JPH10222607A - Method for recognizing separation of graphic element from character element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely recognized separation even when a graphic element is brought into contact with a character element. SOLUTION: A number circle is processed in S1, a processing for adopting θ=0 deg. is decided in S2, then, and whether θis smaller than 180 deg. or not is judged in S3. At the time of Y in judgment, two contact lines in the angle θ of a contour element group are calculated by S4. It is judged whether or not the widths of the two calculated contact lines are out of the standard of the number circule in S5. When they are within a standard, contour elements are judged to be within distance (d) from the two contact lines in S6. At the time of Y by the judgment, a mark is given to the contour element in S7 and the processings from S3-S7 are repeated till θ becomes 180 deg.. At the time of θ>180 deg., it is judged whether or not a part with the mark exists in the contour element or not in S8 so as to adopt a contour element group as a circle element in S9 when it is given and to recognize a circle in S10. When it is judged that the mark does not exist, the contour element group is adopted as a character element in S11 and character recognition is executed in S12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic drawing input device for optically reading and recognizing a drawing containing characters and figures, and separates a graphic element such as a circle from a character element such as a number drawn in the circle. The present invention relates to a method for separating and recognizing graphic elements and character elements.

[0002]

2. Description of the Related Art When a computer reads characters written in a document or a drawing, the subject is first raster-scanned by an image pickup means such as an image scanner, and the binary pattern data corresponding to the black and white of the input pattern is used as a target. The recognition process is performed by extracting data of a character and referring to the dictionary. When the subject is a drawing or a table in which characters, symbols, figures, and the like are mixed, it is necessary to first separate the character portion from the graphic portion, and then cut out the information for each character to perform recognition. Characters included in drawings are often not uniform in character size, and are therefore very difficult to extract and recognize. Therefore, before cutting out the characters, the input image is converted into a contour vector, and the elements are separated. First, character candidates are determined based on the size of the circumscribed rectangle of the isolated contour vector loop. As shown in FIG. 5, the conditions of the character candidates are as follows: When the width of the vector is L ₁ , the height is L _2, and the threshold value defining the maximum value of the character is L ₀ , L ₁ , L ₂ ｝ <L ₀ . FIG. 6 shows that a character candidate having the same height as the character string to be searched is used as a core of the character string candidate.
A character candidate having center coordinates in a range as shown in FIG. The procedure is as follows:
The center point of another character candidate is searched in the range as shown in (b), and the detected one located farthest from the central nucleus is set as the start point of the next search range, and is not detected. In this case, the search on the right side ends, and a similar search is performed toward the left side. From the character string candidates detected by these searches, as shown in FIG. 6C, i, the height hc of the nucleus and the distance d between the candidates are: d (i, j) <hc × constant (1 / When 2 ≦ constant ≦ 1), i and j in the character string candidate of the character are extracted as a character string.

[0003]

In the conventional character recognition device, there are the following restrictions in order to correctly separate characters. That is, (1) the outer periphery of a contour vector constituting a character can be distinguished from the outer periphery of a contour vector other than a character. Usually, if the outer circumference of the contour vector is larger than a predetermined value, it is determined that the outline vector is a figure other than a character, and those within the predetermined value are determined as a character outline vector. (2) The outline vector of a character is not in contact with a figure other than other characters, for example, a line or a symbol. However, when a character is written in a frame using a character string with a frame such as a table, the character comes into contact with the outline vectorized character, such as the numbers “1”, “4”, and “6” shown in FIG. In many cases, the performance of character recognition for such applications is reduced.

[0004] In addition to the above, when a graphic element composed of a circle and a character element composed of a number are mixed, a circle is first detected, and then a first character (number) inside the circle is recognized. Alternatively, a second method of registering, for example, a three-digit number in a dictionary and performing symbol recognition or character recognition is used.

However, in the first method, when a graphic element composed of a circle is in contact with a character element or when a graphic element composed of a circle is distorted, the graphic element composed of a circle and the character element are separated. In addition to the problem that it becomes difficult, there is also a problem that even when a graphic element composed of a circle is missing due to blurring, it cannot be recognized as a graphic element composed of a circle. Further, in the second method, since it is necessary to register all patterns, there is a large problem in terms of memory and time.

