JPS5810964A - Two-dimensional pattern correcting system - Google Patents

Abstract

PURPOSE:To perform correction and restoration with high quality, by performing pattern correction taking into consideration of relation of connection between unit meshes and between picture elements appeared at a two-dimensional pattern for a line drawing. CONSTITUTION:An arbitrary unit mesh (hatched part) on a symbol representing picture of a two-dimensional pattern is connected to 8 surrounding unit meshes, and four sets of connection relation among 4-unit meshes as (a)-(d) are given to the noted unit mesh, and whether or not the present pattern (regular pattern) of the noted unit mesh is adequate in the relation of the pattern of the surrounding unit meshes, is discriminated. By observing the relation of connection of the four sets, the noted unit mesh or the adjacent unit mesh pattern in which the relation of connection not allowed to the pattern connection condition exists even in one set, are converted into the other regular pattern to correct to obtain permissible regular connections for all the four sets. The recheck and correction for the connection of relation is repeated for the required number of times and the symbol representing picture is converted into a the regular symbol representing picture.

Description

[Detailed Description of the Invention] The present invention is applicable to alphanumeric characters, kanji/kana mixed sentences, graphs and tables,
It relates to the processing of two-dimensional patterns, generally called line figures, such as design drawings, and more specifically, relates to a method for correcting and restoring a distorted and noise-superimposed two-dimensional pattern to its original pattern.

When a two-dimensional pattern called a line figure is transmitted or copied, the quality of the pattern deteriorates. This is due to noise and distortion occurring during transmission or during the copying process. In practice, it is almost impossible to realize a transmission system or a copying mechanism that does not contain any components other than the original pattern. Therefore, there is a need to establish a technique for correcting and restoring a two-dimensional pattern with noise or distortion to its original pattern.

Now, unlike natural images, line figures, which are information sources for texts and drawings, are usually generated using certain means and according to certain rules (i.e., transmission, copying; Deterioration in the quality of a two-dimensional pattern can be thought of as noise, distortion, and deformation into a pattern that does not conform to the above rules. If you correct
It should be possible to restore the original pattern.

The inventor modified and restored the two-dimensional pattern based on this viewpoint, and had already filed a patent application for the dog (Japanese Patent Application No. 56-444).
No. 64). In this method, a specific pattern of unit meshes appearing in a two-dimensional pattern (two-dimensional pattern) is selected in advance as a legal pattern, and out of the patterns of each unit mesh appearing in the two-dimensional pattern to be processed, non-legal patterns are selected. A pattern (illegal pattern) is forcibly converted (=converted) into one legal pattern that has a specific relationship with it.For example, when the size of a unit mesh is mxm pixels, the unit mesh pattern is m
Considering it as a Hamming code of xm bits, an illegal pattern is converted into a legal pattern with the minimum Hamming distance from it.

Furthermore, when there are two L legal patterns with the same Hamming distance, one of the high-quality two-dimensional patterns with a high frequency of appearance is selected and assigned to the illegal 2-turn.

Details of the selection of legal patterns, determination of unit mesh size, conversion of illegal patterns to legal turns, etc. are described in the specification attached to the above patent application, so we will not discuss them further here. Explanation will be omitted.

The present invention is an extension of the previously-filed invention described above, and corrects and restores the two-dimensional (two-dimensional) turn by taking into account the connection relationships between unit meshes and the gluing relationships between pixels. The purpose is to provide a method.

Another object of the present invention is to provide a two-dimensional pattern correction method that takes into account ease of computerization and real-time processing.

However, in the present invention, as in the previously filed invention, (a bilegal pattern is selected, and when an illegal turn appears in the two-dimensional pattern to be corrected, it is converted into one legal pattern. The conversion rule at this time may be the same as that of the previously applied invention, for example, converting an illegal pattern into a legal pattern with a minimum distance between the illegal pattern and the illegal pattern.

The present invention further provides that the legal patterns are adjacent to each other without contradiction as elements of the original two-dimensional pattern.

