Moving-target tracking apparatus

• US 6,031,568 A
• Filed: 02/02/1998
• Issued: 02/29/2000
• Est. Priority Date: 09/11/1997
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Wakitani, Jun
• Primary Examiner(s): Le, Vu
• Application Number:
  US09/017,313
• Time in Patent Office: 757 Days
• Field of Search: 348/169, 348/170, 348/171, 348/172, 348/214, 348/219-220, 348/143, 348/148, 348/149, 348/154-155, 348/157-158, 348/699-700, 382/103
• US Class Current: 348/169
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51

Abstract

In a moving-target tracking apparatus for tracking a target moving in a dynamic picture image, color information, differential information and target position information based on a prediction for a motion according to the past motion are detected in the form of two-dimensional map. These maps are merged into a single map. A target position is detected in accordance with the merged map. Thus, an operational ability on a real-time basis and a tracking performance are improved.

Claims

1. A moving-target tracking apparatus wherein an original picture image, which consists of a plurality of frames sequentially continued, photographed with a scene including at least one moving object, is inputted and a moving-target selected from among moving objects projected on the original picture image is tracked, said moving-target tracking apparatus comprising:

a first correlation value distribution operational unit for determining a distribution of a first correlation value between a color template to be compared with the moving-target projected on a color separation image constituting the original picture image, and the color separation image;

a differential processing unit for spatially differentiating the original picture image to determine a differential image;

a second correlation value distribution operational unit for determining a distribution of a second correlation value between a differential template to be compared with the moving-target projected on the differential image, and the differential image;

a motion prediction value distribution operational unit for determining a distribution of a motion prediction value representative of a probability of existence of the moving-target in accordance with a past motion of the moving-target;

an evaluation value distribution operational unit for determining an evaluation value through merging the first correlation value, the second correlation value and the motion prediction value to determine a distribution of the evaluation value representative of an existing position of the moving-target; and

a position detecting unit for detecting the existing position of the moving-target in accordance with the distribution of the evaluation value determined in said evaluation value distribution operational unit.

2. A moving-target tracking apparatus according to claim 1, wherein said evaluation value distribution operational unit includes a reliability evaluation unit for evaluating a reliability of the distribution of the first correlation value, and determines the distribution of the evaluation value upon eliminating the distribution of the first correlation value, which is evaluated as low in the reliability, from a processing for determining the distribution of the evaluation value.

3. A moving-target tracking apparatus according to claim 1, wherein said evaluation value distribution operational unit includes a reliability evaluation unit for evaluating a reliability of the distribution of the first correlation value and a reliability of the distribution of the second correlation value, and determines the distribution of the evaluation value upon eliminating the distribution of the first correlation value, which is evaluated as low in the reliability, and the distribution of the second correlation value, which is evaluated as low in the reliability, from a processing for determining the distribution of the evaluation value.

4. A moving-target tracking apparatus according to claim 1, wherein said color template includes a temporary template to be sequentially renewed, and said moving-target tracking apparatus further comprises a color template renewal unit for merging an image area on the color separation image, including the existing position of the moving-target detected by said position detecting unit, with the temporary template to renew the temporary template.

5. A moving-target tracking apparatus according to claim 4, wherein said evaluation value distribution operational unit comprises:

a first merge application unit for determining a merge correlation value for each pixel through merging the first correlation value with the second correlation value for each pixel to determine a distribution of the merge correlation value; and

a second merge application unit for determining an evaluation value for each pixel through merging the merge correlation value determined in said first merge application unit with the motion prediction value determined in said motion prediction value distribution operational unit for each pixel to determine the distribution of the evaluation value, and

wherein said color template renewal unit comprises;

an approximation object detecting unit for detecting existing positions of an approximation object approximated to the moving-target in accordance with the merge correlation value; and

an evaluation/merger unit for renewing the temporary template in such a manner that a first approximation degree representative of an extent of an approximation between a first image area on the color separation image, including the existing position of the moving-target detected by said position detecting unit, and the temporary template, and a second approximation degree representative of an extent of an approximation between the first image area and a second image area including an existing position of the approximation object detected by said approximation object detecting unit, are detected, and in the event that the first approximation degree is larger than the second approximation degree, the first image area is merged with the temporary template.

