monitored. The array is also applied to the second image, dividing the second image into the plurality of cells. Predetermined groups of cells of the second image are then compared to the same groups of cells of the first image, and the number of the groups of cells that changed from the first image to the second image is computed. In some situations only certain groups of cells are compared. In one form of the method, each cell of the first image is given a numerical value based upon the information in each cell, and each cell of the second image is also given a numerical value based upon the information in each cell. Each group of cells is also given a numerical value based on the numerical value of the cells within the group, such as the sum of the numerical values of the cells within the group. In one arrangement, each cell is a single picture element, known as a pixel. The numerical value of each group of cells is the sum of the brightness for the pixels in the group. In one such arrangement, the predetermined groups of cells comprises a single group. In one method, the number of the groups of cells which changed in numerical value by more than a predetermined amount is also computed.

Claims

1. A method for monitoring a field of view for visible changes, comprising in combination the steps of:

taking a first image in a predetermined manner of the field of view to be monitored;

dividing the first image into a plurality of cells;

taking a second image in the predetermined manner of the field of view to be monitored after creating the first image;

dividing the second image into the plurality of cells;

comparing predetermined groups of cells of the second image to the same predetermined groups of cells of the first image;

giving each cell of the first image a numerical value based upon the information in each cell;

giving each cell of the second image a numerical value based upon the information in each cell;

giving each group of cells a numerical value based upon the numerical value of the cells within that group; and

wherein comparing predetermined groups of cells of the second image to the same predetermined groups of cells in the first image comprises computing the difference between the numerical values of each group of cells in the second image and in the first image.

2. A method according to claim 1 wherein:

each cell comprises a pixel; and

the numerical value of each cell comprises the brightness of the pixel.

3. A method according to claim 2 wherein the numerical value of each group of cells comprises the sum of the brightness for the pixels in the group.

4. A method according to claim 3 wherein the predetermined groups of cells comprises a single group.

5. A method for monitoring a field of view for visible changes, comprising in combination the steps of:

taking a first image in a predetermined manner of the field of view to be monitored;

dividing the first image into a plurality of areas;

taking a second image in the predetermined manner of the field of view to be monitored after creating the first image;

dividing the second image into the plurality of areas;

comparing predetermined areas of the second image to the same areas of the first image;

computing the number of the predetermined areas that changed from the first image to the second image;

dividing each area of the first image a numerical value based upon the information in each area;

giving each area of thief second image a numerical value based upon the information in each area; and

wherein computing the number of the predetermined areas that changed from the first image to the second image comprises computing the difference between the numerical values of each area in the second image and in the first image.

6. A method according to claim 5 further comprising the step of computing the number of the predetermined areas that changed in numerical value by more than a predetermined amount.

7. A method according to claim 5 further comprising the step of computing the number of the predetermined areas that changed in numerical value by more than a predetermined amount.

8. A method according to claim 7 further comprising the step of comparing the number of the predetermined areas that changed from the first image to the second image to a predetermined number.

9. A method according to claim 8, further comprising the steps of:

giving each area of the first image a numerical value based upon the information in each area;

giving each area of the second image a numerical value based upon the information in each area; and

wherein computing the number of the predetermined areas that changed from the first image to the second image comprises computing the difference between the numerical values of each areas in the second image and in the first image.

10. A method according to claim 9 further comprising the step of computing the number of the predetermined areas that changed in numerical value by more than a predetermined amount.

11. A method for monitoring a field of view for visible changes, comprising in combination the steps of:

taking a sequence of images in a predetermined manner of the field of view to be monitored;

dividing each of the images into an identical plurality of areas;

comparing a plurality of predetermined areas of each image to the same areas of the other images;

computing if there is a cyclical change in any of the predetermined areas during the sequence;

giving each area of each image a numerical value based upon the information in that area; and

wherein computing if there is a cyclical change in any of the predetermined areas during the sequence comprises computing if there is a cyclical change in any of the numerical values of the predetermined areas during the sequence.

12. A method according to claim 11, further comprising the step of computing the number of the predetermined areas that changed from one image of the sequence to the next image of the sequence and was not part of a cyclical change.

13. A method according to claim 11, further comprising the step of computing the number of the predetermined areas that changed from one image of the sequence to the next image of the sequence and was not part of a cyclical change.

14. A method for monitoring a field of view for visible changes, comprising in combination the steps of:

taking a sequence of images in a predetermined manner of the field of view to be monitored;

dividing each of the images into a plurality of cells;

comparing a plurality of predetermined groups of cells of each image to the same groups of cells of the other images;

computing if there is a cyclical chance in any of the predetermined groups of cells during the sequence;

giving each cell of each image a numerical value based upon the information ill that cell;

giving each group of cells of each image a numerical value based upon the numerical value of the cells within that group; and

wherein computing ii there is a cyclical chance in any of the predetermined groups of cells during the sequence comprises computing if there is a cyclical change in any of the numerical values of the predetermined groups of cells during the sequence.

15. A method according to claim 14, wherein:

each cell comprises a pixel;

the numerical value of each cell comprises the brightness of the pixel; and

the numerical value of each group of cells comprises the slum of the brightness

for the pixels in the group.

16. A method according to claim 15, wherein the predetermined groups of cells comprises a single group.