JPH07192088A - Method and device for processing picture - Google Patents

Abstract

PURPOSE:To accurately correct the skew even for a handwritten character string for which the size of characters and pitches, etc., are not unified. CONSTITUTION:This picture processing method and device for recognizing and correcting the inclination amount of a character string so as to recognize optically read characters is provided with an affine transformation circuit 2 for performing a rotation processing to inputted pictures, a profile circuit 3 for obtaining the projection of the character string during the rotation processing, a labelling processing part 4 for estimating the average length of the character, an inclination amount detection circuit 5 for comparing a projection amount and the estimated length of the character and judging a rotation angle for which a difference is minimum as the inclination amount of the character string and an inclination correction circuit 6 for correcting the inclination of the picture data of the character string.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, and more particularly to an image processing method and an image processing apparatus for performing a correction process so that a character string inclined to recognize a handwritten character can be read.

[0002]

2. Description of the Related Art In recent years, there has been a device for reading and sorting the address of mail items by a character reading device. In such an apparatus, the skew amount, which is the amount of inclination of the written character string, is read, the process of rotating the character string is performed, and the character string is recognized.

Conventionally, this skew amount is read by
The projection of the character string in each direction is obtained, and the character string is rotated so that the projection amount is minimized.

[0004]

However, in the case of a character having a constant character size such as a print type, the skew amount can be obtained by the characteristics such as the projection as described above, but in the case of a handwritten character, Since the character size, pitch, etc. are not constant, it is difficult to obtain the skew amount from the projection as described above.

Further, even if the skew amount is obtained by this method, the accuracy becomes very low, and the correction cannot be made with a large skew amount.

Therefore, the present invention provides an image processing method and an image processing apparatus capable of performing accurate skew correction even for a handwritten character string whose character size, pitch, etc. are not standardized. To aim.

[0007]

In the present invention, the first means for solving the above problems is an image processing method for correcting the inclination of a character string in order to recognize an optically read character. A first step of extracting an amount of projection in a direction substantially perpendicular to the direction in which the character string is to be written while rotating an image of the character string optically read, and labeling the read character string A second step of performing processing to estimate an average length of each character in a direction substantially perpendicular to the character string direction; the projection amount extracted in the first step; and the second step estimation The third step of determining the rotation angle that minimizes the difference between the average length of the character and the inclination amount of the character string, and the inclination of the character string from the rotation angle determined in the third step. Fourth step to correct When an image processing method characterized by comprising the.

The second means of the present invention is an image processing method for correcting the inclination of a character string for the purpose of recognizing an optically read character. A first step of storing in memory,
In the first step, the image data stored in the image memory is subjected to an affine transformation process and rotated while a profile process projects the image in a direction substantially perpendicular to the direction in which the character string should be written And the labeling process for the character string stored in the image memory by the first step, and the average length of each character in the direction substantially perpendicular to the direction in which the character string is to be written. And a rotation angle that minimizes the difference between the projection amount taken in the second step and the average length of the character estimated in the third step. It is characterized by comprising a fourth step of determining the amount of inclination of the column and a fifth step of correcting the inclination of the character string from the rotation angle determined by the fourth step. An image processing method.

Further, the third means of the present invention is to rotate the image of the optically read character string in the image processing apparatus for correcting the inclination of the character string in order to recognize the optically read character. While the image rotation means for extracting the projection in the direction substantially perpendicular to the direction in which this character string should be written,
Labeling processing is performed on the read character string,
A character size estimating means for estimating an average length of each character in a direction substantially perpendicular to the character string direction, the projection amount extracted by the image rotating means, and the character size estimating means. The inclination amount determining means for determining the rotation angle having the minimum difference from the average length of the character as the inclination amount of the character string, and the inclination angle of the character string is corrected from the rotation angle determined by the inclination amount determining means. The image processing device is characterized by comprising:

The fourth means of the present invention stores the image data of the optically read character string in an image processing apparatus for correcting the inclination of the character string in order to recognize the optically read character. And an image memory for performing an affine transformation process on the image data stored in the image memory and rotating the image data to take a projection amount in a direction substantially perpendicular to the direction in which the character string is to be written in the profile process. A character that estimates the average length of each character in a direction substantially perpendicular to the direction in which the character string is written by performing a labeling process on the character string stored in the image memory and rotating means. The rotation angle that minimizes the difference between the size estimation means, the projection amount taken by the image rotation means, and the average length of the characters estimated by the character size estimation means is the inclination of the character string. And determining inclination amount determining means and an image processing apparatus characterized a correction means for correcting, in that it consists of the string inclination from the rotation angle is determined by the tilt amount determining means.

