JP2802183B2 - Inspection apparatus using pattern matching and pattern matching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern matching method in an image processing apparatus, and more particularly to a pattern matching apparatus suitable for quality inspection of stamped characters and ink jet characters.

[0002]

2. Description of the Related Art As disclosed in Japanese Patent Application Laid-Open No. 1-229384, a conventional pattern matching apparatus includes an n-row m-column master pattern which is character information of a character registered in advance, and an actual input pattern. The difference information is extracted by comparing it with the input pattern of n rows and m columns, which is the character information of the extracted character, and the characters are collated based on the number of difference information.

A major obstacle to quality inspection of stamped characters and ink-jet characters using such a pattern matching apparatus is not only when a character different from the originally intended character is printed, but also when a character different from the originally intended character is printed. Even if the same character as the intended character is printed, if the character width becomes thicker or thinner depending on the ink, stamp, and the state of the side to be printed, the input pattern that is the character information of the character is registered in advance. This means that the number of difference information obtained as a result of comparison with the master pattern which is the character information of the original character is increased. Such difference information is characterized in that it occurs in a contour portion of a character.

Therefore, conventionally, the difference information of the contour portion of the character which is likely to be generated in the comparison between the master pattern and the input pattern is ignored.

More specifically, the master pattern is composed of three elements, a background element, a character element, and an uncertain element, and the uncertain element indicates an area of a character outline. Then, the number of pieces of difference information in the uncertain element is corrected so as to be smaller than the actual value.

[0006]

In the above-mentioned prior art, since the area of the outline of a character in the master pattern registered in advance is set as an uncertain element, the information amount of the character element which should be the original character information is reduced. As a result, there is a problem that the number of pieces of difference information for determining whether or not the character is the corresponding character finally depends on the information amount of the character element.

In the prior art, in order to cope with a case where characters actually printed become thicker and thinner,
It is necessary to predict the fluctuation range of the character and secure an uncertain element corresponding to the fluctuation, and there is a problem that the uncertain element increases.

It is an object of the present invention to provide a master pattern
Without reducing the information amount of the character element which should be the original character information, regardless of the direction of the fluctuation of the character actually printed, from among the difference information obtained as a result of comparing the master pattern and the input pattern, It is to remove only the difference information of the outline part of the character.

[0009]

In order to achieve the above object, according to the present invention, a master pattern does not include an uncertain element, and difference information generated in a contour portion (uncertain element) of a character is removed. Filter processing to be performed.

More specifically, a memory storing a master pattern, which is character information of characters registered in advance, and an input pattern, which is character information of characters actually input, is stored in the memory. A sampling circuit that samples the master pattern and the input pattern into a matrix of n rows and m columns; a comparison circuit that extracts difference information between the master pattern matrix and the input pattern matrix sampled by the sampling circuit; A filter that removes only difference information occurring in the outline portion of the character from the difference information, and a counter that measures the number of remaining difference information excluding the portion removed by the filter and outputs a measurement result. Is provided.

The filter is a matrix shifter for shifting the difference information extracted by the comparison circuit up, down, left and right, each of the four difference information shifted up, down, left and right by the matrix shifter, and extracted by the comparison circuit. A matrix AND circuit for performing an AND process between the difference information and the matrix A
Between each of the results of the AND processing by the ND circuit, O
And a matrix OR circuit for performing R processing.

The shift amount of the matrix shifter can be arbitrarily changed.

[0013]

The difference information between the master pattern matrix of n rows and m columns and the input pattern matrix of n rows and m columns extracted by the comparison circuit is called a comparison pattern matrix.

In the filter, specifically, the matrix shifter shifts the comparison pattern matrix to the upper left, shifted to the upper left, shifted to the upper right, shifted to the upper right, shifted to the lower left, shifted to the lower left, shifted to the lower right. Generate a lower right shift matrix.

Next, in the matrix OR circuit, the matrix AND circuit performs an AND operation between the upper left shift matrix and the comparison pattern matrix.
An intermediate matrix is generated by performing an OR process between the result of the process and the result of the AND process performed between the upper right shift matrix and the comparison pattern matrix by the matrix AND circuit.

