JP2909132B2 - Optical character reader - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial application field) The present invention relates to an optical character reading device for reading characters written on a form or the like.

(Prior Art) In general, in an optical character reader that reads characters written on a form, characters recorded in a frame (character entry frame) indicating a character entry position provided on the form are read. I have. In particular, when the frame indicating the character entry position provided on the form is printed with a black frame (non-dropout color), the characters to be entered in the character entry frame touch the frame or protrude. The absence of text is a condition for writing characters.

By the way, the recording of characters on a form in which characters (numerals) are recorded by ordinary people, such as a payment notice slip, is often performed manually using a numbering or rubber stamp.

However, the character pitch of the numbering or rubber stamp and the frame pitch of the character entry frame often do not match, and because of manual work, characters are recorded while touching or protruding from the character entry frame. There is.

When reading such a form on which characters are not accurately recorded, the optical character reading apparatus directly executes the character recognition processing. That is, character recognition is performed by deleting a frame portion unnecessary for the character recognition process and cutting out a character pattern for each character from the remaining image. Therefore, when a character touches or protrudes from the character entry frame, the character stroke overlapping the frame portion is also deleted. For this reason, the character pattern used for character recognition is incomplete, and as a result, accurate reading cannot be performed.

(Problems to be Solved by the Invention) As described above, in the conventional optical character reading device,
Even when a character touches or protrudes from the character entry frame, there is a problem that accurate reading cannot be performed because a character recognition process taking this into account is not performed.

The present invention has been made in view of the above points, and makes it possible to reliably contact a character entry frame printed with a non-dropout color such as black or to read a character that is protruded and recorded. It is an object of the present invention to provide a simple optical character reading device.

[Constitution of the Invention] (Means for Solving the Problems) The present invention detects characters recorded in a character entry frame provided on a sheet to be processed by detecting a sheet image of the sheet, and An optical character reading device that reads out a character pattern by cutting out a character pattern from the character image and performing character recognition processing, wherein the frame image detecting means detects a frame image position of a character entry frame from a sheet image, and the character image is detected by the frame image detecting means. At the frame image position, a removed image detecting means for detecting a portion where each dot adjacent to both sides of the frame image position is a white dot as a portion to be removed which does not overlap with the character pattern,
Image removing means for removing, from the sheet image, a portion to be removed detected by the removed image detecting means, wherein the character pattern is detected from the sheet image obtained as a result of the removal by the image removing means. Things.

(Operation) According to such a configuration, the character entry frame is contacted,
By recording the characters that protrude, even if there is a portion where the character pattern and the frame image overlap, only the non-overlapping portion of the frame image is removed. Accordingly, a character pattern is cut out from the sheet image from which the unnecessary frame image has been removed, and is subjected to character recognition processing with the same quality as the character pattern of the recorded character without contact.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a main part in an optical character reading apparatus according to the embodiment. In FIG. 1, a line buffer 10 stores a sheet image for one line. That is, optical scanning is performed on a form to be processed, and a sheet image including images of characters, character entry frames (black frames), and the like is detected. In the line buffer 10, an image of a line in which characters are recorded (a line provided with a character entry frame) is cut out from the sheet image and stored. The line buffer 10 is connected to a black frame removal circuit 20 for removing a character entry frame so as to leave a character pattern in a sheet image stored in the buffer. The black frame removing circuit 20 is connected to a character extracting circuit 30 for extracting a character pattern for each character from the image from which the solid portion has been removed. The character extracting circuit 30 is connected to a matching circuit 40 that performs a character recognition process on the extracted character pattern. The matching circuit 40 is a dictionary storage memory connected to the circuit.
The standard pattern is read from 50 and matched with the character pattern. The dictionary storage memory 50 stores standard patterns classified for each recognition target character. The result of the matching by the matching circuit 40 is output as a result of the character recognition processing.

 Next, the operation of the embodiment will be described.

FIG. 2 shows an example of a sheet image detected from a form to be processed (a part of a line provided with a character entry frame). When a sheet image as shown in FIG. 2 is stored in the line buffer 10, the black frame removing circuit 20
Detects vertical and horizontal projection histograms of an image. The vertical and vertical lines detected by the black frame removal circuit 20
FIG. 3 shows an example of the horizontal projection histogram. When the projection histogram is detected, an image excluding the horizontal frame is cut out based on the histogram value of the horizontal projection. First, based on the histogram value (the number of black bits) of the horizontal projection, the frame is determined based on whether or not a predetermined value (TH1) has been exceeded. In FIG. 3, the (h, i, j) portion is determined to be a horizontal frame. Then, an image excluding the horizontal frame is obtained by cutting out an image between i and j in which characters are recorded. this is,
This is because if the format of the form to be processed (the position where the character is recorded) is known in advance, it is possible to determine from which position the image is to be cut out based on the frame position. Usually, in an optical character reading device, various information including a format of a form used for a character recognition process is stored in advance.