At the same time, specific pattern connection conditions to be satisfied between these adjacent legal patterns are determined in advance. In other words, legal patterns that are adjacent in a connection relationship that does not satisfy this pattern connection condition are not allowed as elements of the original two-dimensional pattern as they are.

Therefore, a two-dimensional pattern that has completed the conversion process of the above illegal pattern into a legal "turn" or is in the process of converting the illegal pattern (after the illegal pattern has been replaced with a legal pattern by this conversion process) The pattern connection relationship between adjacent unit meshes on a two-dimensional pattern (hereinafter referred to as "symbol notation image") is observed. If the above specific pattern connection condition is not satisfied, the pattern (legal pattern) of one or more unit meshes in the adjacent unit mesh is converted to another legal pattern so as to satisfy the above specific pattern connection condition. The two-dimensional pattern after this processing will be referred to as a "legal symbol notation image" from now on.

The process of obtaining a symbol notation image from a two-dimensional pattern to be processed may be the same as that of the previously filed invention, so further explanation will be omitted, and the conversion from a symbol notation image to a legal symbol notation image will be described in accordance with the drawings. C. Explain in detail.

First, the pattern connection conditions for the distribution will be explained.

Now, assume a square unit mesh with mxm pixel size. This is generally valid. Direct connections between such square unit meshes are vertical (usually
Two types of connections are possible: a connection in the sub-scanning direction of the two-dimensional pattern) and a connection in the horizontal direction (usually in the main-scanning direction of the two-dimensional pattern). However, since the correlation between unit meshes adjacent in the diagonal direction is also quite strong, it is desirable to consider connections in the diagonal direction as well. Therefore, as shown in FIG.
Let us consider the connections between the three unit meshes A, B, C, and D at the same time.

Before determining the pattern connection law, the names of the pixels of the unit mesh are slightly defined. In a unit mesh of mxm size, the pixels at the outermost (two positions) are called peripheral pixels.Among the peripheral pixels, the pixels in the 1st and mth rows (upper and lower end pixels) are connected peripheral pixels regarding vertical connection. , the pixels in the first column and the 1nth column (pixels at the left end and right end) are respectively referred to as connection peripheral pixels regarding the 41G-connection in the horizontal direction.

When the size of the unit mesh is 3 x 3, the surrounding pixels of the unit mesh are shown by hatching in Figure 2 (a), and the connected surrounding pixels of the vertical connection are shown by hatching in Figure 2 (a). The pixels shown by applying soching and the connected surrounding pixels in the horizontal direction correspond to the pixels shown by applying soching in FIG. 2(C).

Next, the following verification value Bk or Wk is defined for the connected peripheral pixels in each direction.

B is a symbol indicating a black pixel, and W is a symbol indicating a white pixel.

Also, k is the same type as each connected peripheral pixel (white or black)
This is the number of pixels connected in the connection direction.

The peripheral values of the peripheral pixels connected in the vertical direction of the unit mesh (legal pattern) of 3×3 size as shown in FIG. 3(a) are as shown in FIG. 3(b).

That is, the pixel in the first row and first column is a white pixel, and including this pixel, three white pixels are arranged in the vertical direction. Therefore, the peripheral value of the connected peripheral pixel is W3. The connected peripheral pixel in the first row and second column is a white pixel, and since two white pixels are lined up in the vertical direction (connection direction), its peripheral value is W2.

Similarly, the connected peripheral pixel in the third row and second column is a black pixel, and since there is only one black pixel lined up in the vertical direction, its peripheral value is B1. Further, the peripheral values of the horizontally connected peripheral pixels are as shown in FIG. 3(C). In other words, the ++++i pixels around the connection in the first row and first column are white pixels,
Horizontal direction (connection direction) (; Since three white pixels are lined up, its peripheral value is W3. The connected peripheral pixels in the third row and third column are black pixels, and two black pixels are lined up in the horizontal direction. , its peripheral value is B 2.

