JPH09185683A - Method and device for processing image for character checking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prepare standard character data even when the row or column of characters of a device to be tested (DUT) to be defined as a reference is inclined. SOLUTION: The description plane of DUT, where the characters to be defined as a standard are described, is photographed, provided picture element values (the luminance of picture elements) are stored in an image memory M1, these data are converted into binary data by performing threshold processing and stored in an image memory M2, noises are reduced by thinning these data, these data are stored in an image memory M3, and these data are returned into original thickness by reforming thickening processing and stored in an image memory M4. A circumscribed rectangle is found for each character from these data, its coordinate positions are stored in a circumscribed rectangle memory M6, the image data in the image memory M1 are punched out by these circumscribed rectangle data, and the image data for each character are segmented and stored in an image memory M5 as standard character data. Further, the inclining angle of row line/column line is found and the inclination corrected standard character data can be provided as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing method for obtaining standard character data as a reference in an apparatus for inspecting characters written on a DUT (device under test) package and an improvement in the apparatus.

[0002]

2. Description of the Related Art In a character inspection device for a DUT package,
Take a picture of the inscription on the surface of the DUT package with a camera,
The image data (matrix data of pixel values representing the brightness of the pixel) is stored in the image memory, and the character data is compared with the standard character data stored in the standard character memory one by one to judge whether the image is good or bad.

The image processing apparatus shown in FIG. 4 is used to create standard character data serving as a reference. The method of creating standard character data by the image processing apparatus will be described below. (A) A DUT to be used as a standard model of character data is selected from the DUTs, a character notation surface is photographed by a camera, and the image data (pixel value) is stored in the image memory M1.

(B) When plural lines of written characters are printed substantially parallel to the X-axis as shown in FIG. 5A, the arithmetic unit C1
Then, the sum L1 (y) of pixel values (luminance) on the Y axis (FIG. 5B) is obtained from the data in the image memory M1, and the position on the Y axis of the character of each line is obtained from the change in the luminance characteristic. (C) The calculation unit C2 obtains the sum L2 (x) of pixel values on the X axis for each row (FIG. 5C), and obtains the position of each character on the X axis from the change in the luminance characteristic.

(D) In the character slicing section C3, the X and Y coordinates of each character are used to extract 1 from the data in the image memory M1.
Image data composed of a dot matrix for each character is cut out and stored in the image memory M2 as standard character data serving as a reference.

[0006]

In the conventional image processing apparatus, for example, one side of the surface of the DUT is set on the X axis of the coordinates, and the sum L1 (y) of the pixel values on the Y axis of each row is obtained. Therefore, as shown in FIG.
If the line of characters of UT is tilted, the sum L1 of pixel values
(Y), as shown in FIG. 6, the valley between the rows does not appear,
There is a problem that the Y coordinate position of each line cannot be detected and standard character data cannot be obtained.

An object of the present invention is to ensure that standard character data can be stored even if the row (or column) of the character of the DUT to be referenced is tilted.

[0008]

[Means for Solving the Problems]

(1) The inventions of claims 1, 2 and 3 are as follows (2),
The image processing apparatus adopts the image processing method described in the items (3) and (4), and since there is much overlap with the following description, detailed description thereof will be omitted. (2) In the image processing method of the character inspection apparatus according to claim 4, the pixel value (luminance of pixel) obtained by photographing the notation surface of the DUT on which the characters to be standardized are photographed is stored in the image memory 1.
The image data in the image memory 1 is thresholded to be converted into binary data, stored in the image memory 2, the data in the image memory 2 is thinned, and stored in the image memory 3. , The data in the image memory 3 is thickened,
It is stored in the image memory 4.

The circumscribed quadrangle is obtained for each character from the data in the image memory 4, the coordinate position is stored in the circumscribed quadrangle memory, and the circumscribed quadrangle (data) stored in the circumscribed quadrangle memory is used to store the circumscribed quadrangle in the image memory 1. The image data is punched out, the image data for each character is cut out, and stored in the image memory 5 as standard character data. (3) In the invention of claim 5, in claim 4, the area of the circumscribing quadrangle for each character is calculated and compared with a threshold value, and those less than or equal to the threshold value are excluded from the circumscribing quadrangle corresponding to one character. It is a thing.