Next, the black frame removal circuit 20 detects a vertical frame position based on the vertical projection histogram value. This is determined in the same manner as described above, based on whether or not the histogram value of the vertical projection has exceeded a predetermined value (TH2). In FIG. 3, the portions (a to g) are determined to be vertical frames.
When the vertical frame is detected in this way, the black frame removing circuit 20 removes the image of the vertical frame so as not to affect the character pattern of the character that touches or overlaps the character entry frame.

Here, when the frame image portion is removed, whether or not the frame image portion should be removed is determined based on the following conditions. That is, as shown in FIG. 4, the dot indicating the frame is CE, the dot on the left line of CE is LS, and the dot on the right line of CE is RS
Then, if both the dots LS and RS on both sides of the CE are “0” (white dots), it is determined that the dot CE should be deleted (set to “0”). That is, as shown in FIG. 4A, when there is a relationship of (LS = “0”) AND (RS = “0”), CE is set to “0”. Further, when there is a relationship of (LS （“0”) OR (RS ≠ “0”) as shown in FIGS.
= “1” (no change)

Based on such conditions, for each dot of each line (a to g) determined to be a vertical frame, (LS = “0”) AND (R
It is sequentially determined whether or not there is a relationship of S = "0"). As a result, dots for which the above relationship is established are removed, and other dots are left as they are ("1").

For example, when a frame image removing process is performed on a frame intersecting (overlapping) with a character stroke as shown in FIG. 5, a pattern as shown in FIG. become that way. That is, the dots indicated by oblique lines in FIG. 7 that do not overlap with the character strokes are removed, and the dots forming the character pattern are left.

In this manner, unnecessary dots are removed from the lines (a to g) determined to be vertical frames, and as a result, an image of only a character pattern as shown in FIG. 8 is obtained. The character segmentation circuit 30 projects the image shown in FIG.
Character block (1s1e, 2s2e,…, 6s6e) by its projection value
Is detected, and cutout is performed for each character block, that is, for each character pattern. The character extracting circuit 30 transfers the character pattern thus extracted to the matching circuit 40.

The matching circuit 40 performs a character recognition process by matching the character pattern from the character cutout circuit 30 with a standard pattern stored in the dictionary storage memory 50. The result of character recognition in the matching circuit 40 is output as a result of reading characters written on a form.

In this way, even when the image of the character entry frame and the character pattern are mixed and overlapped, only the image of the frame portion can be removed. For this reason, the character pattern used for the character recognition processing has the same quality as the character pattern of the character recorded without touching or protruding from the character entry frame, so that an accurate character recognition processing result can be obtained. it can.

In the above embodiment, only the vertical frame portion of the character entry frame is removed in consideration of the overlap with the character stroke. However, the horizontal frame is also removed by the same processing procedure. May be. in this case,
It is determined whether or not the line should be removed based on one dot above and below the line determined to be a horizontal frame.

Further, in the above embodiment, the thickness of the frame image is represented by a line of one dot. However, even in the case of several dots, the dot to be deleted can be determined by the same method as described above. .

[Effects of the Invention] As described above, according to the present invention, characters are recorded in a form provided with a character entry frame printed with a non-dropout color (black frame) by contacting or overlapping with the frame. Even in this case, since the image of only the frame portion is removed and the character pattern is cut out, an accurate character reading result can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part in an optical character reading device according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of a sheet image detected from a form, and FIG.
The figure shows an example of vertical and horizontal projection histograms.
FIG. 5 is a diagram for explaining the removal of the frame image portion, FIG. 5 is a diagram showing an example of an image to be processed for the frame image removal, FIG. 6 is a partially enlarged view of FIG. 5, and FIG. FIG. 6 is a diagram showing an example of removing the frame image from FIG. 6, and FIG. 8 is a diagram showing an example of an image obtained as a result of removing the frame image. 10 line buffer, 20 black frame removal circuit, 30 character extraction circuit, 40 matching circuit, 50 dictionary storage memory

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-189696 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G06K 9/20 G06K 9/34

Claims (1)

(57) [Claims] 1. A character recorded in a character entry frame provided on a sheet to be processed is detected by detecting a sheet image of the sheet, extracting a character pattern from the sheet image, and performing a character recognition process. In an optical character reading device for reading, a frame image detecting means for detecting a frame image position of the character entry frame from the sheet image; and a frame image position detected by the frame image detecting means, adjacent to both sides of the frame image position. Removing image detecting means for detecting a portion in which each dot to be formed is a white dot as a portion to be removed which does not overlap with the character pattern; and removing the portion to be detected detected by the removing image detecting means from the sheet image. And an image removing means for removing. From results obtained sheet image, an optical character reader, characterized in that the detection of the character pattern.