Based on the peripheral values of 1-, consider the no; turn connection law between adjacent unit meshes of 1-]. Here, the Z-turn connection law is as follows (the connection law between individual connected peripheral pixels adjacent in the connection direction, the connection law between connected peripheral pixel groups adjacent in the connection direction, and the connection law between twisting unit meshes). Connection Law (Think of it in two parts.

(1) Connection law between adjacent individual pixels (acceptable connection conditions) In the connection between two pixels of the same type (black-black, white-white) in P1 connection, the sum of the peripheral values (k) of both pixels is (n -1) That's all.

P2 connection: A connection between different types of pixels (black-white, white-black), where the peripheral value of each pixel itself (also the peripheral value of each pixel) is (n-1) or more.

However, it is assumed that n is the thickness of the line (digital line) of the two-dimensional pattern, and is larger than the size of one side of the unit mesh.

(11) Connection law between unit meshes S1 connection: If all adjacent pixels are Pi connections, this can be accepted as a legal connection.

S2 connection: A connection with two or more B2 connections. This connection is not acceptable if there are one or more white single-point connections on two or less sides (horizontally (two above and below, vertically: left and right) on both sides of the black-white connection).

S3 connection: A connection with one or more B2 connections. This connection is
The verification error value of at least one of the two pixels on both sides of a B2-connected black pixel (horizontally, top and bottom, vertically, left and right) is B1, or two pixels on both sides of a B2-connected white pixel It is unacceptable if the peripheral value of at least one pixel within is wl. In addition, if B2 is included, it is acceptable only if both 82° and 83 are satisfied.

1. Examples of application of the connection law in 1-1 are shown in FIGS. 4 to 6 (unit mesh size is 3×3 pixels).

In both figures, the pixels subjected to hunting are black pixels.

Looking at the horizontal connections between the four unit meshes A-D in Figure 4(a) (all of which are legal patterns), we can see that between individual pixels (two in Figure 40)) ( As shown in Figure 5(a), all are P1 connections and acceptable S1 connections.The lateral connections between the four unit meshes A-D in Figure 5(a) are as shown in Figure 5(1)). The P1 connection and B2 connection are mixed in the S2 connection, which is unacceptable.
), the lateral connections between the four unit meshes of A-D are:
As shown in FIG. 6(b), P1 connections and B2 connections coexist, which is an unacceptable S3 connection. Although vertical connections are not shown, they may be applied in the same way.

In order to confirm the validity of the connection law stated in Section 7, the following (
Two experiments were conducted as shown below.

In other words, CCI TT's facsimile test chart) Nll (English letter) high quality manuscript, contaminated manuscript,
Each of the blurred originals was mechanically divided into two unit meshes of 3 x 3 pixel size to obtain two-dimensional pattern information (binary). From this two-dimensional pattern information, symbols consisting only of legal patterns were obtained. A notation image was generated. However, as legal patterns, 66 types of legal patterns shown in the specification and drawings attached to the above-mentioned patent application were used.

1- symbol notation image (=, 81.82,
The total number of vertical and horizontal connections (referred to as legal connections) between legal patterns that satisfy only the acceptable conditions for 8;3 connections (no unacceptable S2 connections or S3 connections) were investigated. In addition, the ratio of legal connections in each direction to the total number of connections (450, 225) was determined. Furthermore, among the legal connections, the number of white-white connections (the number of connections between all-white unit meshes),
We investigated the ratio of the number of connections excluding this. These values are shown in Table 1.

Table 1 As can be seen from Table 1, in high-quality manuscripts, the cumulative number of legal connections is 99.7% or more of the total number of connections. Even if the most frequent white-white connection is excluded, the ratio is still over 96 chis. This ratio is lower for contaminated manuscripts or manuscripts with "'"
The cumulative ratio was around 82% for dirty manuscripts, and around 85% for faded manuscripts. Therefore, these ratios determine the condition of the target image (good quality, contamination, blur).
Can be used as one parameter.