Subsequently, the matrix OR circuit determines whether the matrix AND circuit performs an AND operation between the lower left shift matrix and the intermediate matrix, and the matrix AND circuit determines whether the lower right shift matrix and the intermediate matrix have the same. The result pattern matrix is generated by performing an OR process on the result of the AND process.

In the comparison pattern matrix, when the input pattern is character information of a character different from the original character, a lot of difference information is generated in different portions, but the input pattern is the same character as the original character. Even in the case of character information, difference information is generated in a contour portion of the character due to a change in an external factor such as a printing state.

The present invention focuses on difference information when different character information is compared and difference information when the same character information is compared. Difference information generated in a contour portion of a character by a filter is provided. Is removed, thereby preventing a malfunction due to a change in an external factor such as a printing state.

That is, the variation within the range of the shift amount by the matrix shifter is caused by the AND processing of the matrix AND circuit and the matrix O
Since it is absorbed by the OR processing of the R circuit, if the input pattern is character information of the same character as the original character,
Even if there is a fluctuation, the number of difference information can be minimized,
When the input pattern is character information of a character different from the original character, the number of difference information can be maximized even if the input pattern is similar to the master pattern.

Further, noise information generated at the time of sampling by the sampling circuit can be removed as a result.

The fluctuation range to be absorbed can be adjusted by changing the shift amount of the matrix shifter.

[0022]

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

FIG. 1 is a block diagram showing a configuration of a pattern matching apparatus according to one embodiment of the present invention.

In the figure, 1 is a memory, 2 is a sampling circuit, 3 is a comparison circuit, 4 is a filter, and 5 is a counter.

As shown in FIG. 2, the memory 1 stores a master pattern memory 1a for storing a master pattern which is character information of characters registered in advance, and stores an input pattern which is character information for characters actually input. And an input pattern memory 1b.

FIG. 3 is an explanatory diagram of the sampling process performed by the sampling circuit 2.

As shown in FIG. 3, the sampling circuit 2
Converts the master pattern stored in the master pattern memory 1a into a master pattern matrix 6a, and converts the input pattern stored in the input pattern memory 1b into an input pattern matrix 6b. The master pattern matrix 6a and the input pattern matrix 6b generated by the sampling circuit 2 are n rows and m columns.

FIG. 4 is an explanatory diagram of the comparison processing performed by the comparison circuit 3.

As shown in FIG. 4, the comparison circuit 3 extracts difference information between the master pattern matrix 6a of n rows and m columns generated by the sampling circuit 2 and the input pattern matrix 6b, and compares n rows and m columns. A pattern matrix 6c is generated.

The difference information forming the comparison pattern matrix 6c includes uncertain element difference information 7 and mismatch element difference information 8. The uncertain element difference information 7 is difference information that occurs in the outline portion of the character, such as noise generated when an input pattern is input or when the sampling circuit 2 performs sampling. Also,
The mismatch element difference information 8 is difference information generated in a part where the input pattern and the master pattern are essentially different.

FIG. 4A shows a case where the master pattern is “3” and the input pattern is “8”. Therefore, in addition to the uncertain element difference information 7, Information 8 has also been generated.

On the other hand, FIG. 4B shows a case where both the master pattern and the input pattern are "3", so that only the uncertain element difference information 7 is generated.

FIG. 5 is a block diagram showing the internal configuration of the filter 4.

In the figure, 4a is a matrix shifter, 4b is a matrix AN
D circuits and 4c are matrix OR circuits.

FIG. 6 is an explanatory diagram of the filtering process performed by the filter 4.

As shown in FIG. 6, the filter 4 includes a comparison pattern matrix 6 of n rows and m columns generated by the comparison circuit 3.
For c, the uncertainty element difference information 7 is removed, and a result pattern matrix 6d of n rows and m columns composed of only the unmatched element difference information 8 is generated. The counter 5 measures the number of pieces of mismatch element difference information 8 in the result pattern matrix 6d of n rows and m columns generated by the filter 4, and outputs the measurement result.

