JPH03111982A - Character segmenting method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for cutting out characters from a character image written in an arbitrary frame in a character recognition device (OCR).

[Prior art] Conventional methods for cutting out characters from within a frame include a method in which the position of the frame on a specified form is given in advance, and a method to detect the inclination or positional shift of the form when inputting a single image. A method of setting a mark, correcting the position of the frame on the form according to the position of this mark, and cutting out the characters, or Japanese Patent Application Laid-Open No. 60-4
As seen in Japanese Patent No. 5884, a method is known in which a character frame is extracted by projecting an image in which characters are written in a frame in two orthogonal directions, and then the character frame is removed.

[Problem to be solved by the invention]

In the prior art, the method of assigning the frame position in advance has the disadvantage that the frame is limited to a specific frame, and when a different frame is used, a new frame position must be assigned, resulting in a lack of versatility. In addition, the method of placing marks on forms is based on the noise generated by scanners, etc. when inputting images and the blurring of images.

This has the disadvantage that the marks and frames used to detect inclination and positional deviations may become blurred, and accurate correction cannot be performed, making it difficult to cut out characters. Furthermore, the conventional method of removing character frames by projection has the disadvantage that if there are characters touching the frame line or the form is tilted, one character will be cut off when removing the character frame by projection. Ta.

The purpose of the present invention is to
The goal is to accurately and reliably cut out characters.

[Means to solve the problem]

In order to achieve the above object, claim (1) relates to an input image of a form in which characters are written in a frame.

Obtain frame coordinates by frame line recognition, cut out a circumscribed rectangle including the top, bottom, left, and right frame lines for each frame obtained from the frame coordinates, and then cut out characters based on vertical and horizontal projections. It is characterized by

Further, in claim (2), the present invention is characterized in that the range in which the frame line exists in the circumscribed rectangle including the upper, lower, left, and right frame lines is determined, and the frame line is removed from the circumscribed rectangle within this range.

Furthermore, in claim (3), a horizontal or vertical projection is obtained for an image including margins on the top, bottom, left, and right sides obtained after removing the frame line from the circumscribed rectangle, and the projection is performed from the edge toward the center. , is characterized by determining the position from which characters are cut out.

[For production]

In claim (1), in order to extract characters based on the frame coordinates obtained by frame line recognition, each frame is cut out using a circumscribed rectangle that includes the upper, lower, left, and right frame lines. rear,
By cutting out characters based on vertical and horizontal projections, accurate cutting is possible.

In claim (2), by determining the upper, lower, left, and right frame line search ranges and removing the frame lines within this range, it is possible to cut out characters when cutting out characters that touch the frame lines by projection. can be kept to a minimum.

In claim (3), when cutting out a character from an image that includes margins on the top, bottom, left, and right sides obtained after removing the frame line, the target character can be extracted by determining that pixels smaller than a certain distance are noise. It can be cut out reliably.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram of a processing device that implements the character segmentation method of the present invention. The image input device 11 is composed of a scanner or the like, and reads forms with characters written in frames.

Digital image information read by the image input device 11 is stored in an input image memory 13. The CPU (central processing unit) 12 is.

Frame line recognition is performed on the image information in the input image memory 13, character images including the frame lines are cut out and stored in the working memory 14.
, remove frames and margins, and cut out the characters.

FIG. 2 shows a flowchart of character extraction processing performed by the CPU 12, and an embodiment of the character extraction method of the present invention will be described in detail below along this flowchart.

Frame line recognition is performed on the input image information of forms stored in the input image memory 13 as preprocessing for character extraction to determine the coordinates of each frame (step 10f). Various methods have been proposed for recognizing frame lines, and any of these methods may be used. From the frame coordinates obtained by this frame line recognition,
One circumscribed rectangle including the upper, lower, left, and right frame lines is cut out and stored in the working memory 14, and characters are cut out in the following order.

First, a frame line search range is determined for the cut out circumscribed rectangle (step 102). FIG. 3 shows the relationship between the circumscribed rectangle obtained by frame line recognition and the frame line search range. The frame line search range is the range where the frame line exists, and is used to determine the next frame line removal position.As shown in Figure 3, the frame line search range is the range where the frame line exists. Become.

These ranges are determined by geometric formulas depending on the position of each frame relative to the frame body.

Next, upper and lower frame line removal positions are determined from the cut out circumscribed rectangle according to predetermined frame line removal position determination conditions, and the upper and lower frame lines are removed (step 103). Thereafter, the left and right side frame line removal positions are determined based on the same frame line removal position determination conditions, and the left and right frame lines are removed (step 104).