On the other hand, in the case of 66 types of legal patterns, the number of possible legal connection types in each direction is 1582, and the number of possible connection types in each direction is 662 = 4356, which is approximately 36.3.
%Met. Furthermore, the number of combinations of legal patterns in which four unit meshes are legally connected simultaneously in both the vertical and horizontal directions as shown in Figure 1 was 384.562, which was 2.03% of the total number of combinations of 664. . This is one proof that there is a strong constraint that the object is a set of digital lines even between unit meshes.

If we comprehensively evaluate the above matters, the above-mentioned "Sl.

82.83 “satisfies only the acceptability conditions for the connection”
It can be concluded that the connection between adjacent unit meshes is valid as a pattern connection condition for legal acceptance.

Next, a process of converting a symbol notation image into a legal symbol notation image using the above pattern connection conditions will be described.

In Figure 7, any one unit mesh on the symbol notation image (the degree mesh with hunting in the figure)
If we pay attention to this unit mesh 7, this unit mesh 7 of interest is connected to eight surrounding unit meshes.

In other words, the attention unit mesh is the 4
The connection relationships between unit meshes are (a), (o), and (c).

There are 4 pairs.

Therefore, in order to determine whether the current pattern (legal pattern) of the unit mesh of interest is valid in relation to the patterns of the surrounding unit meshes, basically It is necessary to observe the connection relation l of the set. If there is an unacceptable connection relationship that does not meet the pattern connection conditions for even one set, the mesh of the unit of interest or its adjacent unit mesh (for example, the mesh of the unit of interest marked with a check directly above the mesh of the unit of interest) If the relationship is not acceptable, convert the pattern (either one of the diagrams) to another legal pattern, and make corrections so that all four sets become acceptable legal connections. Because this modification may cause other connectivity relationships that include the modified unit mesh to become unacceptable, the connectivity relationships are rechecked and modified as often as necessary. In this way, a symbol notation image can be converted into a legal symbol notation image.

The basic conversion processing procedure has been described above, but this can be simplified as described below.

Generally, images are processed while scanning them.

In rask scanning, main scanning is generally performed from left to right, and sub-scanning is performed from top to bottom.

Therefore, when performing real-time processing, it is preferable to perform the processing according to the following procedure in accordance with the progress of scanning.

Suppose now that in the 8th V, the unit mesh E to which )-touching has been applied is read. At this point, the surrounding unit meshes A, B, C, and D have completed the conversion process to the symbol notation image and the conversion process from the symbol notation image to the legal/indication image.

Check the pattern of the unit mesh E that you are interested in,
In the case of an illegal pattern, first convert it to a legal pattern (conversion process to a symbol notation image), and then immediately execute the following processing steps (2), otherwise (1).

[Step]

Unit mesh A, r3. The connection relationship between D and E and the connection relationship between unit meshes B, E and C are observed to check whether they are acceptable and satisfy the pattern connection conditions described above.

[Step 2] If both connections are acceptable, the conversion process to the unit mesh E (two pairs of legal symbol notation images) is completed. If one or both connections are unacceptable,
The .zeta.-turn of the unit of interest, :I:E, is modified to another legal pattern so that both connections can be accepted, and the process is terminated.

In addition, it is legal to accept both connections; there are 2 turns.
If there are more than one mesh pattern, the mesh pattern is selected by considering, for example, the distance from the unit mesh pattern before modification.

The reason why the connection relationship can be made acceptable only by modifying the .; turn of the mesh E of the unit of interest is as follows.

At the time of processing the unit mesh E of interest, the unit mesh A,
Connections between D, between A and I'3, and between B and D have been checked. Therefore, if the connection between unit meshes A, B, D, and B is unacceptable, the connection can be made acceptable simply by modifying the pattern of unit mesh E. Similarly (2. Even if the connection between unit meshes B, E, and C is unacceptable, the connection between unit meshes 718 and 0 has already been checked, so the connection can be accepted only by modifying the pattern of the unit of interest mesh E. Possible (two possible)

Incidentally, although real-time processing is assumed here, it goes without saying that the conversion process to the legal symbol notation image may be performed after the symbol notation image is generated for the entire two-dimensional pattern to be processed.