Hereinafter, the filtering process performed by the filter 4 will be described in detail.

The matrix shifter 4a includes an upper left shift matrix 6e obtained by shifting the comparison pattern matrix 6c of n rows and m columns generated by the comparison circuit 3 to the upper left, an upper right shift matrix 6f shifted to the upper right, and a lower left shift matrix shifted to the lower left. 6g, a lower right shift matrix 6h shifted to the lower right is generated. This is shown in FIG.

Next, the matrix AND circuit 4b performs an AND process between the upper left shift matrix 6e and the comparison pattern matrix 6c, and performs an AND process between the upper right shift matrix 6f and the comparison pattern matrix 6c. The matrix OR circuit 4c has two A
The result of the ND processing is OR-processed, and an intermediate matrix 6i of n rows and m columns
Generate

Subsequently, the matrix AND circuit 4b performs an AND process between the lower left shift matrix 6g and the intermediate matrix 6i,
An AND process is performed between the lower right shift matrix 6h and the intermediate matrix 6i. The matrix OR circuit 4c performs an OR process on the results of the two AND processes, and generates a result pattern matrix 6d of n rows and m columns. This is shown in FIG.

Since the uncertain element difference information 7 in the comparison pattern matrix 6c, which is the difference information between the master pattern matrix 6a and the input pattern matrix 6b, occurs in the outline portion of the character,
Thus, the unmatched element difference information 8 is a block connected in four directions.

Thus, as described above, the comparison pattern matrix 6c, which is the difference information between the master pattern matrix 6a and the input pattern matrix 6b, and the shift matrices 6e to 6h obtained by shifting the comparison pattern matrix to the upper left, lower left, upper right, and lower right. By performing an AND process between them, the linear difference information (that is, the uncertain element difference information 7) is removed, and the massive difference information element (that is, the mismatch element difference information 8) has its original size. It remains in the result pattern matrix 6d without being changed.

That is, for example, when the input pattern is character information of a printed character, uncertain element difference information 7 which is difference information generated when the actually printed character becomes thicker or thinner. Is removed from the comparison pattern matrix 6c by performing such a filtering process, but the mismatched element difference information 8 which is difference information generated when a character actually printed differs from a registered character. Are not removed from the comparison pattern matrix 6c.

The uncertain element difference information 7 to be removed can be adjusted by adjusting the shift amount of the matrix shifter 4a.

That is, for example, when a character actually printed becomes thicker or thinner, a change in the thickness within the range of the shift amount is removed as the uncertain element difference information 7. Is adjusted, the variation of the thickness exceeding the range of the shift amount can be included in the mismatch element difference information 8.

Next, the measurement processing of the counter 5 will be described.

The counter 5 counts the number of remaining mismatch information difference information 8 from the result pattern matrix 6d from which the uncertain element difference information 7 has been removed, and obtains the result. Then, the ratio of the matching portion to the area of the master pattern is calculated, and the calculated ratio is compared with a predetermined value to output whether or not there is an error.

As described above, according to the present embodiment,
Uncertain elements are not included in the master pattern, and only the uncertain element difference information 7 is removed from the comparison pattern matrix 6c obtained as a result of comparing the master pattern matrix 6a with the input pattern matrix 6b. Since the pattern matrix 6d is extracted as a result of leaving only the information 8, when the same character information is compared, it is hardly affected by a change in the thickness or a change in the printing state. Has the effect that it can be detected strictly.

Specifically, conventionally, since an uncertain element is included in a master pattern, the information amount of one master pattern is, for example, 16 (rows) × 16 (columns) in the case of 16 rows and 16 columns. ) × 3 (bits) = 768 (bits), and 36 × 768 (bits) = 27648 (bits) are required to correspond to 36 alphanumeric characters. The three bits in the above equation are the background element,
This is flag information for indicating whether the element is a character element or an uncertain element.

However, in this embodiment, since the master pattern does not include an uncertain element, flag information for indicating whether the element is a background element, a character element, or an uncertain element is unnecessary, and one master pattern is used. The information amount to be provided is 16 (rows) × 16 (columns) = 256 (bits).