The present invention has been made in view of the above circumstances, and it is possible to reliably perform separation recognition even when a graphic element and a character element are in contact with each other. An object of the present invention is to provide a method for separating and recognizing graphic elements and character elements that can reliably perform separation recognition.

[0007]

According to the present invention, in order to achieve the above object, after determining a continuous contour element, a parallel tangent is calculated as the contour element so as to sandwich the contour element. Identifiers are added to contour elements that exist within a certain distance from the tangent line, and the parts with and without identifiers are detected, and the contour elements of the attached parts are recognized as figures as graphic elements. Then, the outline element of the portion not to be added is recognized as a character element as a character.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart for describing an embodiment of the present invention. In FIG. 1, step S1 is a process of determining a continuous contour element as one group. This step S1 is performed, for example, as shown in FIG. ,
It processes a figure consisting of a number circle in which the number "2" is drawn in a circle. In FIG. 2, the outline element groups {A, B, C, D, E} are divided by A, B, C. Next, in obtaining a tangent, if the tangent is vertical as shown in FIG. 3, a process of setting θ = 0 ° is determined in step S2, and whether or not θ is smaller than 180 ° is determined in a process of step S3. If the result of determination is “Y”, two tangents at the angle θ of the contour element group are calculated in step S4 as shown in FIG. The two tangent lines are formed in parallel so as to sandwich the number circle.

In step S5, it is determined whether the calculated widths of the two tangents are out of the standard of the number circle. If the result of the determination is "Y" which is out of the standard, the outline element group ｛, 、, 、, 、, 、, 、
It is assumed that｝ is noise, and if “N” in the standard, it is determined whether or not the contour element is within a distance d from two tangents in step S6.
Is determined. As a result of the determination in step S6, if "N", it is processed as noise, and if "Y", in step S7, marks (identifiers) are added to the contour elements PIA and II as shown in FIG. Increase (θ = θ + Δθ), and θ becomes 1
Steps S3 to S7 are repeated until the angle reaches 80 °. FIG. 4 shows a case where θ is 90 °,
The outline element {@} is also marked.

When it is determined in step S3 that θ has become θ> 180 °, that is, when it becomes “N” in step S3, the process of step S8 is performed. In the process of step S8, it is determined whether or not there is a marked portion in the contour element. If the contour element is "Y", the contour element group is set as a circle element in step S9, and step S1 is performed.
Recognize a circle as 0. If it is determined in step S8 that there is no mark and "N", the outline element group is set as a character element in step S11, and character recognition is performed in step S12. The circle elements and the character elements recognized in steps S10 and S12 are grouped in step S13.

In a drawing composed of a graphic element such as a number circle and a character element as described above, the tangent line always contacts the graphic element portion and the tangent line does not contact the character element. A graphic element and a character element can be separated using a tangent line as shown in FIG.

[0012]

As described above, according to the present invention,
Even if a character element is in contact with the graphic element part, both elements can be reliably separated, and even if the graphic element part is faint, both elements can be similarly separated. Further, both elements can be separated in a short time without using much memory. In addition, there is an advantage that even if the graphic element part or the character element part fails in the recognition stage, it can be easily corrected in subsequent processing.

[Brief description of the drawings]

FIG. 1 is a flowchart describing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a number circle.

FIG. 3 is an explanatory diagram when a tangent line is attached to a number circle.

FIG. 4 is an explanatory diagram when a tangent becomes 90 °.

FIG. 5 is an explanatory diagram of a character recognition process.

FIG. 6 is an explanatory diagram of a character recognition process.

FIG. 7 is an explanatory diagram of a contour vector.

Claims (1)

[Claims] After determining a continuous contour element, a parallel tangent is calculated as a contour element so as to sandwich the contour element, and an identification object is assigned to a contour element existing within a predetermined distance from the tangent. After the identification, the part with the identification body and the part without the identification are detected, the outline element of the part with the identification is recognized as a graphic element as a graphic element, and the outline element of the part without the identification is recognized as a character as a character element. A method of separating and recognizing graphic elements and character elements.