JPH0769933B2 - Standard character pattern creation device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a standard character pattern creating apparatus, and more particularly to a standard character pattern creating apparatus for a character recognition apparatus that reads characters using an imaging means and recognizes the characters.

[Prior Art] Stamped characters are resistant to aging, and their readability is not lost even in an environment where they are easily soiled. Therefore, it is widely used as a character that gives important information for production instructions and management in various production processes.

In particular, in the production process of automobiles, it is widely used to write a unique number to each component constituting the vehicle body, engine, and the like.

For this reason, various types of character recognition devices have been proposed in the past, and such a conventional device uses an ITV camera or the like to capture an image of the engraved character portion and output a grayscale image of each of the grayscale images. Convert pixel information to binary data,
It is formed to detect each character from the binary image data.

Then, the unknown character pattern detected in this way is sequentially overlapped with the standard character pattern registered in advance and compared to perform pattern matching, and characters are recognized based on the degree of coincidence or similarity between the two.

However, it is difficult to control so that the stamping conditions are always the same with a stamping machine that is widely used at present, and the groove depth varies for each stamped character. Therefore, in a so-called engraved character image, the character line width often varies as a whole even for the same kind of character.

In addition, when the number of digits of the character to be recognized is large, for example, when the number of digits of the character is large, such as the vehicle body number, the angle and direction of the groove of each character with respect to the illumination are uneven. Therefore, in a so-called engraved character image, the character line width is partially uneven.

Furthermore, if the engraved characters are painted after being stamped, unevenness will occur around the characters due to uneven coating or uneven adhesion of paint around the engraving grooves, and the unevenness will cause the characters themselves to deform. . Therefore, when an engraved character on a painted surface is imaged, the entire line width of the character part changes or the line width partially differs, resulting in a character outline with a lot of unevenness, and even with the same character width. It often presents a character pattern.

Therefore, as in the conventional device, even if the detected unknown character pattern and the standard character pattern registered in advance are simply pattern-matched, the imprinted character may not be accurately recognized for the various reasons described above. There was a problem that there were many.

In order to solve such a problem, JP-A-57-103582
The technology disclosed in Japanese Patent Laid-Open No. 57-103583 is known.

In this conventional technique, a plurality of standard character patterns corresponding to the variations are prepared and pattern matching is performed in order to cope with variations in the character image at the time of engraving a stamped character or at the time of imaging.

However, this makes it necessary to prepare a large number of standard character patterns in response to various deformed character patterns such as those on a painted surface.

Therefore, this conventional technique has a problem in that the memory requirement required to register the standard character pattern increases and the processing time for pattern matching increases.

Further, as another conventional technique, a technique is proposed in which the threshold used when converting a grayscale image of a stamped character into binary image data is changed to bring the character line width of the unknown character pattern closer to the character line width of the standard character pattern. Is being done.

For example, the technology disclosed in JP-A-61-208178,
Proceedings of 6th General Conference of the Institute of Electronics and Communication Engineers, 1985, 6-15
Such a technique is disclosed on page 3.

However, even when used in such a conventional technique, when recognizing an engraved character on a painted surface, in order to prepare for when the character line width is partially different or when the character contour has irregularities, It is necessary to prepare multiple standard character patterns for each character.

Therefore, there is a problem in that the memory capacity required for registering the standard character pattern increases, and the marking character cannot be recognized quickly.

[Problems to be Solved by the Invention] The present invention has been made in view of such a conventional problem, and an object thereof is to provide a character whose line width varies wholly or partially and a contour shape. Characters that are not slippery and have many irregularities,
In particular, it is an object of the present invention to provide a newly developed standard character pattern creating device for a character recognizing device, which is capable of accurately and quickly recognizing an engraved character on a painted surface.