6. A moving-target tracking apparatus according to claim 1, further comprising a correlator for determining a correlation value integrating the absolute value of difference of pixel values assigned to mutually associated pixels of two images or image areas, throughout the two images or image areas, said correlator being used on a common basis for said first correlation value distribution operation unit and said second correlation value distribution operation unit, alternatively, being individually provided for each of said first correlation value distribution operation unit and said second correlation value distribution operation unit,

wherein said differential processing unit causes said correlator to take a partial charge of a differential operation of differentiating the original picture image to determine the differential image.

7. A moving-target tracking apparatus according to claim 1, wherein said motion prediction value distribution operational unit determines a prediction motion vector predicting a motion of the moving-target from a present instant to a next instant, and provides such a processing that a prediction value, which indicates a maximum probability at an existence prediction position of the moving-target at the next position represented by the prediction motion vector, and a probability which is lowered with further distances from the existence prediction position, is associated with each of pixels on a search area.

8. A moving-target tracking apparatus according to claim 7, wherein said motion prediction value distribution operational unit determines a prediction motion vector predicting a motion of the moving-target from a present instant to a next instant in accordance with the prediction motion vector determined at a past instant, which is representative of the existing prediction position of the moving-target at the present instance, and a motion vector representative of an actual motion of the moving-target, which is determined based on a difference between existence positions of the moving-target detected by said position detecting unit at both the past instant and the present instant.

9. A moving-target tracking apparatus according to claim 7, wherein said motion prediction value distribution operational unit provides such a processing that a motion prediction value, which is given as a function of a distance on the existence prediction position of the moving-target represented by said prediction motion vector, is associated with each of pixels on the search area.

10. A moving-target tracking apparatus according to claim 7, wherein said motion prediction value distribution operational unit provides such a processing that a motion prediction value, having two types of weight in which weight for a distance in a direction of the prediction motion vector is different from weight for a distance in a direction intersecting the direction of the prediction motion vector, said motion prediction value being given in form of a function of said two distances, is associated with each of pixels on the search area.

11. A moving-target tracking apparatus according to claim 7, wherein said motion prediction value distribution operational unit provides such a processing that a motion prediction value, given in form of a function in which a magnitude of the prediction motion vector is a variable, is associated with each of pixels on the search area.

12. A moving-target tracking apparatus according to claim 1, wherein said second correlation value distribution operational unit sets up as the differential template a predetermined image area on a differential image, including a predetermined position on the differential image, which is identical with a predetermined position on the original picture image designated prior to tracking the moving-target.

13. A moving-target tracking apparatus according to claim 12, wherein said color template includes a fixed template, and said first correlation value distribution operational unit sets up as the fixed template an image area on the color separation image, which is detected by said position detecting unit at an instant when the differential template is set up or finally renewed, the image area including an existence position of the moving-target.

14. A moving-target tracking apparatus according to claim 1, wherein said second correlation value distribution operational unit detects a segment area on an image area having a size larger than a size of a differential template, on a differential image, said image area including a predetermined position on the differential image, which is identical with a predetermined position on the original picture image designated prior to tracking the moving-target, said segment area being high in a degree of approximation to a common template set up on a common basis to moving objects capable of being designated as the moving-target, and having a same size as the differential template, and sets up said segment area as the differential template.

15. A moving-target tracking apparatus according to claim 14, wherein said second correlation value distribution operational unit comprises a differential template renewal unit for merging with the differential template image areas on the differential image, which are detected by said position detecting unit at one or more instants after the differential template is set up first, each of the image areas including an existence position of the moving-target, to renew the differential template, said differential template renewal unit being operative at a predetermined initial stage after an initiation of tracking of the moving-target.

16. A moving-target tracking apparatus according to claim 15, wherein said color template includes a fixed template, and said first correlation value distribution operational unit sets up as the fixed template an image area on the color separation image, which is detected by said position detecting unit at an instant when the differential template is set up or finally renewed, the image area including an existence position of the moving-target.

17. A moving-target tracking apparatus according to claim 14, wherein said color template includes a fixed template, and said first correlation value distribution operational unit sets up as the fixed template an image area on the color separation image, which is detected by said position detecting unit at an instant when the differential template is set up or finally renewed, the image area including an existence position of the moving-target.