METHOD AND APPARATUS FOR CHARACTER STRING RECOGNITION

• US 20080304746A1
• Filed: 04/28/2008
• Published: 12/11/2008
• Est. Priority Date: 04/27/2007
• Status: Active Grant

• Current Assignee: Nidec Sankyo Corporation (Nidec Corporation)
• Original Assignee: Nidec Sankyo Corporation (Nidec Corporation)
• Inventors: Nakamura, Hiroshi
• Granted Patent: US 8,200,016 B2
• Time in Patent Office: Days
• US Class Current: 382/177
• CPC Class Codes: G06V 30/10 Character recognition
• CPC Class Codes: G06V 30/158 using character size, text spacings or pitch estimation

Abstract

To provide a method and apparatus for character string recognition that enables improvement in accuracy of character recognition while maintaining high-speed operation performance in character recognition.

Claims

1. A method for character string recognition by processing image data obtained through picking up a character string placed on a medium comprising:

a first step of processing the image data into black-and-white binary image data by using a prescribed reference threshold value for binary conversion;

a second step of calculating vertical projection data of the binary image data in a vertical direction perpendicular to a direction of the character string while shifting the binary image data in the direction of the character string;

a third step of detecting positions exceeding a prescribed border judgment threshold value in the vertical projection data obtained through the second step described above as segmentation positions of characters included in the character string; and

a fourth step of segmenting the characters out of the character string according to the segmentation positions of the characters detected through the third step, and examining characteristics of each character segmented; and

further comprising;

a fifth step of judging validity of the border judgment threshold value before the fourth step according to the number of characters included in the character string.

2. The method for character string recognition according to claim 1:

wherein the reference threshold value for binary conversion is changed when the border judgment threshold value is judged to be invalid by the fifth step, and the image data is processed again into binary image data, and then the first step through the fifth step are carried out again.

3. The method for character string recognition according to claim 2:

wherein the reference threshold value for binary conversion is changed to be smaller than the initial one when the border judgment threshold value is judged to be invalid by the fifth step.

4. The method for character string recognition according to claim 1:

wherein the prescribed border judgment threshold value corresponds to the “

n+1”

-th value of the peak values where the positive peak values included in the vertical projection data are disposed in due order starting from the largest one and the “

n”

represents the number of characters included in the character string.

5. An apparatus for character string recognition comprising:

means for recognizing a character string placed on a medium by using the method for character string recognition in accordance with claim 1.

6. The method for character string recognition according to claim 2:

wherein the prescribed border judgment threshold value corresponds to the “

n+1”

-th value of the peak values where the positive peak values included in the vertical projection data are disposed in due order starting from the largest one and the “

n”

represents the number of characters included in the character string.

7. The method for character string recognition according to claim 3:

wherein the prescribed border judgment threshold value corresponds to the “

n+1”

-th value of the peak values where the positive peak values included in the vertical projection data are disposed in due order starting from the largest one and the “

n”

represents the number of characters included in the character string.

8. An apparatus for character string recognition comprising:

means for recognizing a character string placed on a medium by using the method for character string recognition in accordance with claim 2.

9. An apparatus for character string recognition comprising:

means for recognizing a character string placed on a medium by using the method for character string recognition in accordance with claim 3.

10. An apparatus for character string recognition comprising:

means for recognizing a character string placed on a medium by using the method for character string recognition in accordance with claim 4.