[Means for Solving Problems] In order to achieve the above-mentioned object, the standard character pattern creating apparatus of the present invention, as shown in FIG. 1, has a plurality of binary values under different conditions for each character type. A character pattern detection means for obtaining a character pattern of an image and a plurality of binary image character patterns obtained for the same character type are accumulated to obtain a frequency distribution of whether each pixel of the character pattern is a character portion or a background portion. A cumulative pattern creating unit that creates a cumulative pattern that represents, an average character pattern creating unit that creates an average pattern of a plurality of character patterns by extracting a part that frequently becomes a character part from the cumulative pattern, and the average An outline shape that creates a frame that circumscribes the character pattern and calculates the distance coordinate series from each side of the circumscribed frame to the outline of the character as the outline shape of the character for each side. Comparing means and a similar character type selecting means for selecting a similar character type with respect to the character type of interest using the distance coordinate series of each side obtained from the outline shape creating means, and comparing the character type of interest and the outer shape of the similar character type. Then, the contour feature portion extraction means for extracting a coordinate section having a large difference between the two as a feature portion, and the coordinate series representing the contour shape of each side obtained by the contour shape creation means is smoothed to obtain a smooth contour shape. An outline shape smoothing unit that creates a coordinate series as a standard character pattern, a range indicating the outline shape feature obtained by the outline feature extraction unit, and a standard character pattern obtained by the outline shape smoothing unit. A storage memory that stores each of the character types as a set, and a coordinate series that indicates the smoothed outer shape stored in the storage memory. Using the range that represents the sign part, the character type of interest and other character types are compared by pattern matching while adding an appropriate load to the coordinate series of the range that represents the feature part, and the differences between the coordinate series are compared to all coordinates. The distance calculation condition determining means for determining the value of the load so that the distance difference is maximized, and the distance calculation condition determining means. The value of the load applied to the range indicating the obtained characteristic portion and the range indicating the characteristic portion stored in the storage memory are used as the calculation conditions, and the calculation condition and the standard stored in the storage memory are set for each character type. And a standard pattern creating means for outputting in combination with a character pattern.

Here, the outer contour shape creating means creates a rectangular frame circumscribing the average character pattern, and sets a pair of left and right coordinate series representing the distances from the left and right sides of the circumscribed rectangular frame to the character contour to the outer shape of the character for each side. Is preferably calculated as

Further, the character pattern detection means includes an image pickup means for reading a character, and a character detection section for cutting out a character pattern from the read image data, and the character detection section converts the read image data into binary image data. A binary image forming means for outputting, a character detecting / cutting out means for cutting out a pattern of each character from the binary image data with a predetermined circumscribing frame, and a normalization for outputting the position and size of the cut out character pattern by emulating It is preferable that the means is formed to include

Further, it is preferable that the character detection unit is formed to have an expansion / contraction circuit that performs expansion / contraction processing on the binary image data, removes isolated pixel data that becomes noise, and outputs it to the character detection / cutout unit.

[Operation] The present invention is configured as described above, and the operation will be described below.

The apparatus of the present invention first obtains the character pattern of the binary image for each character type by using the image pattern detection means. At this time, under different conditions, for example, the embossing pressure and the embossing position of the engraved character, the way of lighting at the time of imaging, and the value of the binarization threshold value are changed, and a plurality of binary image characters for the same character type are changed. Get the pattern.

Next, the cumulative pattern creating means accumulates a plurality of binary character patterns obtained for the same character type, and creates a cumulative pattern representing a frequency distribution of whether each pixel of the character pattern is a character portion or a background portion. create.

Next, the average character pattern creating means extracts a part having a high frequency of becoming a character part from the accumulated pattern, and creates an average character pattern of a plurality of character patterns obtained under different conditions for the same character type.

Then, the outer contour shape creating means creates a frame circumscribing the average character pattern, obtains a coordinate series representing the distance from each side of the circumscribing frame to the contour of the character, and the distance to each side thus obtained The coordinate series is the outer shape of the character.

Next, the similar character type selecting means selects a similar character type for the focused character type using the distance coordinate series representing the external shape of each side obtained from the outer shape creating means.

Then, the outline feature portion extraction means compares the outline shapes of the character type of interest and the similar character type, and extracts a coordinate section having a large difference in distance coordinates between the two as a feature portion.

On the other hand, the outer shape smoothing means smoothes the coordinate series representing the outer shape of each side obtained by the outer shape creating means,
Create a smooth outline coordinate series as a standard character pattern.

The coordinate series of the standard character pattern thus obtained is stored in the storage memory for each character type as a set with the range showing the outline shape feature obtained by the outline feature extraction means. .

