JPS6360322B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a seal stamp verification method, and more particularly to an inclination angle detection method for accurately detecting the inclination angle of a seal imprint pattern on a seal stamp.

(Background Art) In general, a seal verification machine uses a position detection section and an inclination angle detection section to detect the center coordinates and inclination angle of a stamp pattern to be verified, which is obtained by reading an uninspected seal imprint by a reading section, and detects the registered seal imprint by using a position detection section and an inclination angle detection section. The center coordinates and inclination angle of the are detected by the position detecting section and the inclination angle detecting section, respectively, and the positions of the stamp imprint patterns to be matched are aligned according to the detection results so that the center point and the inclination angle of both stamp patterns coincide with each other. After aligning the positions in the seal imprint comparing section, the two seal imprint patterns are compared, and based on the results, the match determining section determines whether the two imprint patterns match or do not match, and also detects minute errors in position detection. In order to compensate for minute errors in tilt angle detection, the output of the match determination section is fed back to the position matching section, and after repeating the operation of finely adjusting the position and tilt angle several times, the authenticity of the stamp to be verified is determined. This is a device that makes judgments.

Therefore, in order to reduce the number of repetitions of "fine adjustment of position alignment" and "imprint comparison", it is required that errors in tilt angle detection and position detection be extremely small.

By the way, in the case of tilt angle detection, it would be better if we could focus on the fact that a seal always has an outer frame and detect the tilt angle from the outer shape characteristics of the outer frame, but the shape of the seal is generally oval, There are three types: round and square. For the oval and square shapes, the angle of inclination can be detected from the external features, but in the case of the round shape, it is impossible to detect the angle of inclination from the external features. be. Therefore, the internal features inside the outer frame will be used, and we will finally perform two-dimensional exploration over the entire area of the so-called inner pattern, which is the entire seal imprint pattern with only the outer frame pattern removed, and recognize the characters. The process would be complicated. Therefore, as a conventional example for solving this problem, there is Japanese Patent Application No. 1983-205114, which has already been filed by the present applicant.
This conventional example discloses an inclination angle detection method that focuses on the characteristic that stamp patterns generally have gaps between characters or between character strings. This is a method that detects gaps between characters or between character strings (hereinafter abbreviated as line of sight), and uses the inclination angle of the line of sight as the inclination angle of the stamp pattern. Although the extracted features are simple even though they refer to the internal features, the processing is relatively simple, and
This method is suitable for detecting the inclination angle of a stamp pattern because it can be applied to most stamp patterns.

However, as is clear from the flowchart in Figure 1, in the conventional example, the reference point (hereinafter referred to as the line-of-sight reference point) for searching the line of sight is limited to only the center point of the seal imprint pattern. Figure 2A,
Although it is suitable for general stamp patterns where the line of sight l passes through the center point as shown in Figure 2B, it is also suitable for stamp patterns where the line of sight does not pass through the center point as shown in Figures 2C and 2D. Since the line of sight is searched using the center point of the seal imprint pattern as the line of sight reference point, it is possible to detect the line of sight and the apparent line, but
Since the complete line of sight was not detected, the accuracy of detecting the inclination angle was reduced.

(Problems to be solved by the invention) The purpose of the present invention is to solve these drawbacks.
An object of the present invention is to provide an inclination angle detection method that can reliably detect a line of sight.

(Summary of the Invention) In order to eliminate the above-mentioned drawbacks, the present invention provides an inclination angle detection method for detecting the inclination angle of a given seal imprint pattern. A center point detection process that detects the center point using a formula, a center point detection process that detects the center point from the seal imprint pattern using a predetermined formula for calculating the center of gravity, and a center point detection process that detects the center point from the center point detected by the center of gravity detection process. The centroid point is sequentially stepped in a direction toward the center point detected by the process by a predetermined increment up to a predetermined distance determined corresponding to the distance between the center point and the center point. and a line-of-sight reference point setting process for setting line-of-sight reference points at each of the stepped positions, and a line-of-sight control point setting process that sets a line-of-sight reference point at each of the stepped positions; A line-of-sight detection process that detects a ray that minimizes the number of points as a line-of-sight candidate, and a line-of-sight candidate detected by the line-of-sight detection process is set as a line of sight of the seal imprint pattern, and an inclination angle of the line of sight is determined as an inclination of the seal imprint pattern. and an inclination angle determination process that determines the angle, and determines the moving direction of the line-of-sight reference point without limiting the line-of-sight reference point to the center point, and moves the line-of-sight reference point in this moving direction. detect line of sight,
The angle of inclination is defined as the angle of inclination of the stamp pattern.

(Embodiment) FIG. 3 is a block diagram showing an overview of a series of processes in a first embodiment of the invention. The seal imprint pattern 1 is an object whose inclination angle is to be determined, and the processing described below is executed by processing blocks shown as a center point detection section 2 and a center point detection section 3, respectively.