[0011]

According to the present invention, the image of the input character string is projected while rotating, and the average length of the character is estimated by the labeling process, and the projection amount and the estimated average of the character are calculated. The rotation angle that minimizes the difference from the length is determined as the inclination amount of the character string, and the inclination of the character string is corrected.

Further, according to the present invention, the image data of the input character string is stored in the image memory, the image data is subjected to affine transformation processing and rotated while projection is performed by the profile processing to label the character string. Then, the average length of the character is estimated, and the rotation angle that minimizes the difference between the projection amount and the estimated average length of the character is determined as the inclination amount of the character string, and the inclination angle of the character string is determined. To correct.

Further, according to the present invention, the image rotation circuit takes a projection while rotating the image of the input character string, and the character size estimation circuit estimates the average length of the character by the labeling process. . Then, the inclination amount estimation circuit determines the rotation angle that minimizes the difference between the projection amount and the estimated average length of the character as the inclination amount of the character string, and the correction circuit determines the character string based on the inclination. Correct the inclination of.

Further, according to the present invention, the affine transformation circuit rotates the input image, and the profile circuit takes a projection of the character string being rotated by the affine transformation circuit. Then, the labeling circuit estimates the average length of the character, and the inclination amount detection circuit compares the projection amount with the estimated average length of the character to determine the rotation angle with the minimum difference as the character string. And the correction circuit corrects the inclination of the image data of the character string. Therefore, in the present invention, the accurate skew amount is obtained by taking the projection at each rotated angle to obtain its height, and comparing this height with the average length of the characters of the character string estimated in advance. Is something that can be done.

[0015]

Embodiments of an image processing method according to the present invention and an image processing apparatus to which this method is applied will be described below.

FIG. 1 is a block diagram showing the arrangement of an image processing apparatus according to the present invention.

In the figure, 1 is an image memory in which image data read by a known image reading means is stored, 2
Is an affine transformation circuit, and as shown in FIG. 4, the inputted image data is rotated by, for example, 1 ° increments by homomorphic transformation within a preset range and stored in a memory in the affine transformation circuit. A profile circuit 3 projects in the y-axis direction on the image at each angle after the affine transformation. A labeling circuit 4 estimates the average size a of the characters. Reference numeral 5 denotes a skew amount detection circuit which is a tilt amount detection circuit, and compares the projection heights respectively taken with V and the tentatively estimated average height a of the characters obtained by the labeling circuit 4, and finds the smallest difference. Select one. A skew correction circuit 6 performs skew correction of rotating at an angle θ of the skew amount detected by the skew correction circuit, which is an inclination correction circuit, and outputs an image. A MPU (microprocessor) 7 controls all of the above circuits.

FIG. 2 is a flowchart showing the operation of the image processing apparatus according to this embodiment.

When the input image is input to the image memory (S
T1), the accumulated image is simultaneously transferred to the affine transformation circuit 2 and the labeling circuit, and the affine transformation circuit rotates the input image by 1 ° within a set range (ST2). Then, the rotated image data is output to the profile circuit 3, profile processing is performed on each image data, projection is taken, and its height is obtained (ST
3).

On the other hand, the labeling circuit 4 labels each character of the input image and obtains the average height of the characters in the projection direction (ST4). Then, the projection height and the average height of the characters are input to the skew amount detection circuit,
The height V of the profile is compared with the average height a of the characters, and the angle having the smallest difference is selected (ST5).