(4) According to the invention of claim 6, in claim 4, a straight line parallel to each row line (or column line) of the notation character is obtained from the data of the circumscribed quadrangle memory, and the horizontal line (or vertical line) of the straight line is obtained. ) Is formed, and the image data cut out for each character of the image memory 5 is calculated by inclining the image data by one θ and stored in the image memory 6.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The pixel value (pixel brightness) obtained by photographing the notation surface (FIG. 2A) of the DUT, which is described by the character to be used as a reference (for example, white on a black background) from the DUT, is stored in the image memory M1. To be done. The data in the image memory M1 is input to the threshold processing unit 2,
It is thresholded, converted into binary data of "1" or "0", and stored in the image memory M2.

If there is dust or scratches on the written surface of the DUT,
When the data in the image memory M2 is displayed, noise N appears on the screen as shown in FIG. 2B. In order to erase the noise N, the data in the image memory M2 is input to the thinning processing unit (also referred to as contraction processing unit) 3, and the processing for thinning the character lines is performed (FIG. 2C), and the noise-erased processing is performed. The subsequent data is stored in the image memory M3. The data in the image memory M3 is input to the thickening processing unit (also called expansion processing unit) 4,
The thickness of the characters is returned to the thickness before the thinning process (Fig. 2
D), and stored in the image memory M4. The techniques of the thinning processing and the thickening processing described above are well known in the field of image processing.

The data in the image memory M4 is input to the labeling processing unit 5, the circumscribed quadrangle Sq of each character is calculated (FIG. 2E), and the X and Y coordinates thereof are stored in the circumscribed quadrangle memory 6. Each side of the circumscribing quadrangle Sq is parallel to the X-axis or the Y-axis that serves as a reference for the pixel position coordinates. If there is noise that cannot be eliminated by the above-described thinning processing and thickening processing, the labeling processing unit 5 calculates the area of each circumscribing quadrangle Sq, compares it with a threshold value, and It is desirable to exclude objects from the circumscribed rectangle.

In the character slicing section 7, the image data of the image memory M1 is punched out by a circumscribed quadrangle with a margin of 2 to 3 pixels on each of the vertical and horizontal lines of the circumscribed quadrangle corresponding to each character of the circumscribed quadrangle memory 6. Is created, and the image memory M is used as standard character data to be used as a reference.
Stored in 5. A method for obtaining the circumscribed quadrangle Sq and cutting out each character from the image in the image memory M1 is described in FIG.
Even if a plurality of lines are inclined with respect to the X-axis direction as shown in (a), since the circumscribing quadrangle Sq of each character can be obtained, the conventional problem does not occur. The same applies when the column lines are inclined.

In some cases, it is desired to virtually rotate each row (or column) in the opposite direction by the tilt angle θ of each row (or column) to correct the tilt, and use the obtained image data of each character as a reference. There are cases. In that case, the row line / column line inclination angle calculation unit 8 calculates, for example, the coordinates (x1
(I), y2 (i)) is used to calculate the straight line LN corresponding to the row (or column) by the least squares method, and then the straight line LN
The angle θ between N and the X (or Y) axis is calculated. The inclination angle correction unit 9 calculates the image data of the character (FIG. 3B) whose inclination is corrected by tilting (rotating) the image data of each character in the image memory M5 in the opposite direction by the angle θ. Then
It may be stored in the image memory M6.

[0016]

As described above, according to the present invention, the circumscribed quadrangle corresponding to each character is obtained, and the image (data) of each character written in the DUT to be used as the reference stored in the image memory is circumscribed quadrangle. Punched out, cut out as standard character data, and stored in the image memory M5. As a result, as shown in FIG. 3A, even if each row line (or column line) is slightly inclined, the circumscribed quadrangle can be obtained, so that each character data can be reliably cut out.

Further, according to the present invention, standard character data in which the inclination angle of each row line (or column line) is corrected can be obtained if necessary, which is very convenient.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of an image displaying each data in the image memories M1 to M4 of FIG.

3A is a circumscribed quadrangle when a row line La of an image displaying data in the image memory M4 of FIG. 1 is inclined,
The figure which shows the straight line LN calculated | required by the least squares method, and an example of the inclination angle, (b) shows the image when the inclination is corrected by rotating the character data of the image memory M5 by -θ corresponding to (a). The figure which shows each character data of memory M6.