The center point detection section 2 is a processing block that detects the center point coordinates C (a, b) of the seal impression pattern 1 using an arithmetic expression described below.

The center of gravity detection unit 3 is a processing block that detects the coordinates G(v, w) of the center of gravity of the seal impression pattern 1 using an arithmetic expression described below. Center point coordinates C (a, b) detected by the center point detection section 2 and barycenter point coordinates G (v, w) detected by the center point detection section 3
Both are further processed by the line-of-sight reference point setting unit 4.

The line-of-sight reference point setting unit 4 uses the center point coordinates C (a, b) and barycenter point coordinates G detected in this way.
(v, w) reaches a predetermined distance set corresponding to seal impression pattern 1, for example, the position (X _n , _Yo ) of the dotted line shown in FIG. v, w) in the direction toward the center point coordinates C(a, b) by a predetermined increment, for example, as shown in FIG. Let, the coordinates of the center of gravity G
This is a processing block for setting the line-of-sight reference point of the stamp pattern 1 at (v, w) and the stepped position, respectively.

The line-of-sight detecting unit 5 draws a plurality of rays passing through the line-of-sight reference point obtained by the line-of-sight reference point setting unit 4 at each angle Δθ, and detects the point where each ray overlaps the stamp pattern 1. Detect the number of points, that is, the number N of duplicate sunspots, and calculate the center point coordinates C
(a, b) and the center of gravity point coordinates G (v, w) reaches a predetermined distance set corresponding to the seal impression pattern 1. In order to repeat the process, the process is returned to the line-of-sight reference point setting unit 4, and the radiation of the number N of duplicate sunspots having the minimum value among the numbers N of duplicate sunspots detected in this way is set as the line-of-sight reference point at the line-of-sight reference point. This is a detection processing block that determines line candidates.

The inclination angle determination unit 6 determines the inclination angle θ of the line-of-sight candidate with respect to the X-axis determined by the line-of-sight detection unit 5.
This is a processing block that determines that (not shown) is the inclination angle θ of the stamp pattern 1.

Next, details of a series of processes for detecting the inclination angle from the seal impression pattern 1 will be explained.

As shown in FIG. 5, the center point detection unit 2 is configured to fill the inside of the outer frame of the seal imprint pattern 1 black in the X-axis and Y-axis directions, and then detect the center of gravity of the blacked-out seal imprint pattern 1. do.

FIG. 4 is a pattern diagram for explaining processing using a fill pattern. To explain with reference to FIG. 4, each point of interest P (X _i , Y _j ) [here i
=1 to m, j=1 to n] are classified into at least three types depending on the surrounding seal imprint pattern situation. Part 3
Type refers to (1) a point of interest that satisfies [condition 1] and also satisfies [condition 2], such as points Q and R in Figure 4, (2) either [condition 1] or [condition 2]. There are three types of points of interest, such as point T in Fig. 4, which satisfies (3), and points that do not satisfy (3) [condition 1] and neither satisfy [condition 2], for example, point U in Fig. 4. be.

[Condition 1] means ``The Y coordinate is Y <sub>j</sub> equal to the point of interest, there is a black point of the seal imprint pattern whose X coordinate has a value less than or equal to X <sub>i</sub> , and the Y coordinate is Y <sub>j</sub> equal to the point of interest. ,X
There is a black point in the seal imprint pattern whose coordinates are greater than or equal to X <sub>i</sub> .'' [Condition 2] means, ``The X coordinate is X _i , which is equal to the point of interest, and the Y coordinate is X i.
There is a black point of the seal pattern with a value less than or equal to Y _j , and there is a black point of the seal pattern whose X coordinate is X _i equal to the point of interest, and whose Y coordinate is greater than or equal to Y _j . Value of point corresponding to type (1) |P(X _i ,
Y _j ) | is 2, the value of the point corresponding to type (2) | P
(X _i , Y _j ) | is 1, and the value of the point corresponding to type (3) | P (X _i , Y _j ) | is 0, and the center of gravity is calculated. , b).
The formula for calculating the center point is It is.

The center of gravity detection unit 3 detects that the point of interest P (X _i , Y _j ) is a black point (logical “1”) for each point of interest P (X _i , Y _j ) in the area where the seal imprint pattern is allowed to exist. point), the value of the point of interest |P(X _i , Y _j )| is set to 1, and when the point of interest P (X _i , Y _j ) is a white point (logical "0" point), the value of the point of interest The value of |P(X _i , Y _j )| is 0
year Find the center of gravity G(v, w).

