Apparatus and method of tracking an image-feature using a block matching algorithm

• US 5,946,041 A
• Filed: 07/24/1996
• Issued: 08/31/1999
• Est. Priority Date: 01/31/1996
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Morita, Toshihiko
• Primary Examiner(s): LEE, RICHARD J
• Application Number:
  US08/685,494
• Time in Patent Office: 1,133 Days
• Field of Search: 348/384, 348/390, 348/402, 348/407, 348/413, 348/416, 348/420, 348/699, 348/700
• US Class Current: 348/416.1
• CPC Class Codes: H04N 19/54 using feature points or meshes

Abstract

An image-feature tracking apparatus for tracking an object includes a feature deriving part for deriving at least one feature in an image of the object, and a matching operation part for matching two frames of the image defined at different times in the image of the object and producing an approximate motion vector of the feature. The apparatus further includes a motion-vector correcting part for correcting the approximate motion vector provided in the matching operation part based on a position of the feature derived in the feature deriving part. In the image-feature tracking apparatus, from a corrected motion vector provided in the motion-vector correcting part, a position of the object is detected.

Claims

1. An image-feature tracking apparatus for tracking an object, comprising:

feature deriving means for deriving a feature in an image of the object;

matching operation means for matching two frames of said image defmed at different times in said image and producing an approximate motion vector of said feature indicating a motion of said feature; and

motion-vector correcting means for correcting said approximate motion vector produced by said matching operation means based on a value of said approximate motion vector and a position of said feature derived by said feature deriving means, and producing a corresponding corrected motion vector which is dynamically corrected in vertical and horizontal directions;

wherein a position of said object is detected from the corrected motion vector produced by the motion-vector correcting means.

2. The apparatus as claimed in claim 1, wherein:

said matching operation means comprises

means for calculating block matching of a first block image and a second block image in said two frames, and

means for calculating a position of said feature in said second block image where said block matching is maximum and producing the position of the feature as said approximate motion vector; and

said motion-vector correcting means comprises means for correcting said approximate motion vector by adding a deviation between positions of the feature in said two frames to said approximate motion vector.

3. The apparatus as claimed in claim 1, further comprising an imaging device which images said object and provides an image of said object to said matching operation means and said feature deriving means.

4. The apparatus as claimed in claim 1, wherein

said motion-vector correcting means produces a plurality of motion vectors, and

the apparatus further comprises

means for calculating a center position of a plurality of features in said image based on said plurality of motion vectors produced by said motion-vector correcting means, and movement of said object is calculated by using said center position of said plurality of features as a representative position of said object.

5. The apparatus as claimed in claim 4, further comprising means for calculating a degree of rotation, expansion, and contraction of said object based on said plurality of motion vectors produced by said motion-vector correcting means.

6. The apparatus as claimed in claim 4, further comprising:

means for changing image resolution of said object; and

means for averaging a plurality of said representative positions of said object provided for a plurality of image resolutions.

7. An image-feature tracking method for tracking an object, comprising the steps of:

(a) deriving a feature in an image of said object;

(b) matching two frames of said image defmed at different times in said image and producing an approximate motion vector of said feature indicating a motion of said feature; and

(c) correcting said approximate motion vector provided in said step (b) based on a value of said approximate motion vector and a position of said feature derived in said step (a), to produce a corresponding corrected motion vector which is dynamically corrected in vertical and horizontal directions;

wherein a position of said object is detected from said corrected motion vector produced in said step (c).

8. An apparatus for processing an image of an object, the image including first and second frames at first and second times, respectively, the apparatus comprising:

a feature deriving unit which derives a feature of the object from the second frame of the image;

a matching operation unit which matches the first and second frames to produce an approximate motion vector of the feature, indicating a motion of said feature, derived by the feature deriving unit; and

a motion-vector correcting unit which corrects the approximate motion vector produced by the matching operation unit based on a value of said approximate motion vector and a position of the feature derived by said feature deriving unit to produce a corresponding corrected motion vector which is dynamically corrected in the vertical and horizontal directions.

9. The apparatus as in claim 8, wherein the matching operation unit determines the approximate motion vector by performing block matching for first and second block images of the first and second frames, respectively.

10. The apparatus as in claim 8, further comprising:

an imaging device which produces the image of the object and provides the image of the matching operation unit and the feature deriving unit.

11. The apparatus as claimed in claim 8, wherein

the motion-vector correcting unit produces a plurality of motion vectors,

the feature deriving unit derives a plurality of features of the image, and

the apparatus further comprises

a center position unit which calculates a center position of the plurality of features derived by the feature deriving unit based on the plurality of motion vectors produced by the motion-vector correcting unit, and

movement of the object is calculated from the center position of the plurality of features as a representative position of the object.

12. A method for processing an image of an object, the image including first and second frames at first and second times, respectively, the method comprising the steps of:

deriving a feature of the object from the second frame of the image;

matching the first and second frames to produce an approximate motion vector of the derived feature which indicates a motion of the feature; and

correcting the approximate motion vector based on a value of said approximate motion vector and a position of the derived feature to produce a corresponding motion vector which is dynamically corrected in the vertical and horizontal directions.