Next, the distance calculation condition determining means uses the coordinate series indicating the smoothed outer shape and the range representing the characteristic section of the coordinate series to perform pattern matching between the character type of interest and the other character types to determine the characteristic part. Appropriate weight is added to the coordinate series in the range shown, the differences between coordinate series are summed over all coordinate series, and the total value is weighted averaged by the number of coordinate series to obtain the distance difference. . In this way, the distance differences of all other character types with respect to the character type of interest are calculated, and the minimum distance difference among them is obtained. This calculation is repeated while changing the load value to calculate the minimum distance difference with respect to the variable load value. Then, the load value is determined so that the minimum value of the distance difference is the maximum.

Then, the standard pattern creating means sets the value of the load thus obtained and the range indicating the characteristic portion stored in the storage memory as a set of calculation conditions, and for each character type, the calculation condition and the The standard character pattern stored in the storage memory is output.

Therefore, if the standard character pattern and the operation condition thus obtained for each character type are registered in, for example, the standard pattern memory of the character recognition device, the unknown character pattern can be accurately and quickly performed as follows. You can

That is, an unknown character pattern is created in the same manner as the standard character pattern from a binary image of unknown characters photographed using the image pickup means. Then, the unknown character pattern and each standard character pattern registered in the standard character pattern memory are sequentially compared while applying a load to the characteristic portion according to the calculation condition, and the pattern matching is performed from the circumscribed frame to the character outline. Calculate the weighted average value of the distance differences.

Here, the calculated weighted average value becomes the minimum value when the unknown character pattern and the standard character pattern match.

Therefore, by searching for the standard character pattern having the smallest weighted average value of the calculated distance differences, the character type of the unknown character pattern can be accurately determined.

The calculation of the weighted average value of the distance difference is preferably performed as follows.

That is, according to the operation conditions registered in the standard pattern memory in pairs with the standard character pattern, while adding a predetermined weight to the coordinate series of the range representing the feature part, the unknown character pattern and the standard character pattern are combined. The differences are summed over all coordinate series, and the value is weighted averaged by the number of coordinate series to obtain the difference α of the distance. At this time, if necessary, only the coordinate series of the range representing the characteristic part of the calculation condition is used, and the difference β of only the specific range is calculated in the same manner as the difference α.

The difference β thus obtained has a minimum value larger than the minimum value of the difference α when the unknown character pattern and the standard pattern do not match. Therefore, the character type determination means can determine the character type with higher accuracy using only the difference α or using the differences α and β.

Further, in the present invention, since the outer shape of the character is smoothed to create the standard character pattern, even for a character having a contour shape with many irregularities, only the main contour of the character is not affected by the irregularity. Can be extracted as a standard character pattern. Therefore, for example, even for a character having an irregular contour such as a character engraved on the painted surface, the character recognition can be performed with higher accuracy.

EFFECTS OF THE INVENTION As described above, according to the present invention, the coordinate series representing the distance from the circumscribing frame to the character contour is extracted as the standard character pattern representing the outer shape of the character. The amount of data of the extracted standard character pattern is extremely small as compared with the conventional technique that directly extracts the standard character pattern. Therefore, the data amount of the standard character pattern registered for pattern matching with the unknown character pattern can be greatly reduced. As a result, according to the present invention, the capacity of the standard pattern memory used for registering the standard character pattern can be greatly reduced, and further, the data processing time for recognizing the character can be shortened and the character recognition can be performed. It can be done quickly.

Moreover, if a rectangular frame circumscribing the average character pattern is created, and a pair of left and right coordinate series representing the distance from the left and right sides of this circumscribing rectangular frame to the character contour is obtained as the outer shape of the character for each side, the unknown character pattern is obtained. The data amount of the standard character pattern registered for pattern matching can be further reduced.

Further, according to the present invention, the range representing the characteristic portion of the standard character pattern and the weight value thereof are stored as the operation condition for character recognition forming a pair with the standard character pattern, and the pattern matching with the unknown character pattern is performed. The characteristic part is emphasized. Therefore, even if there is a similar character, the character can be accurately recognized.

Further, in the present invention, a standard character pattern is created by obtaining an average character pattern from a plurality of character patterns obtained with different conditions for the same character type. In addition to this, a standard character pattern is created by smoothing the outer shape of the character so that only the main contour shape of the character can be extracted without being affected by the unevenness of the character. Therefore, according to the present invention, it is possible to accurately recognize a character whose line width is wholly or partially changed, and moreover, the contour shape is not slippery and has many irregularities, especially on a painted surface. It is possible to more accurately recognize the stamped character of.

[Embodiment] Next, a preferred embodiment of the standard character pattern creating apparatus according to the present invention will be described with reference to the drawings.