Conventionally, in the case of 16 rows and 16 columns, the total number of elements as a result of sampling is 256 elements, and if the background element is 50%, the uncertainty element is 64 elements,
Although half of the character elements become uncertain elements, in this embodiment, since the master pattern does not include uncertain elements,
As compared with the prior art, twice the detection sensitivity can be realized.

Further, conventionally, when the same character information in 16 rows and 16 columns is compared, the fluctuation width that can be permitted to be the same is a fluctuation width of half a pixel corresponding to noise at the time of sampling ±. In this embodiment, if the shift amount of the matrix shifter is one pixel, the shift range of the two pixels is ± 12.5%, which is a range of ± 12.5%. There is a 4 times effect.

Next, an example of an inspection apparatus to which the present embodiment is applied will be described.

FIG. 9 is a block diagram showing a configuration example of an inspection apparatus to which the present embodiment is applied.

As shown in FIG. 9, the present inspection apparatus uses the date and product number printed by the inkjet printer 9 on the inspection object 12 moving at a high speed on a belt
An image is captured by a V camera (industrial camera) 10 and the captured data is processed by the pattern matching device 11 of the present embodiment.
Check that the date and product number printed are correct.

That is, in the pattern matching device 11, the date and product number to be originally printed are registered in the master pattern memory 1a.
Pattern matching is performed with the data captured in step (1).
When the measurement result of the counter 5 indicates that an incorrect date or product number is printed, the buzzer (not shown) is sounded, for example, to notify the inspector. Further, a device for removing the inspection object 12 on which the incorrect date or product number is printed from the belt conveyor may be provided.

In addition, the present embodiment can be applied to an inspection device for inspecting characters engraved on a key top and an inspection device for inspecting a bar code.

In this specification, characters, symbols,
“Character” is described as data representing a target object for pattern matching, such as a figure.

[0059]

As described above, according to the present invention,
Since the master pattern does not include uncertain elements, only the difference information generated in the outline of the character can be removed from the difference information obtained as a result of comparing the master pattern with the input pattern, so that the variation of the input pattern can be reduced. , It is possible to realize a highly sensitive pattern matching apparatus that extracts only the difference information that is essentially different regardless of the direction.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a pattern matching apparatus according to an embodiment.

FIG. 2 is an explanatory diagram illustrating a configuration of a memory according to the embodiment;

FIG. 3 is an explanatory diagram of a sampling process performed by the sampling circuit according to the embodiment.

FIG. 4 is an explanatory diagram of a comparison process performed by the comparison circuit according to the embodiment.

FIG. 5 is a block diagram illustrating an internal configuration of a filter according to the embodiment.

FIG. 6 is an explanatory diagram of a filtering process performed by the filter according to the embodiment.

FIG. 7 is an explanatory diagram of a shift process performed by the matrix shifter according to the embodiment.

FIG. 8 illustrates a matrix AND circuit and a matrix OR according to the present embodiment.
FIG. 4 is an explanatory diagram of an AND process and an OR process performed by a circuit.

FIG. 9 is an explanatory diagram showing a configuration of an inspection device to which the pattern matching device of the present embodiment is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... memory, 1a ... master pattern memory, 1b ... input pattern memory, 2 ... sampling circuit, 3 ... comparison circuit, 4 ... filter, 4a ... matrix shifter, 4b ... matrix AN
D circuit, 4c matrix OR circuit, 5 counter, 6a master pattern matrix, 6b input pattern matrix, 6c comparison pattern matrix, 6d result pattern matrix, 6e upper left shift matrix, 6f upper right shift matrix, 6g ... Lower left shift matrix, 6h Lower right shift matrix, 6i Intermediate matrix, 7 Uncertain element difference information, 8 Unmatched element difference information, 9 Inkjet printer, 10 ITV camera, 11 Pattern matching device, 12 Inspected body.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-65377 (JP, A) JP-A-61-35303 (JP, A) JP-A-59-2330 (JP, A) JP-A-58-58 30645 (JP, A) JP 1-60767 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G06K 9/62 Patent file (PATOLIS)

