JPH0117191B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a character recognition method that corrects the reference point of a character pattern when the mask matching method fails to recognize the character and a retry is made.

Conventionally, a mask matching method is used to read and recognize characters printed on a type drum using an optical character reader (OCR). What is the mask matching method? When recognizing characters printed on paper as shown in Figure 1a, the character pattern read by the OCR sensor while feeding the paper in the area of one character (M x N) is the same as shown in Figure 1a. If b, the center of the character is found from the shape of the character pattern. That is, let us find the intersection point ○a of 1/2 each of the left and right width x and the top and bottom height y. The center of this character pattern is aligned with the center of the standard character pattern previously stored in the memory, as shown in FIG. 3c, and the character with the highest degree of overlap becomes the character to be recognized.

Normal characters can be recognized using the method described above, but if there is dirt or dirt attached to the character as shown in the circle (○) in the figure d, or if there is a chip (○) as shown in the figure e, the upper and lower The length of becomes y′, y″ and 1/2 of that
The center determined by this method deviates from the normal center position ○a. Therefore, there may be cases where the mask matching method described above cannot be recognized.

In such cases, no matter how many times you try, the result is the same. Rather, it may be possible to recognize the center by finding the center of the normal case.

SUMMARY OF THE INVENTION An object of the present invention is to provide a character recognition system that corrects the center of the character pattern to the normal center position when a retry is made due to unreadable characters using the mask matching method.

In order to achieve the above object, the character recognition method of the present invention finds a character reference point from the shape of a character pattern read by an optical character reading means, aligns it with the center of a separately stored standard character pattern, and recognizes the character using a mask matching method. When an unrecognized character occurs in a character recognition method and a retry is performed, the reference point of the character pattern is corrected to a position analogous to the reference point of the already recognized character pattern and the retry is performed using the mask matching method. It is characterized by:

The present invention will be described in detail below with reference to examples.

FIG. 2 is a diagram explaining the principle of the present invention.

In the same figure, it is assumed that as a result of reading and recognizing "5", recognition becomes impossible due to the defect shown in FIG. 1d, for example, and a retry is performed. In this case, if the center ○I is determined using the conventional method, it will still be unrecognizable, so in the present invention, it is determined by analogy from the center position of the character "0" immediately above, which has already been recognized.
That is, the left and right sides are the same, and the mask matching method is applied to the top and bottom with a point ○a' shifted downward by the standard pitch Z between character areas as the center. When recognized in this way, even if there is dust or dirt, the matching is within an acceptable range and the characters can be recognized.

FIG. 3 is an explanatory diagram showing the configuration of an embodiment of the present invention according to the above-described principle.

In the same figure, the characters printed on the paper are OCRed.
The data is read by a reading unit 11 such as the above, converted into binary information by an AD conversion unit 12 and a slice circuit, and temporarily stored in a data storage unit 13. This content is read out to the character pattern center detection circuit 14 one area at a time, and the center coordinates obtained from the left and right x and 1/2 up and down y positions of the character pattern based on the character pattern and the above-mentioned method are sent to the comparison circuit 15. , and apply the mask matching method to the center coordinates of each character pattern in the standard pattern table 16. When the degree to which the detected character pattern is masked by the centered standard pattern is greatest and exceeds a certain value, it is recognized (OK), and when this is not satisfied, it is unrecognizable (NG). If recognition is possible (OK), the information is notified to the CPU via the interface 17, and, for example, in the case of a voting ticket refund, a refund process is performed. If it is unrecognizable (NG), send the address and character pattern of the character that has become NG to the character center correction unit 21, and extract the NG character from the storage unit that stores the same character data group as the data in the data storage unit 13. For example, as mentioned above, the center coordinates (x ₁ ,
y ₁ ), x ₁ is left as is, y ₁ is shifted downward by the standard pitch Z, the coordinates (x ₁ , y ₁ + Z) are set as the center of the NG character, and the character pattern is sent to the comparison circuit 15 along with the standard pitch. Apply the mask matching method again to match the center of the pattern and try again.

As explained above, according to the present invention, when a character pattern becomes unrecognizable in the mask matching method and a retry is performed, the reference point of a character pattern is corrected to a position that is inferred from the reference point of a nearby character pattern that was recognizable. By doing so, it is possible to salvage a large number of characters that were conventionally rejected as unrecognizable by making them recognizable, thereby significantly improving the reading rate and shortening the reading time.

Note that the reference point of the pattern is not limited to the center of the pattern.

[Brief explanation of drawings]

1A to 1E are schematic explanatory diagrams of a conventional example, FIG. 2 is an explanatory diagram of the principle of the present invention, and FIG. 3 is an explanatory diagram showing the configuration of an embodiment of the present invention. ,
12 is an A/D conversion section, 13 is a data storage section, 14
15 is a character pattern center detection circuit, 15 is a comparison circuit,
16 is a standard pattern table, 17 is an interface, and 21 is a character center correction section.

Claims (1)

[Claims] 1 Character reference points are determined from the shape of a character pattern read by an optical character reading means, and unrecognized characters are A character recognition method characterized in that when a character pattern occurs and a retry is performed, the reference point of the character pattern is corrected to a position analogous to the reference point of a character pattern that has already been recognized, and a retry is performed using a mask matching method.