FIG. 2 shows a preferred embodiment of a character recognition device to which the present invention is applied. In the drawing, a marking character A to be recognized is stamped on a frame 12 which is a component of a vehicle body of an automatic company. It is carved. The embossed character A is a 12-digit character string including, for example, alphanumeric characters and symbols.

The character recognition device 10 of the embodiment is for automatically reading the marking character A, and the marking character A is illuminated by the fluorescent lamp 14,
The image is taken by the TV camera 16. The engraved character A is perceived as a gray image in which the character part in the groove is dark and the surface part of the frame 12 is light.

Then, the character detection unit 100 cuts out the character image data from the read image data output from the TV camera 16, and selects the standard character pattern automatic creation circuit 200 and the character identification unit 300 according to the present invention via the line switching circuit 34. Output.

The standard character pattern automatic creation circuit 200 has a line switching circuit 3
Based on the character image data input via 4, create a coordinate series that represents the distance from the standard circumscribing frame of various characters to the character outline as a standard character pattern, and the range that represents the characteristic part of the standard character pattern and its load. The value is obtained as a calculation condition for character recognition that forms a pair with the standard character pattern.

Therefore, prior to the recognition of characters, the line switching circuit 34 is set on the standard character pattern automatic creation circuit 200 side, and various standard characters are imaged using the TV camera. A standard character pattern of a standard character and a calculation condition for character recognition, which is paired with the standard character pattern, are created and registered in the standard pattern memory of the character identification unit 300.

Further, the character identification unit 300 extracts the outer shape of the character as an unknown character pattern from the character image data input via the line switching circuit 34, and the unknown character pattern and the registered standard pattern are calculated according to the calculation conditions. Compare and determine the character type.

Therefore, after the standard character patterns of various standard characters and the calculation conditions for character recognition corresponding to the standard character patterns are registered in the standard pattern memory 42, the line switching circuit 34 is connected to the character identifying section 300.
When set to the side and shooting various engraved characters A with a TV camera, the character identification unit 300 automatically determines the type of the engraved character A based on the character image data input via the line switching circuit 34. It will be judged.

Character Detection Unit In the present embodiment, the output signal of the TV camera 16 input to the character detection unit 100 is converted into a digital value by the A / D conversion circuit 18 and stored in the first image memory 20.

The grayscale image data stored in the first image memory 20 is 2
The binarization circuit 22 binarizes the binarized image data based on a predetermined binarization threshold value and stores the binarized image data in the second image memory 24. At this time, in the binary image data, for example, the dark portion (character portion) of the grayscale image data is “1” and the light portion (background portion).
Is stored as “0”.

The binary image data stored in the second image memory 24 is subjected to contraction processing and expansion processing once by the expansion / contraction circuit 26, and then output to the character detection / cutout circuit 28.

As a result, it is possible to remove isolated pixel data that becomes noise (isolated "1" corresponding to noise other than "1" that constitutes a character), and pixel data that constitutes a character (of "1" Discontinuity of (pixel data) can be corrected.

Next, the character detection / cutout circuit 28 detects each character one by one from the binary image data of, for example, a 12-digit character string, and obtains a rectangular frame circumscribing the character for each detected character. Then, each detected character is cut out by the circumscribing rectangular frame, and binary image data (character pattern) for each character is output.

Next, the size normalization circuit 30 enlarges or reduces the character image in the circumscribed rectangle sum for each character so that the circumscribed rectangular frame of each cut out character has a predetermined standard size. And make the size of the character image constant.

Next, the position normalization circuit 32 calculates the center coordinates of the circumscribed rectangular frame, aligns the center coordinates with a predetermined alignment point, and aligns the aligned character image data (character pattern) via the line switching circuit 34. The standard character pattern automatic generation circuit 200 or the character identification unit 300 is selectively output.

Standard Character Pattern Automatic Creation Circuit FIG. 3 shows a preferred example of the standard character pattern automatic creation circuit 200 according to the present invention, and FIG.
A state in which a standard character pattern of the character type "5" is created using the standard character pattern automatic creation circuit shown in the figure is shown.

When operating the standard character pattern automatic generation circuit 200 of the embodiment, the line switching circuit 34 shown in FIG. 2 is set to the side of the broken line, and various conditions such as the marking position, the marking strength and the illumination are set. With some changes, a plurality of character image data (character patterns) with different conditions are obtained for the same character type. Then, it is input to the cumulative pattern creating circuit 50.