The skew amount correcting circuit 6 corrects and rotates the image based on the selected skew amount and outputs it. Here, each processing is actually controlled by the MPU (ST7).

FIG. 4 shows a specific example of image rotation.
The input image "Chiyoda-ku, Tokyo" is rotated within a preset range by isomorphic affine transformation, and projection is performed on each. This projection is displayed as a distribution amount beside the character (FIG. 4 (1)).

The projection height V and the tentatively estimated average height a of the character after labeling are referred to, and the rotation angle θ when the difference between V and a is the minimum is set as the skew amount. A correction for rotating the character string is performed based on the skew amount (FIG. 4 (2)).

[0024]

As described above, according to the present invention,
The input image is rotated, the projection at each rotated angle is taken, the height is calculated, and it is compared with the estimated average length of the characters in the character string. In particular, it is possible to obtain an accurate skew correction amount even for handwritten characters in which the size, pitch, etc. of the characters are different, so that accurate skew correction can be performed and the character recognition rate can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an image processing apparatus according to the present invention.

FIG. 2 is a flowchart showing an operation of the image processing apparatus shown in FIG.

FIG. 3 is a flowchart showing an operation of the image processing apparatus shown in FIG.

FIG. 4 is an explanatory diagram showing a state of rotation and projection of image data of the image processing apparatus shown in FIG.

[Explanation of symbols]

 1 image memory 2 affine conversion circuit 3 profile circuit 4 labeling circuit 5 skew amount detection circuit 6 skew correction circuit 7 MPU

Claims (4)

[Claims] 1. In an image processing method for correcting the inclination of a character string to recognize an optically read character, the character string should be described while rotating the image of the optically read character string. A first step of extracting a projection amount in a direction substantially perpendicular to the direction, and a labeling process for the read character string, and an average length of each character in a direction substantially perpendicular to the character string direction. And a rotation angle at which the difference between the projection amount extracted in the first step and the average length of the character estimated in the second step is minimized, And a fourth step of correcting the inclination of the character string from the rotation angle determined in the third step. 2. An image processing method for correcting inclination of a character string for recognizing an optically read character, comprising a first step of storing image data of the optically read character string in an image memory. In the first step, an affine transformation process is performed on the image data stored in the image memory and the image data is rotated while a projection is performed in a direction substantially perpendicular to the direction in which the character string is to be written in the profile process. 2), the labeling process is performed on the character string stored in the image memory by the first step, and the average of each character in the direction substantially perpendicular to the direction in which the character string is to be written is calculated. The third step of estimating the length, and the difference between the projection amount taken in the second step and the average length of the character estimated in the third step is the largest. And a fifth step of correcting the inclination of the character string from the rotation angle determined by the fourth step. Characterized image processing method. 3. An image processing apparatus for correcting the inclination of a character string for recognizing an optically read character, wherein the character string should be described while rotating the image of the optically read character string. An image rotation unit that extracts a projection in a direction substantially perpendicular to the direction, and performs labeling processing on the read character string,
A character size estimating means for estimating an average length of each character in a direction substantially perpendicular to the character string direction, the projection amount extracted by the image rotating means, and the character size estimating means. The inclination amount determining means for determining the rotation angle having the smallest difference from the average length of the character as the inclination amount of the character string, and the inclination of the character string is corrected from the rotation angle determined by the inclination amount determining means. An image processing device, comprising: 4. An image processing apparatus for correcting the inclination of a character string for the purpose of recognizing an optically read character, comprising: an image memory for storing image data of the optically read character string; Image rotation means for taking an amount of projection in a direction substantially perpendicular to the direction in which the character string should be written in profile processing while rotating by performing affine transformation processing on the stored image data, and storing in the image memory Character size estimating means for estimating the average length of each character in a direction substantially perpendicular to the direction in which the character string is to be written, and the image rotation. Inclination amount determining means for determining the rotation angle that minimizes the difference between the projection amount taken by the means and the average length of the characters estimated by the character size estimating means as the inclination amount of the character string. An image processing apparatus for a correcting means for correcting the character column slope from the rotation angle is determined by the tilt amount determining means, in that it consists characterized.