In determining this frame line removal position, the maximum projection value is determined within the frame line search range obtained in step 102.

A search is started from that position toward the center of the frame line within the same range to determine the frame line removal position. In this case, it is necessary to satisfy the following two conditions.

(1) The current projection value is less than a certain value based on the maximum projection value. (2) The next projection value is greater than or equal to the current projection value. When the current position satisfies this condition, the current position is set as the frame line removal position. .

If the above two conditions are not satisfied, the innermost position of the frame line search range is set as the frame line removal position.

The conditions for determining the frame line removal position are illustrated in FIG. 4. Here, (a) is (]).

That is, if the current projection is a constant value based on the maximum projection value, (b) is the case of (2), that is, the next projection ≧ the current projection, and if these are satisfied, the current projection Set the projection as the frame line removal position. (Q) is a case where neither conditions (1) nor (2) are satisfied, and in this case, the innermost position of the frame line search range is set as the frame line removal position.

Regarding the example of FIG. 3, the image after removing the upper and lower frame lines is shown in FIG. 5, and the image after removing the left and right frame lines is shown in FIG. 6.

Next, for the image that includes margins on the top, bottom, left, and right, which was obtained by removing the top, bottom, left, and right frame lines, the left and right margins are removed according to the predetermined conditions for determining the character extraction position, and the characters are removed in the X direction (horizontal). (step 105). Thereafter, the upper and lower margins are removed and the start and end positions in the Y direction (vertical direction) are determined according to the same character cutout position determination conditions (step 106), and the cutout of one character is completed.

When determining the position to cut out characters from the edges of the image toward the center from an image that includes margins on the top, bottom, left, and right, the following (1) is the necessary condition, and (2) (3)
).

(1) The area of continuous projections after the current position is greater than or equal to the minimum projected area (2) After the current position, projections with a minimum projection length or longer exist continuously for a minimum projection length or more (3) Projections at a certain specific position after the current position When the current position satisfies these conditions, the current position is set as the character cutting position. FIG. 7 illustrates the conditions for determining the character cutting position described above, where (a) is (1), (b) is
) corresponds to case (2), and (c) corresponds to case (3).

If the left and right margins are removed from the image after removing the frame lines in Figure 6, it will look like Figure 8, and if the top and bottom margins are removed, it will look like Figure 9, where one character can be cut out. finish.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a circumscribing rectangle including the upper, lower, left, and right frame lines is calculated for each frame based on the frame coordinates obtained by frame line recognition for an arbitrary frame. After cutting out characters, characters are cut out based on vertical and horizontal projections, thereby making it possible to perform more accurate character cutting with excellent versatility.

Furthermore, by determining the top, bottom, left, and right frame line search ranges for the cut out circumscribed rectangle and removing the frame lines within this range, it is possible to minimize the cutting off of characters. By removing the upper, lower, left, and right margins obtained after removing lines, it is possible to reliably cut out the desired character from which noise has been removed.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a processing device that implements the character segmentation method of the present invention, FIG. 2 is a flowchart of an embodiment of the character segmentation method of the present invention, and FIG. 3 is the relationship between the circumscribed rectangle and the frame line search range. Figure 4 is a diagram showing the conditions for determining the frame line removal position, Figures 5 and 6 are diagrams showing the image after frame line removal, and Figure 7 is a diagram showing the conditions for determining the character cutting position. ,
FIGS. 8 and 9 are diagrams showing images after margin removal. 11... Image input device, 12... CPU. 13... Input image memory, 14... Working memory. Ward 8, Figure 9

Claims (3)

[Claims] (1) In a method of cutting out characters from an image in which characters are written in an arbitrary frame, the frame coordinates are obtained by frame line recognition, and the upper, lower, left, and right frame lines are included for each frame obtained from the frame coordinates. A character cutting method characterized in that after cutting out a circumscribed rectangle, characters are cut out based on vertical and horizontal projections. (2) The character cutting method according to claim (1), characterized in that the range in which the frame line exists in the circumscribed rectangle including the upper, lower, left, and right frame lines is determined, and the frame line is removed from the circumscribed rectangle within this range. . (3) Find the horizontal or vertical projection of the image obtained after removing the frame line from the circumscribed rectangle, which includes margins on the top, bottom, left, and right sides, and position to cut out characters from the edge toward the center. 3. The character cutting method according to claim 2, further comprising determining the character segmentation method.