The cumulative pattern creation circuit 50 calculates the frequency of whether it is a character portion or a background portion for each pixel of character image data (character pattern) of the same character type, and creates a cumulative pattern that represents the frequency distribution. Image memory 52.

In FIG. 4A, for example, a cumulative pattern when the character type is “5” is simulated. In the figure, the area enclosed by the broken line is a character portion with a probability of 10% or more, and the area filled with black is the character portion.
% Or more area.

Next, the average character pattern creating circuit 54
The probability of becoming a character part from the cumulative pattern stored in 52
An area of 50% or more pixels is extracted to create an average character pattern, which is stored in the fourth image memory 56.

FIG. 4b schematically shows an average character pattern created for the character type “5”, for example.

Next, the outer shape creating circuit 58 creates a rectangular frame circumscribing the average character pattern stored in the fourth image memory 56. Then, horizontal scanning is performed from the left and right sides of the rectangular frame to the contour line of the character, the distances from the right and left sides to the contour line are obtained along each horizontal scanning line, and the coordinate series corresponding to the position of each side is created. To do. Then, the coordinate series of the right side and the left side thus obtained are stored in the fifth image memory 60 as the outer shape for the left side and the outer shape for the right side, respectively.

FIG. 4 shows a state in which a circumscribing rectangular frame i for the average character pattern b is created and a contour shape c for the left side and a contour shape d for the right side are created by taking the character type “5” as an example.

In this way, according to the apparatus of this embodiment, the coordinate series representing the outer shape of each character type is created and stored in the fifth image memory 60.

The similar character type selection circuit 62 compares the outer shape of the character type of interest and the outer shape other than the character type among the outer shape of each character type stored in the fifth image memory 60, and selects a similar character type.

That is, when the sum of the differences between the coordinate series indicating the outer shapes of the two over all coordinate series is smaller than a predetermined value, it is determined that the two are similar, and the similar character type is stored in the similar character type data memory 64. Remember.

At this time, a plurality of similar character types for the focused character type may be selected or no similar character type may be selected. For example, FIG. 4 shows a contour e on the left side of the character type “S” that is similar to the contour c on the left side of the character type “5”. In practice, the outer shape of both the left side and the right side is used, and similar character types are selected for all the character types and stored in the similar character type data memory 64.

Next, the outline feature portion extraction circuit 66 determines the left and right outline shapes (coordinate series) of the character type of interest stored in the fifth image memory 60 and the left and right outlines of the character type stored in the similar character type data memory 64. The outer shape (coordinate series) of is compared with the outer shape of the target character type to obtain a range that well represents the characteristics of the outer shape of the character type.

That is, after obtaining the difference between the coordinate series indicating the outer shape of the two over all coordinate series, the coordinate series of each side is divided into certain small sections, and the difference between the coordinate series of the two is calculated for each divided section. Find the sum. Then, all small sections whose total sum exceeds a predetermined value are picked up, ranked in descending order of value, and stored in the range storage memory 68 as a range indicating a characteristic part.

When there are a plurality of similar character types, the range indicating the characteristic part ranked for each character type is re-ranked and stored according to the frequency of each character type.

In FIG. 4, for example, for the character type “5”, the outer shape c
It is shown that a range in which the outer shape c is particularly different from the outer shape e, that is, a range f indicating a characteristic portion is obtained by comparing with the outer shape e of the similar character type “S”.

On the other hand, the outer shape smoothing circuit 70 smoothes the left / right outer shape stored in the fifth image memory 60, and stores the smoothed left / right outer shape as a standard character pattern in the storage memory.
The range is stored in the sixth image memory 72 in combination with the range indicating the characteristic part f stored in 68.

The smoothing method is performed by calculating an average value of a total of 5 points including two points before and after each point of the coordinate series indicating the outer shape and using the average value as the coordinate value of each point. For example, as for the character type “5”, FIG. 4 shows an outline shape g obtained by smoothing the outline shape c with respect to the left side.

Next, the distance calculation condition determining circuit 74 uses the sixth image memory 72.
Among the smoothed contour shapes stored in the above, between the contour shape of the character type of interest and the contour shape other than the character type, both character types are sequentially compared while applying a load to the range f indicating the feature of the contour shape. Pattern matching is performed, and the difference between the smoothed outer shape coordinate series is summed over all coordinate series. Then, the summed values are weighted averaged by the number of coordinate series, and the value is set as the distance difference α.