Claims (5)

(57) [Claims] 1. A cell which is information of a character registered in advance.
Input that is the information of the character pattern and the characters actually input
Storage means for storing a pattern and a master pattern and an input stored in the memory
By sampling the pattern into an n-by-m matrix
The master pattern matrix and the input pattern matrix
The sampling means to be generated, and the master pattern matrix and the input pattern matrix are compared.
And the comparison pattern matrix, which is the pattern matrix of the difference between the two, is
Obtaining comparison means, and comparing the comparison pattern matrix with an upper left diagonal, an upper right diagonal,
Shift down and down diagonally right by a predetermined amount
Shifting means for generating the shifted four shift matrices, and two shift matrices among the four shift matrices.
Each of them is AND-processed with the comparison pattern matrix.
Processing results obtained by ND processing are ORed with each other.
Obtain an intermatrix, and replace the intermediate matrix with the four shift matrices
And the AND operation with the remaining two shift matrices
Then, the processing results obtained by the AND processing are ORed with each other.
Uncertainty from the comparison pattern matrix by processing
Filter means for obtaining a mismatched pattern matrix with elements removed
And count the number of information included in the mismatch pattern matrix
And a counter means for performing the pattern matching. 2. A pattern matching apparatus according to claim 1, wherein said filter means obtains said intermediate matrix.
Before AND processing with the comparison pattern matrix
As the two shift matrices, the shift means is an upper left diagonal.
And the shift matrix shifted to the upper right.
A pattern matching device using the shifted shift matrix . 3. A cell which is information of a character registered in advance.
Input that is the information of the character pattern and the characters actually input
Storage means for storing a pattern and a character to be inspected,
Input means for storing the input pattern in a memory
And the master pattern and input stored in the memory
By sampling the pattern into an n-by-m matrix
The master pattern matrix and the input pattern matrix
The sampling means to be generated, and the master pattern matrix and the input pattern matrix are compared.
And the comparison pattern matrix, which is the pattern matrix of the difference between the two, is
Obtaining comparison means, and comparing the comparison pattern matrix with an upper left diagonal, an upper right diagonal,
Shift down and down diagonally right by a predetermined amount
Shifting means for generating the shifted four shift matrices, and two shift matrices among the four shift matrices.
Each of them is AND-processed with the comparison pattern matrix.
Processing results obtained by ND processing are ORed with each other.
Obtain an intermatrix, and replace the intermediate matrix with the four shift matrices
And the AND operation with the remaining two shift matrices
Then, the processing results obtained by the AND processing are ORed with each other.
Uncertainty from the comparison pattern matrix by processing
Filter means for obtaining a mismatched pattern matrix with elements removed
And count the number of information included in the mismatch pattern matrix
An inspection apparatus comprising: 4. An input pattern which is information of characters actually input.
The first step is to sample the turns into a matrix of n rows and m columns.
And-up, the input pattern registered in advance in which the master pattern matrix
Pattern matrix, and the
A second step of obtaining a comparison pattern matrix;
Turn matrix, diagonally up left, diagonally up right, diagonally down left, diagonally right
To shift downward by a predetermined amount
, A third step of generating four shift matrices
And two shift matrices of the four shift matrices
Each of them is AND-processed with the comparison pattern matrix.
Processing results obtained by ND processing are ORed with each other.
Obtain an intermatrix, and replace the intermediate matrix with the four shift matrices
And the AND operation with the remaining two shift matrices
Then, the processing results obtained by the AND processing are ORed with each other.
A fourth step of processing to obtain a mismatched pattern matrix, and counting the number of information included in the mismatched pattern matrix
And a fifth step of performing
Matching method . 5. The pattern matching device according to claim 4,
In the third step, the intermediate matrix is obtained.
In order to perform AND processing with the comparison pattern matrix,
In the third step, the two shift matrices
Shift matrix shifted to the upper left and diagonally to the upper right
Characterized by using a shift matrix shifted in
Pattern matching method .