As detailed above, the two-dimensional pattern correction method according to the present invention corrects the pattern by checking not only the pattern of each unit mesh but also the connection relationship between adjacent unit meshes and between pixels. It is possible to effectively (correct and restore) a 2D pattern with noise or distortion into a high quality 2D pattern.Also, as is clear from the above, it does not require a large capacity buffer memory. It is also easy to process in real time with just one image scan.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining the connection of unit meshes, Figure 2
The figure is a diagram for explaining the definition of peripheral pixels of a unit mesh, Figure 3 is a diagram illustrating peripheral values of a unit mesh, and Figures 4 to 6 are examples of horizontal connections between adjacent unit meshes. Figure 7 is a diagram for explaining the basic conversion process from a symbol representation image to a legal symbol representation image, and Figure 8 is a diagram for explaining a more practical two-dimensional pattern correction process. It is a diagram. Agent Patent Attorney Makoto Suzuki Figure 1 Figure 2 (L) (b) (Figure 3 Figure 4 (b) Figure 5 Figure 7 Figure 8 Procedural amendment (voluntary) Collection Seal 11 (Gold button 0 yen December 22, 1981 Commissioner of the Japan Patent Office Shima 1) Haruki Tono 1°”] Table of items Patent Application No. 109766/1982 2. Name of the invention 2-dimensional pattern correction Form 3, Person making the amendment/Relationship with one case Applicant address: 158-4 Nasahara Motomachi, Takatsuki City, Osaka Prefecture, Agent @151 Address: 2-38-12 Yoyogi, Shibuya-ku, Tokyo
Line Department Building 201Q Name (7376) Patent Attorney Makoto Suzuki Telephone 03 (374) 9671
No. 5 Number of inventions increased by amendment None 6, "Detailed explanation of the invention" column 7 of the specification subject to amendment, Contents of amendment (1) 1st peripheral value in the fourth line from the bottom of page 8 of the specification. Correct to "peripheral value". (2) Change “2 or less” to 1 on page 11, line 5 of the specification.
Correct to 2 or less. (The statement on page 11, lines 14 to 17 of the 31 Specification is corrected as follows. "It is unacceptable when the peripheral value of one pixel is Wl. In other words, it is unacceptable when P2 is included. S2.8 when possible
3. Only when both conditions are met. ”14) Akirat @ second 15th
For the first unit of attention mesh 2 on the 12th line of the page, "" is corrected to "with respect to the unit of interest mesh."

Claims (1)

[Claims] 1. A specific pattern among unit mesh patterns appearing in a two-dimensional pattern is selected in advance as a legal pattern, and the legal patterns that are allowed to exist adjacent to each other are satisfied. Specific pattern connection conditions that must be processed are determined in advance, and when a unit mesh of an illegal pattern other than a legal pattern appears in the two-dimensional pattern to be processed, that illegal pattern becomes one legal pattern that has a specific relationship with it. , and the pattern connection relationship between adjacent unit meshes on a two-dimensional pattern that has completed the conversion process or is in the process of conversion process is observed, and the specific pattern connection condition described above is not satisfied. By converting the pattern of the unit mesh of one of the adjacent unit meshes into another legal pattern so that A two-dimensional pattern modification method characterized by generating a two-dimensional pattern consisting of. 2. The two-dimensional pattern correction method according to claim 1, characterized in that the illegal pattern is converted into a legal pattern selected according to the distance between the illegal pattern and the illegal pattern. 36. The two-dimensional pattern correction method according to claim 1, wherein the pattern connection condition is defined with respect to adjacent unit meshes and between individual pixels. 4. Assuming that the two-dimensional pattern is main-scanned from left to right and sub-scanned from the second to the bottom, regarding the unit mesh of interest and the unit meshes adjacent to the left, directly above, diagonally above the left, and diagonally to the right L. Claim 1: Observing the pattern connection relationship, and converting the pattern of the unit mesh of interest so that the specific pattern connection condition is satisfied between all of the unit meshes. Two-dimensional pattern correction method described in Section 2.