In this manner, α is calculated for all other character types of the character type of interest, and the minimum distance difference α is obtained.

Repeat this calculation while changing the value of the load,
Calculate the minimum distance α for each load value. Then, the value of the load at which the minimum value of the distance difference α is maximized is calculated,
The range indicating the load value and the characteristic portion is used as a calculation condition for calculating the distance.

If the minimum value α thus obtained does not exceed the predetermined threshold value, only the coordinate series of the range representing the characteristic part of the calculation condition is used, and the difference β of only the characteristic range is calculated in the same manner as the difference α. Calculate Then, the value of the load at which the minimum value of the distance difference β is maximized is obtained, and this load value and the range indicating the characteristic portion are used as the calculation conditions for calculating the distance.

That is, for the difference α, all the character types are taken into consideration, and the load value is obtained using the range other than the characteristic portion. Therefore, it may be difficult to determine the similar character type only by the difference α.

On the other hand, the difference β is effective for distinguishing the similar character type because the load value is obtained by using only the feature part in consideration of only the similar character type, and the load value is the load of the difference α. It is often different from the value.

Therefore, the difference α is sufficient for the dissimilar character type, but when there is a similar character type, it is preferable to add the difference β to the difference α and make the determination based on both values.

Therefore, the difference β may be obtained for similar character types as necessary.

Here, the load value is added to the range showing the characteristic part in the coordinate series showing the smoothed outer shape, but changes with respect to the coordinate series of the small sections ranked within the range showing the characteristic part. You may. For example, in FIG. 4, the range f indicating the characteristic portion of the smoothed outer shape g for the character type “5” is shown.
The load value h given to is illustrated.

In this way, the calculation condition for each character is obtained and stored in the seventh image memory 76, and then the calculation condition stored in the seventh image memory 76 and the smoothing condition stored in the sixth image memory 72. The coordinate series indicating the transformed outer shape and a set for each character type are output to the standard pattern memory 42 shown in FIG.

In this way, a pair of standard character patterns and their calculation conditions are registered in the standard pattern memory 42 for each character. For example, for the character type “5”, FIG.
f and h are registered as standard character patterns and calculation conditions.

Character Recognition Unit The character recognition unit 300 of this embodiment includes an outer shape extraction circuit 40, a standard pattern memory 42, a distance difference calculation circuit 44, and a character type determination circuit 46, and as shown in FIG. It is formed to recognize an unknown character pattern by side-setting.

Then, as in the case of creating a standard character pattern, the engraved character A stamped on the frame 12 is photographed using the TV camera 16 and detected / cut out for each character using the character detection unit 100. After the size and position are normalized, the unknown character image pattern is sequentially input to the outer shape extracting circuit 40.

The outer shape extracting circuit 40 creates a circumscribed rectangular frame of an unknown character image pattern, scans the contour line of the character pattern from the left side and the right side of the circumscribed rectangular frame, and determines the value of the distance from each side to the contour line of each side. A coordinate series is created corresponding to the position, and each is obtained as an outer shape for the left side and an outer shape for the right side.

Further, with respect to the contour shapes for the left side and the right side, similarly to the contour shape smoothing circuit 70 of FIG. 3, a coordinate series in which the contour shape is smoothed is obtained, and this is directed to the distance difference calculation circuit 44 as an unknown character pattern. Output.

FIG. 6 shows a state in which the contour shape extraction circuit 40 and the distance difference calculation circuit 44 of this embodiment extract the contour shape for the character type "5" and calculate the distance to the standard character pattern "3". ing.

For example, FIG. 6A shows a state in which a circumscribing rectangular frame b is created for a normalized pattern a of the character type “5”, and an outer shape c for the left side and an outer shape d for the right side are obtained. Further, FIG. 6 (b) shows a state in which the outer shape c with respect to the left side is smoothed to obtain the outer shape e.

FIG. 5 shows a specific configuration of the distance difference calculation circuit 44 of this embodiment. The smoothed contour shape of the unknown character pattern sent from the contour shape extraction circuit 40 is a shift pattern. It is input to the creating circuit 44a.

