Image detecting method, image detecting system, program, and recording medium for image detection

• US 6,862,370 B2
• Filed: 05/16/2001
• Issued: 03/01/2005
• Est. Priority Date: 05/19/2000
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Kawano, Miwa, Yamagata, Hideaki, Miyazawa, Toshio, Shimura, Hiroshi, Tachikawa, Michiyoshi
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): SHERALI, ISHRAT I
• Application Number:
  US09/855,665
• Publication Number:
  US 20020006223A1
• Time in Patent Office: 1,385 Days
• Field of Search: 382/199, 382/203, 382/204, 382/117, 382/118, 382/151, 382/152, 382/106, 382181-190, 382/206, 382/209, 382/217, 382/219, 382136-137, 382/276, 382286-297, 382/176, 382/305, 340/988, 707 1- 6, 707/104.1, 731/04
• US Class Current: 382/199
• CPC Class Codes: G06V 10/44 Local feature extraction by analysis of parts of the pattern, e.g. by detecting edges, contours, loops, corners, strokes or intersections; Connectivity analysis, e.g. of connected components

Abstract

An image detecting method comprises the steps of: a) searching for a pattern satisfying a predetermined commencement requirement by scanning an input image; b) using the pattern as a starting point, with referring to a dictionary storing therein distances between the center line and an edge of a detection target semicircle, determining for each of a predetermined number of main scan lines along a sub-scan direction whether or not a predetermined edge pattern occurs within a respective range of the distance of the dictionary; and c) determining a detection of the semicircle when the number of error lines on which the predetermined edge pattern does not occur within the respective range of the distance of the dictionary is less than a predetermined threshold.

Claims

1. An image detecting method comprising the steps of:

a) searching for a pattern satisfying a predetermined commencement requirement by scanning an input image;

b) using the pattern as a starting point, with referring to a dictionary storing therein distances between a center line and an edge of a detection-target semicircle, determining for each of a predetermined number of main scan lines along a sub-scan direction whether or not a predetermined edge pattern occurs within a respective range of a distance in said dictionary, wherein each main scan line not satisfying the range according to the dictionary is counted as an error; and

c) determining a detection of the semicircle when the number of errors is less than a predetermined threshold.

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

the predetermined commencement requirement comprises requirements in which a ratio of black pixels occurring on a current main scan line between predetermined edge patterns is more than a predetermined value, and, also, a ratio of white pixels at the same positions but on an immediately preceding main scan line is more than a predetermined value.

3. The method as claimed in claim 1, wherein:

the number of errors comprises any one of the predetermined main scan lines on which a predetermined left or right edge pattern does not occur, a number of successive main scan lines on which the predetermined left edge pattern does not occur, and the number of successive main scan lines on which the predetermined right edge pattern does not occur.

4. An image detecting system comprising:

a part searching for a pattern satisfying a predetermined commencement requirement by scanning an input image;

a part using the pattern as a starting point, with referring to a dictionary storing therein distances between a center line and an edge of a detection-target semicircle, determining for each of a predetermined number of main scan lines along a sub-scan direction whether or not a predetermined edge pattern occurs within a respective range of a distance in said dictionary, wherein each main scan line not satisfying the range according to the dictionary is counted as an error; and

a part determining a detection of the semicircle when the number of errors is less than a predetermined threshold.

5. The system as claimed in claim 4, wherein:

the predetermined commencement requirement comprises requirements in which a ratio of black pixels occurring on a current main scan line between predetermined edge patterns is more than a predetermined value, and, also, a ratio of white pixels at the same positions but on an immediately preceding main scan line is more than a predetermined value.

6. The system as claimed in claim 4, wherein:

the number of errors comprises any one of the predetermined main scan lines on which a predetermined left or right edge pattern does not occur, a number of successive main scan lines on which the predetermined left edge pattern does not occur, and the number of successive main scan lines on which the predetermined right edge pattern does not occur.

7. A computer-readable recording medium storing therein a program, read by a computer, which thus executes the program so as to perform a process of detecting a predetermined figure, said program comprising:

first program code means for searching for a pattern satisfying a predetermined commencement requirement by scanning an input image;

second program code means for using the pattern as a starting point, with referring to a dictionary storing therein distances between a center line and an edge of a detection-target semicircle, determining for each of a predetermined number of main scan lines along a sub-scan direction whether or not a predetermined edge pattern occurs within a respective range of a distance in said dictionary, wherein each main scan line not satisfying the range according to the dictionary is counted as an error; and

third program code means for determining a detection of the semicircle when the number of errors is less than a predetermined threshold.

8. The recording medium as claimed in claim 7, wherein

the predetermined commencement requirement comprises requirements in which a ratio of black pixels occurring on a current main scan line between

predetermined edge patterns is more than a predetermined value, and, also, a ratio of white pixels at the same positions but on an immediately preceding main scan line is more than a predetermined value.

9. The recording medium as claimed in claim 7, wherein:

the number of errors comprises any one of the predetermined main scan lines on which a predetermined left or right edge pattern does not occur,

the number of successive main scan lines on which a predetermined left edge pattern does not occur, and the number of successive main scan lines on which the predetermined right edge pattern does not occur.