The center point C (a, b) and center of gravity G (v, w) thus obtained have the following properties. That is, since the center point C (a, b) uses a pattern in which the inside of the outer frame is filled, it is generally unrelated to the inner pattern, and the true center point determined from the shape of the seal impression outer frame is detected. On the other hand, the centroid point G (v, w) is determined not only for the outer frame but also for the internal pattern, so if the complexity of the internal pattern, such as the number of strokes of the internal character, is not equal, , the center of gravity is detected at a position that is closer to the complex character than the true center point determined from the outer frame shape of the seal impression.

By the way, in the stamp patterns where the line of sight does not pass through the center point, as shown in Figures 2C and 2D, the line of sight is closer to the simple characters than the center point, and the relative relationship between these is roughly explained. If shown in a schematic diagram, it is as shown in Fig. 5. That is, in FIG. 5, the center point C (a, b) is below the line of sight l, and the center of gravity G (v, w) is the character "mountain".
Because it is biased toward the more complex character "nashi", it is located further below the center point C (a, b). Therefore, after first setting the line-of-sight reference point to G(v, w),
By moving in the direction of C on the line connecting G and C, the desired line-of-sight reference point S can be reached.

The specified distance to move the line-of-sight reference point is
According to the results of an experiment conducted with a mesh resolution of 8 dots/mm, if the distance between two points G and C is converted into the number of meshes and d is the number of meshes, whichever is larger is 2d meshes or (d+5) meshes. Although it has been confirmed that it is sufficient to take the value of , it can be determined experimentally depending on various conditions.

As explained above, in the first embodiment, the line of sight is detected while moving the line of sight reference point from the center of gravity to the center point, so in the case of a general seal impression where the line of sight passes through the center point, Of course, even in the case of a seal imprint where the line of sight does not pass through the center point, the line of sight can be quickly detected, so the inclination angle of the seal imprint pattern can be detected accurately.

In the first embodiment, a method was described in which the center point detection unit uses the center point of a filled pattern that fills in the inside of the outer frame of the seal impression pattern as the center point.
As shown in the figure, the center point C (a, b) of a square or rectangle circumscribing the seal imprint outer frame [where a = (X _S +
X _E )/2, b=(Y _S +Y _E )/2], a similar effect is generally produced using a known method for detecting the difference. As an exception, in the case of a defective seal imprint pattern in which there is significant fading in the outer frame of the imprint, the accuracy of detecting the inclination angle may decrease.

In the first embodiment, a method has been described in which the line-of-sight reference point is always moved in any case. In other words, the specified distance of movement is 2d mesh or (d +
5) If the larger of the two is used,
It will move at least 5 meshes (when G and C are at the same point, that is, d=0). but,
For example, if the center point C and the center of gravity point G match or the distance between them is extremely short (for example, one mesh length or less), there is no need to move them. Therefore, if the distance between the two is smaller than a predetermined threshold value, there is no problem in making a distinction such as not moving the object.

(Effects of the Invention) The present invention does not limit the line-of-sight reference point to the center point, but starts moving the line-of-sight reference point from the center of gravity and moves it in the direction of the center point to ensure the line of sight. Because it detects the line of sight, it is possible to detect the line of sight quickly and reliably, unlike cases where the line of sight reference point is fixed in any case or where the line of sight reference point is moved blindly. It can be used for angle detection. This is particularly effective for round seal impression patterns.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing a series of processing by a conventional inclination angle detection device, FIGS. 2A to D are diagrams showing a seal imprint pattern and its line of sight, and FIG. Fig. 4 is a pattern diagram to explain processing using a fill pattern, and Fig. 5 shows the relative relationships among the center point, center of gravity, and line-of-sight reference point.
A pattern diagram shown on the XY coordinates, FIG. 6 is a pattern diagram for explaining processing according to another embodiment of the present invention. 1... Seal impression pattern, 2... Center point detection section, 3
... Center of gravity detection section, 4... Line-of-sight reference point setting section,
5... Line-of-sight detection section, 6... Inclination angle determination section.

Claims (1)

[Scope of Claims] 1. An inclination angle detection method for detecting an inclination angle of a given seal imprint pattern, comprising: a center point detection process of detecting the center point of the imprint pattern using a predetermined center point calculation formula; a centroid point detection process of detecting the centroid point from the seal imprint pattern using a predetermined formula for calculating the centroid point; and a direction from the centroid point detected by the centroid detection process toward the center point detected by the center detection process. Step by step in a predetermined increment up to a predetermined distance determined corresponding to the distance between the center of gravity and the center point, and set a line-of-sight reference point at the center of gravity and each stepped position. a line-of-sight reference point setting process for setting a line-of-sight reference point, and detecting a line of sight that minimizes the number of points that overlap with the stamp pattern from a group of rays passing through each of the line-of-sight reference points set by the line-of-sight reference point setting process as a line-of-sight candidate. A method for detecting an inclination angle, comprising: line-of-sight detection processing; and inclination angle determination processing for determining the inclination angle of the line-of-sight candidate detected by the line-of-sight detection processing as the inclination angle of the seal imprint pattern.