Then, the shift pattern creation circuit 44a shifts the position of the input contour shape by one pixel to the top, bottom, left, and right.
A new contour shape is newly created, and for the same character type, five types of contour shapes are created for each of the top, bottom, left, and right together with the reference contour shape.

On the other hand, from the standard pattern memory 42, the left and right smoothed contour shapes indicating the standard pattern of each character type are sequentially sent and stored in the standard character pattern setting memory 42a, and the calculation conditions thereof are the calculation condition setting memory. It is stored in 42b.

Then, the outer contour shape difference circuit 44b first selects one of the five outer contour shapes that are shifted by the shift pattern creating circuit 44a and stores the outer contour shape in the standard character pattern setting memory 42a. The coordinate shape corresponding to the difference between the two is created, and the coordinate series is created and then output to the weighted average calculation circuit 44c.

For example, in FIG. 6B, the left outer shape e of the character type “5” and the left outer shape f of the character type “3” of the standard character pattern are overlapped with each other, and the coordinate series h indicating the difference shape thereof is shown. Is shown to be created.

Then, the weighted average calculation circuit 44c uses the inter-outer shape difference circuit 4
For the coordinate series showing the difference shape sent from 4b,
According to the calculation condition sent from the calculation condition setting memory 42b, while adding a predetermined load to the range indicating the characteristic part of the standard character pattern, the values of the coordinate series are summed over all coordinate series, and the value is calculated by the number of coordinate series. An averaged value is obtained, and the averaged value is output to the minimum distance selection circuit 44d as a distance difference α.

In FIG. 6B, the difference shape h for the character type “5” is shown.
The distance is calculated by adding a load to the characteristic range g
An example is shown in which a value i is obtained as the distance difference α.

In this manner, the same calculation is performed for all of the five types of position-shifted outline shapes created by the shift pattern creation circuit 44a to obtain the distance difference α, which is output to the minimum distance selection circuit 44d.

The minimum distance selection circuit 44d selects the minimum value among the five types of distance differences α sent from the weighted average calculation circuit 44c and outputs it to the character type determination circuit 46 of FIG. That is, the minimum value of the distance α is selected and output for each of the left and right contour shapes.

Then, as shown in FIG. 2, the character type determination circuit 46 stores the distance differences α for the left and right outline shapes sent from the distance difference calculation circuit 44, respectively, and stores the distance differences α for all standard character patterns. After that, the distance differences α are rearranged for the left outer shape and the right outer shape.

That is, the sum of the distance differences α for the left and right outline shapes of a certain standard character pattern is rearranged in ascending order,
When the character type with the smallest sum is the first candidate and the character type with the second smallest sum is the second candidate, the value of the first candidate is smaller than a predetermined value and the value of the difference between the first candidate and the second candidate. The character type of the unknown character pattern is determined to be the first candidate character type only when the condition that is larger than a predetermined value is satisfied, and in other cases, it is determined that there is a reading error and cannot be determined.

At this time, if necessary, only the coordinate series of the range representing the characteristic part of the calculation condition is used, and the difference β of only the specific range is calculated in the same manner as the difference α.

The difference β thus obtained is larger than the difference α when the unknown character pattern and the standard character pattern do not match. In particular, in the case of similar character types, the difference β obtained by paying attention only to the characteristic part is larger than the difference α and is easy to identify in order to identify the similar character type.

Therefore, the character type determination circuit 46 can determine the character type with higher accuracy by using only the difference α or the difference α or β.

In this way, according to the present invention, the engraved character can be read quickly and accurately.

Note that once the standard character pattern is stored in the standard pattern memory, character recognition can be performed using the standard pattern memory. Therefore, the line switching circuit 34 and the standard character pattern automatic generation circuit 200 are optional, It can be shared by the character recognition device.

Further, in the above-described embodiment, the case where the rectangular frame is used as the circumscribing frame of the character has been described as an example, but the present invention is not limited to this, and a circumscribing frame having another shape may be used as necessary. .

Further, in the above-described embodiment, the case of recognizing a stamped character has been described as an example, but the present invention is not limited to this and may be used for recognizing another character as necessary.

Further, in the above embodiment, the case where the optical image pickup means is used has been described as an example, but the present invention is not limited to this,
Other types of imaging means may be used if desired.