FIG. 4 is a block diagram of an image processing apparatus used in a conventional character inspection apparatus.

FIG. 5 is a diagram for explaining a conventional image processing method.
Is an example of a DUT notation character to be used as a reference, B is a graph showing the sum L1 (y) of pixel values of A on the Y axis, and C
Is a graph showing the sum L2 (x) of pixel values on the X axis of the first row of A.

FIG. 6 is a diagram for explaining another example of the conventional image processing method, where A is a line in which a notation character of a DUT to be a reference is inclined, and B is a line on the Y axis of A. The graph which shows the sum L1 (y) of pixel values.

Claims (6)

[Claims] 1. An image memory 1 for storing a pixel value (luminance of a pixel) obtained by photographing an image surface of a DUT on which characters to be standardized are written, and data of the image memory 1 are stored. Threshold processing means for thresholding and binarizing, image memory 2 for storing the binary data obtained by the threshold processing means, and thinning processing for the data in the image memory 2 ( Shrinking processing) to remove noise to reduce noise, image memory 3 for storing data obtained by the thinning processing means, and thickening processing (expansion processing) for the data in the image memory 3. By using the thickening processing means for restoring the thickness of the character to the original, the image memory 4 for storing the data obtained by the thickening processing means, and the data in the image memory 4 for each character. Labeling process to find the circumscribed rectangle A column, a circumscribing quadrilateral memory that stores the coordinate information of the circumscribing quadrangle for each character obtained by the labeling processing unit, and the circumscribing quadrilateral of the circumscribing quadrangle memory punches out the image data of the image memory 1 to obtain one character. An image of a character inspection device, comprising: character cutout means for obtaining image data for each character; and image memory 5 for storing the image data for each character obtained by the character cutout means as standard character data. Processing equipment. 2. The labeling processing means according to claim 1, wherein the labeling processing means obtains an area of the circumscribing quadrangle and compares it with a threshold value, and excludes a value less than or equal to the threshold value from the circumscribing quadrangle corresponding to one character. Image processing device of character inspection device. 3. The straight line parallel to each row line (or column line) of a written character is obtained from the data of the circumscribed quadrilateral memory according to claim 1, and an angle θ formed between the straight line and a horizontal line (or vertical line) is obtained. Row line (column line)
The tilt angle calculating means and the tilt angle for calculating the image data of each character which is tilted in the opposite direction by the tilt angle θ obtained by the tilt angle calculating means with respect to the image data cut out for each character of the image memory 5. An image processing apparatus of a character inspection apparatus, comprising: a correction unit; and an image memory 6 for storing image data of each character whose inclination angle is corrected. 4. A pixel value (pixel brightness) obtained by photographing a notation surface of a DUT on which characters to be standardized are recorded is stored in the image memory 1, and the data in the image memory 1 is stored. Threshold processing is performed to convert it to binary data, which is stored in the image memory 2. The data in the image memory 2 is thinned and stored in the image memory 3. The data in the image memory 3 is thickened. Then, the circumscribed quadrangle is stored in the image memory 4, the circumscribed quadrangle is obtained for each character from the data in the image memory 4, the coordinate position is stored in the circumscribed quadrangle memory, and each circumscribed quadrangle (data is stored in the circumscribed quadrangle memory (data ), The image data in the image memory 1 is punched out, and 1
An image processing method for a character inspection device, wherein image data for each character is cut out and stored as standard character data in the image memory 5. 5. The area according to claim 4, wherein the area of the circumscribed quadrangle for each character is calculated and compared with a threshold value, and those below the threshold value are excluded from the circumscribed quadrangle corresponding to one character. Image processing method for character inspection device. 6. The straight line according to claim 4, wherein a straight line parallel to each row line (or column line) of the written characters is obtained from the data of the circumscribed quadrangle memory, and the horizontal line (or vertical line) of the straight line is obtained.
The character inspection device is characterized in that the angle θ formed by the image memory 5 is calculated, and the image data cut out for each character of the image memory 5 is calculated by inclining the image data by one θ and stored in the image memory 6. Image processing method.