Position detection system and method

• US 6,185,343 B1
• Filed: 01/16/1998
• Issued: 02/06/2001
• Est. Priority Date: 01/17/1997
• Status: Expired due to Fees

• Current Assignee: Panasonic Electric Works Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Asahi Matsushita Electric Works Ltd. (Panasonic Holdings Corporation)
• Inventors: Ikeda, Kazutaka, Hashimoto, Yoshihito
• Primary Examiner(s): COUSO, YON JUNG
• Application Number:
  US09/008,077
• Time in Patent Office: 1,117 Days
• Field of Search: 382/291, 382/294, 382/216, 382/227, 382/295-297, 382/217, 382/218
• US Class Current: 382/291
• CPC Class Codes: G06V 10/7515 Shifting the patterns to accommodate for positional errors

Abstract

A position detection system which performs rough detection processing of detecting a rough position of an approximate position of a check object in a check range based on the comparison result of comparison processing of comparing images provided by compressing the check image and a correct solution image subjected to the detection displacement operation of displacing by rough detection displacement amount at a time in the check image, then performs precise detection processing of detecting a more precise position of the check object in the check range in the proximity of the rough position based on the comparison result of comparison processing of comparing images provided by compressing the check image and the correct solution image subjected to the detection displacement operation of displacing by rough detection displacement amount at a time in the check image at a compression rate more moderate than the previous compression rate, and detects the position of the check object in the check range in multiple steps, wherein the compression processing is average compression processing.

Claims

1. A method for detecting a position of a check object using image processing, comprising the steps of:

picking up an image of the check object so as to prepare a check image of the check object;

smoothing said check image of the check object by removing noise associated with said check image;

preparing a reference template having a reference image of the check object;

preparing a plurality of collation templates by rotating the reference template at various rotation angles;

collating the collation templates with the check image so as to evaluate a correlation degree therebetween;

acknowledging a rotation angle of the reference template for preparing the collation template, which matches with the check image most exactly, as a rotation angle of the check object; and

compressing the check image and the collation templates at a given compression rate by an average compression processing which calculates an average value of a brightness in a predetermined area and adopts the average value as a brightness of one pixel of the compressed check image and the collation templates, wherein said predetermined area comprises more than one pixel.

2. The method for detecting a position of a check object according to claim 1, wherein the step for preparing the collation templates is performed using a hardware dedicated to preparation of the collation templates and the collating step is performed using a collation operation section provided separate from the hardware.

3. The method for detecting a position of a check object according to claim 1, wherein the reference template and the collation templates are prepared before the picking-up step.

4. The method for detecting a position of a check object according to claim 1, further comprising the steps of limiting the rotation angle of the reference template for preparing the collation template to a predetermined range.

5. The method for detecting a position of a check object according to claim 1, further comprising the steps of:

finding a rotation angle of a main axis of the check object; and

limiting the rotation angle of the reference template for preparing the collation template to a rotation angle range of the main axis as a center and an angle range different 180 degrees from the rotation angle range of the main axis.

6. The method for detecting a position of a check object according to claim 1, further comprising the steps of:

defining a representative point of the check object; and

matching a center of the collation template with the representative point of the check object so as to evaluate the correlation degree between the check object and the collation templates.

7. The method for detecting a position of a check object according to claim 1, further comprising the steps of:

collating the compressed collation templates with the compressed check image so as to detect a rough rotation angle of the check object;

compressing the check image and the collation templates at a compression rate more moderate than the previous compression rate by the average compression processing after detecting the rough rotation angle;

displacing the compressed collation templates in a proximity of the rough rotation angle;

collating the compressed collation templates with the compressed check image so as to detect a more precise rotation angle than the rough rotation angle of the check object; and

repeating all above steps while moderating the compression rate in multiple steps so as to detect the precise rotation angle of the check object.

8. A method for detecting a position of a check object using image processing, comprising the steps of:

(1) picking up an image of the check object so as to prepare a check image of the check object;

(2) preparing a correct solution image having a reference image of the check object;

(3) compressing the check image and the correct solution image at a given compression rate by an average compression processing which calculates an average value of a brightness in a predetermined area and adopts the average value as a brightness of one pixel of the compressed check image and the compressed correct solution image, wherein said predetermined area comprises more than one pixel;

(4) displacing the compressed correct solution image;

(5) comparing the compressed check image and the compressed/displaced correct solution image so as to detect a rough position of the check object;

(6) compressing the check image and the correct solution image after detecting the rough position at a compression rate more moderate than the previous compression rate by the average compression processing;

(7) displacing the compressed correct solution image in a proximity of the rough position;

(8) comparing the compressed check image and the compressed/displaced correct solution image so as to detect a more precise position than the rough position of the check object; and

(9) repeating (3) to (8) steps while moderating the compression rate in multiple steps so as to detect the precise position of the check object.

