Method and apparatus for moving object detection

• US 5,877,804 A
• Filed: 04/06/1995
• Issued: 03/02/1999
• Est. Priority Date: 04/25/1994
• Status: Expired due to Fees

• Current Assignee: Fujikura Limited
• Original Assignee: FMT Corporation Incorporated, Fujikura Limited
• Inventors: Otsuki, Akira, Choi, Yun Jong
• Primary Examiner(s): Chevalier, Robert
• Application Number:
  US08/417,686
• Time in Patent Office: 1,426 Days
• Field of Search: 348/155, 348/152, 348/153, 348/700, 348/143, 382/294, 382/276, 382/107, 382/254, 386/52
• US Class Current: 348/155
• CPC Class Codes: G01S 3/7865 using correlation of the live video image with a stored image
• CPC Class Codes: G08B 13/19602 Image analysis to detect motion of the intruder, e.g. by frame subtraction
• CPC Class Codes: G08B 13/19604 involving reference image or background adaptation with time to compensate for changing conditions, e.g. reference image update on detection of light level change
• CPC Class Codes: G08B 13/19634 Electrical details of the system, e.g. component blocks for carrying out specific functions
• CPC Class Codes: H04N 5/144 Movement detection for video coding H04N19/503; analysis of motion in general G06T7/20

Abstract

The present invention provides a method for detecting a moving object and apparatus for the same. The image data Δ_ij (k)! outputted by subtracter 4 are alternatively contained in image buffers 21 and 22. In subtracter 24, the image data Δ_ij (k-1)! of one timing beforehand is removed from the image data Δ_ij (k)! of the present time point. In addition, the image data Δ_ij (k-1)! of one timing beforehand and the image data Δ_ij (k)! of the present time point are compared using comparator 25. In this case, if image data Δ_ij (k)! and image data Δ_ij (k-1)! differ, the image data Δ_ij (k-1)! of one timing beforehand is supplied to subtracter 26. The initial moving object image is excluded by subtracter 26. Consequently, it is possible to precisely distinguish the shape, size, etc. of a moving object without traces (afterimage) of the moving object at the present time point remaining in the final image data Δ_ij (k)! _R. According to another method also proposed in the present invention, the image data Δ_ij (k-1)! of the moving object are obtained by subtracting the image data D_ij (k-1)! of one timing beforehand or the average image data M_ij (k-1)! of one timing beforehand from the present image data D_ij (k)!, and the image data Δ_ij (k-2)! of the moving object are obtained by subtracting the image data D_ij (k-2)! of two timings beforehand or the average image data M_ij (k-2)! of two timings beforehand from the present image data D_ij (k)!. The traces (afterimage) of a moving object is erased by obtaining theoretical product of the image data Δ_ij (k-1)! and Δ_ij (k-2)!.

Claims

1. Method for detecting a moving object comprising the steps of:

incorporating image data which is sequentially supplied over a predetermined time interval;

accumulating and averaging image data of a predetermined period of the past;

detecting image data of a moving object within said sequentially supplied image data by means of subtracting said averaged image data from said sequentially supplied image data; and

excluding image data corresponding to an afterimage of said moving object by means of subtracting image data of a moving object detected over a predetermined time period of the past from said image data of said detected moving object.

2. Method for detecting a moving object comprising the steps of:

incorporating image data which is sequentially supplied over a predetermined time interval;

accumulating and averaging image data of a predetermined period of the past;

excluding image data corresponding to an afterimage of a moving object at the time of averaging; and

detecting image data of said moving object by means of subtracting said averaged image data in which image data corresponding to said afterimage of said moving object has been excluded from said sequentially supplied image data.

3. A moving object detecting apparatus, comprising:

standard image forming means for incorporating image data which is sequentially supplied over a predetermined time interval, for accumulating and averaging image data of a predetermined period of the past, and for sequentially outputting said accumulated and averaged image data as standard image data;

first subtracting means for detecting image data of a moving object by subtracting said standard image data from said sequentially supplied image data;

storing means for storing image data of a moving object of a predetermined previous time period from among image data of a moving object detected by said first subtracting means; and

second subtracting means for subtracting said image data of said moving object of said predetermined previous time period stored by said storing means from said image data of a moving object detected by said first subtracting means.

4. The moving object detecting apparatus according to claim 3, further comprising:

comparing means for comparing said image data of said moving object of said predetermined previous time period and image data of a moving object at a present time point, and for outputting said image data of said moving object of said predetermined previous time period when image data of said moving object is detected by said comparison; and

initial moving object excluding means for subtracting image data outputted by said comparing means from image data outputted by said second subtracting means.

5. A moving object detecting apparatus, comprising:

standard image forming means for incorporating image data which is sequentially supplied over a predetermined time interval, for accumulating and averaging image data of a predetermined period of the past, and for sequentially outputting said accumulated and averaged image data as standard image data;

storing means for storing standard image data of a moving object of a predetermined previous time period from among standard image data sequentially outputted by said standard image forming means;

first subtracting means for subtracting said standard image data stored in said storing means from said sequentially supplied image data and for outputting image data; and

second subtracting means for subtracting said image data outputted by said first subtracting means from said standard image data sequentially supplied to said standard image forming means.

6. A moving object detecting apparatus for detecting image data of a moving object by subtracting reference image data based on image data of the past from image data of the present, said moving object detecting apparatus comprising:

first and second storing means for respectively storing reference image data, which is image data of the past, based on an image deviating by a fixed amount of time;

first subtracting means for subtracting reference image data stored in said first storing means from said present image data and for outputting a first output;

second subtracting means for subtracting reference image data stored in said second storing means from said present image data and for outputting a second output; and

logical product circuit means for obtaining a logical product of the first and second outputs.

7. The moving object detecting apparatus according to claim 6, wherein said first and second storing means alternatively store reference image data of one cycle previous to a present cycle and reference image data of two cycles previous to said present cycle.

8. The moving object detecting apparatus according to claim 6, wherein said first and second storing means alternatively store standard image data based on image data of 1 to n frames previous to a present frame and standard image data based on image data of n+1 to 2n frames previous to said present frame.

9. A method for detecting a moving object, comprising the steps of:

incorporating image data which is sequentially supplied over a predetermined time interval;

accumulating and averaging image data of a first predetermined period of the past;

detecting image data of said moving object within said sequentially supplied image data by subtracting said averaged image data from said sequentially supplied image data; and

excluding image data corresponding to an afterimage of said moving object by subtracting image data of a moving object detected over a second predetermined period of the past from said detected image data of said moving object.

10. A method for detecting a moving object, comprising the steps of:

incorporating image data which is sequentially supplied over a predetermined time interval;

accumulating and averaging image data of a predetermined period of the past;

excluding image data corresponding to an afterimage of said moving object at the time of averaging; and

detecting image data of said moving object by subtracting said averaged image data, in which image data corresponding to said afterimage of said moving object has been excluded, from said sequentially supplied image data.