[Brief description of drawings]

1 is a block diagram of a standard character pattern creating apparatus according to the present invention, FIG. 2 is a block diagram of a preferred embodiment of a character recognition apparatus to which the present invention is applied, and FIG. 3 is an apparatus shown in FIG. FIG. 5 is a detailed block diagram of a standard character pattern automatic creation circuit used in FIG. 4, and FIG. 4 is an explanatory view showing a state of creating a standard character pattern for a character type “5” in the standard character pattern automatic creation circuit shown in FIG. The figure is a detailed block diagram of the distance difference calculation circuit in the apparatus shown in FIG. 2, and FIG. 6 is the character type "5" in the outer shape extraction circuit and the distance difference calculation circuit of the embodiment apparatus shown in FIGS. It is explanatory drawing which shows the state which extracts a contour shape and calculates the distance with the standard character pattern "3". 10 …… Character recognition device 16 …… TV camera as image capturing means 22 …… Binarization circuit 40 …… Outline shape extraction circuit 42 …… Standard pattern memory 62 …… Similar character type selection circuit 66 …… Outside feature extraction circuit 70 …… Outer shape smoothing circuit 72 …… Memory memory 74 …… Distance calculation condition determination circuit 78 …… Standard pattern creation circuit 100 …… Character detection unit 200 …… Standard character pattern creation device 300 …… Character identification unit A… … Engraved characters

Claims (5)

[Claims] 1. A character pattern detecting means for obtaining a plurality of binary image character patterns under different conditions for each character type, and a plurality of binary image character patterns obtained for the same character type are accumulated. A cumulative pattern creating means for creating a cumulative pattern representing a frequency distribution of whether each pixel of the character pattern is a character part or a background part; and a plurality of parts for extracting a high frequency part of a character part from the cumulative pattern. An average character pattern creating means for creating an average pattern of the character pattern, and a frame circumscribing the average character pattern is created, and a distance coordinate series from each side of the circumscribing frame to the outline of the character Using a contour shape creating unit that obtains the contour shape of the character and a distance coordinate series of each side obtained from the contour shape creating unit A similar character type selection means for selecting a character type, an outer shape feature extraction means for comparing the outer shape of the focused character type and the similar character type, and extracting a coordinate section having a large difference between them as a characteristic part, and the outer shape creation The contour sequence smoothing means for smoothing the coordinate series representing the contour shape of each side obtained by the means, and creating the coordinate series of the smooth contour shape as a standard character pattern, and the contour feature part extracting means A storage memory that stores, for each character type, a range that indicates a characteristic portion of the outer shape and a coordinate series that indicates the standard character pattern obtained by the outer shape smoothing unit, and is stored in the storage memory. Using the coordinate series showing the smoothed outer shape and the range representing the characteristic part of the coordinate series, the character part of interest and the other character types are pattern-matched to represent the characteristic part. Comparing while adding an appropriate load to the coordinate series in the circle, summing the differences between the coordinate series over all coordinate series, weighting the total value by the number of coordinate series to obtain the distance difference, and the distance difference is the maximum. Distance calculation condition determining means for determining the value of the load so that the value of the load given to the range indicating the characteristic portion obtained by the distance calculation condition determining means and the characteristic portion stored in the storage memory are shown. A standard character pattern comprising a range as a calculation condition, and a standard pattern creating means for outputting a combination of the calculation condition and the standard character pattern stored in the storage memory for each character type. Creation device. 2. The apparatus according to claim 1, wherein the outline shape creating means creates a rectangular frame circumscribing the average character pattern, and a distance from both left and right sides of the circumscribing rectangular frame to the character contour. A standard character pattern creating device, characterized in that a pair of left and right coordinate series representing the above is obtained as an outer shape of a character having each side. 3. The apparatus according to any one of claims (1) and (2), wherein the character pattern detection means is an image pickup means for reading a character, and a character detection for cutting out a character pattern from the read image data. And a character detecting section for cutting out a pattern of each character from the binary image data with a predetermined circumscribing frame, the character detecting section converting the read image data into binary image data and outputting the binary image data. A standard character pattern creating device comprising: a means and a normalizing means for normalizing and outputting the position and size of the cut out character pattern. 4. The apparatus according to claim 3, wherein the character detection unit performs expansion / contraction processing on the binary image data to remove isolated pixel data that causes noise, and character detection cutout means. A standard character pattern creating apparatus having an expansion / contraction circuit for outputting to a user. 5. A standard character pattern creating device according to any one of claims (1) to (4), characterized in that a standard character pattern of an engraved character and its calculation condition are created.