9. The method for detecting a position of a check object according to claim 8, further comprising the steps of:

detecting a plurality of the rough positions in the step (5); and

narrowing down the detected rough positions.

10. The method for detecting a position of a check object according to claim 8, wherein a displacement amount in the step (7) is smaller than a displacement amount in the step (4).

11. The method for detecting a position of a check object according to claim 8, wherein the step (4) includes a step of moving the compressed correct solution image according to a raster scanning, and the step (7) includes steps of moving the compressed correct solution image according to the raster scanning and rotating the compressed correct solution image.

12. The method for detecting a position of a check object according to claim 8, wherein the comparing steps includes arithmetic of sum of products executed by calculation means dedicated to execution of aim calculation.

13. A system for detecting a position of a check object using image processing, comprising:

means for picking up an image of the check object so as to prepare a check image of the check object;

means for smoothing said check image of the check object by removing noise associated with said image;

means for preparing a reference template having a reference image of the check object;

means for preparing a plurality of collation templates by rotating the reference template at various rotation angles;

means for collating the collation templates with the check image so as to evaluate a correlation degree therebetween;

means for acknowledging a rotation angle of the reference template for preparing the collation template, which matches with the check image most exactly, as a rotation angle of the check object, and

means for compressing the check image and the collation templates at a given compression rate by an average compression processing which calculates an average value of a brightness in a predetermined area and adopts the average value as a brightness of one pixel of the compressed check image and the collation templates, wherein said predetermined area comprises more than one pixel.

14. The system for detecting a position of a check object according to claim 13, wherein said means for preparing the collation templates includes a hardware dedicated to preparation of the collation templates and said means for collating includes a collation operation section provided separate from said hardware.

15. The system for detecting a position of a check object according to claim 13, wherein the reference template and the collation templates are prepared before picking-up the image of the check object.

16. The system for detecting a position of a check object according to claim 13, further comprising means for limiting the rotation angle of the reference template for preparing the collation template to a predetermined range.

17. The system for detecting a position of a check object according to claim 13, further comprising:

means for finding a rotation angle of a main axis of the check object; and

means for limiting the rotation angle of the reference template for preparing the collation template to a rotation angle range of the main axis as a center and an angle range different 180 degrees from the rotation angle range of the main axis.

18. The system for detecting a position of a check object according to claim 13, further comprising:

means for defining a representative point of the check object; and

mean for matching a center of the collation template with the representative point of the check object so as to evaluate the correlation degree between the check object and the collation templates.

19. The system for detecting a position of a check object according to claim 13, further comprising:

means for collating the compressed collation templates with the compressed check image so as to detect a rough rotation angle of the check object,

wherein said compressing means compresses the check image and the collation templates at a compression rate more moderate than the previous compression rate by the average compression processing after detecting the rough rotation angle,

said collating means collates the compressed collation templates with the compressed check image in a proximity of the rough rotation angle so as to detect a more precise rotation angle than the rough rotation angle of the check object, and

said compressing and collating means repeat compressing and collating steps while moderating the compression rate in multiple steps so as to detect the precise rotation angle of the check object.

20. A system for detecting a position of a check object using image processing, comprising:

means for picking up an image of the check object so as to prepare a check image of the check object;

means for preparing a correct solution image having a reference image of the check object;

means for compressing the check image and the correct solution image at a given compression rate by an average compression processing which calculates an average value of a brightness in a predetermined area and adopts the average value as a brightness of one pixel of the compressed check image and the compressed correct solution image, wherein said predetermined area comprises more than one pixel; and

means for comparing the compressed check image and the compressed correct solution image so as to detect a rough position of the check object,

wherein said compressing means compresses the check image and the correct solution image at a compression rate more moderate than the previous compression rate by the average compression processing after detecting the rough position,

said comparing means compares the compressed correct solution means and the compressed check image in a proximity of the rough position so as to detect a more precise position than the rough position of the check object, and

said compressing and comparing means repeat compressing and comparing steps while moderating the compression rate in multiple steps so as to detect the precise position of the check object.

21. The system for detecting a position of a check object according to claim 20, wherein said comparing means detects a plurality of the rough positions, and the system further comprising means for narrowing down the detected rough positions.

22. The system for detecting a position of a check object according to claim 20, wherein a displacement amount for detecting the rough position is smaller than a displacement amount for detecting the more precise position.

23. The system for detecting a position of a check object according to claim 20, wherein said comparing means compares the compressed correct solution means and the compressed check image by moving the compressed correct solution image according to a raster scanning for detecting the rough position, and by moving the compressed correct solution image according to the raster scanning and rotating the compressed correct solution image for detecting the more precise position.

24. The system for detecting a position of a check object according to claim 20, further comprising means for executing arithmetic of sum of products dedicated to execution of aim calculation.