Method of detecting an object's motion by a digital camera

• US 6,954,226 B2
• Filed: 11/19/2001
• Issued: 10/11/2005
• Est. Priority Date: 11/22/2000
• Status: Expired due to Fees

• Current Assignee: Advmatch Technology Incorporated
• Original Assignee: Elecvision Incorporated
• Inventors: Hsiao, Yuan-Jen, Hsieh, Chun-Hsing
• Primary Examiner(s): Vu, Ngoc-Yen, Vu, Ngoc-Yen
• Assistant Examiner(s): Lam, Hung H
• Application Number:
  US09/988,375
• Publication Number:
  US 20020060737A1
• Time in Patent Office: 1,422 Days
• Field of Search: 348/155, 348/254, 348/208.1, 348/152, 348/169, 348/153, 348/154
• US Class Current: 348/208.1
• 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 13/1968 Interfaces for setting up or customising the system
• CPC Class Codes: H04N 5/144 Movement detection for video coding H04N19/503; analysis of motion in general G06T7/20

Abstract

A method of detecting motion is described. A first image is captured and exposed by a digital camera. The first image information is transferred to a control device. Gray level values of a specific group in the first image are then stored. Real-time gray level values corresponding to the specific group in a real time image are subsequently captured. The real-time gray level values of the specific group in a real time image are compared with the gray level values of the specific group in the first image. An amount of specific points with different gray level between the specific groups in the real-time image and the first image greater than N indicates an object of the real-time image is in motion or else the object of the real-time image is motionless. A sequential step for the object detected to be in motion is then performed. The real-time gray level values of the specific group in the real-time image are stored as the gray level values of the specific group in the first image.

Claims

1. A method of detecting motion for digital camera, said method comprising the steps of:

storing gray level values of a specific group in a first image;

capturing real-time gray level values corresponding to said specific group in a real-time image;

comparing said real-time gray level values of said specific group in said real-time image with said gray level values of said specific group in said first image;

determining whether gray level differences between said specific groups in said real-time image and said first image are greater than a predetermined threshold value, wherein said gray level differences greater than said threshold value indicate an object of said real-time image is in motion or else no motion is occurring in the real-time image;

performing a sequential step for the object detected to be in motion when said gray level value differences are greater than said threshold value;

storing said real-time gray level values of said specific group in said real-time image as said gray level values of said specific group in said first image;

setting a parameter F equal to 1 when the object of said real-time image is determined to be in motion;

setting said parameter F equal to 0 when the object of said real-time image is determined to be motionless;

checking said parameter F;

sequentially performing the motion detection steps when said parameter F is equal to 0; and

stopping motion detection steps for a predetermined time when said parameter F is equal to 1 and resetting said parameter F equal to 0 to continue the motion detection steps.

2. The method according to claim 1, wherein said specific group substantially includes one or a plurality of specific points selected from said images.

3. The method according to claim 2, wherein said specific points are uniformly distributed over entire image.

4. The method according to claim 2, wherein said specific points are partially concentrated on a central portion of entire image for enhancing detecting efficiency of the central portion of entire image.

5. The method according to claim 2, wherein an amount of said specific points is adjustable depending on the detecting efficiency.

6. The method according to claim 1, wherein the step of determining whether gray level differences between said specific groups in said real-time image and said first image are greater than a predetermined threshold value further comprises:

subtracting said gray level values of said specific group in said first image from said real-time gray level values of said specific group in said real-time image to generate a plurality of gray level differences of said corresponding specific groups; and

determining whether said gray level differences are greater than said predetermined threshold value;

wherein any one of said gray level differences being greater than said predetermined threshold value indicates the object of said real-time image is in motion.

7. The method according to claim 6, wherein said threshold value is adjustable for changing a detection sensitivity of the digital camera.

8. The method according to claim 1, wherein said sequential step comprises taking photos, taking a motion picture, sounding an alarm, or flashing a LED light to warn a system operator or a guard.

9. A method of detecting motion for a digital camera, said method comprising the steps of:

storing gray level values of a specific group in a first image;

capturing real-time gray level values corresponding to said specific group in a real-time image;

comparing said real-time gray level values of said specific group in said real-time image with said gray level values of said specific group in said first image;

determining whether an amount of specific points with different gray levels between said specific groups in said real-time image and said first image is greater than N, wherein the amount of specific points with different gray levels greater than N indicates an object of said real-time image is in motion or else no motion in the real-time image;

performing a sequential step for the object detected to be in motion when the amount of specific points with different gray levels is greater than N; and

storing said real-time gray level values of said specific group in said real-time image as said gray level values of said specific group in said first image;

setting a parameter F equal to 1 when the object of said real-time image is determined to be in motion;

setting said parameter F equal to 0 when the object of said real-time image is determined to be motionless;

checking said parameter F;

sequentially performing the motion detection steps when said parameter F is equal to 0; and

Stopping motion detection steps for a predetermined time when said parameter F is equal to 1 and resetting said parameter F equal to 0 to continue the motion detection steps.

10. The method according to claim 9, wherein said specific group substantially includes one or a plurality of said specific points selected from said images.

11. The method according to claim 10, wherein said specific points are uniformly distributed over entire image.

12. The method according to claim 10, wherein said specific points are partially concentrated on a central portion of entire image for enhancing detection efficiency of the central portion of entire image.

13. The method according to claim 10, wherein an amount of said specific points is adjustable depending on the detection efficiency.

14. The method according to claim 9, wherein the step of determining whether an amount of specific points with different gray levels between said specific groups in said real-time image and said first image is greater than N further comprises:

subtracting said gray level values of said specific group in said first image from said real-time gray level values of said specific group in said real-time image to generate a plurality of gray level differences of said corresponding specific groups; and

determining whether an amount of said gray level differences unequal to zero is greater than N;

wherein the amount of said gray level differences unequal to zero being greater than N indicates the object of said real-time image is in motion.

15. The method according to claim 14, wherein N is adjustable for changing a detection sensitivity of the digital camera.

16. The method according to claim 9, wherein said sequential step comprises taking photos, taking a motion picture, sounding an alarm, or flashing a LED light to warn a guard.