JP2501832B2 - Extraction method of color mark area - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for automatically extracting a region marked with a color pen from a document image by using a digital image processing method.

[Conventional technology]

Regarding the extraction of the information marked with a color pen in the document image, as described in JP-A-60-31682,
The coordinates of the four points in the marked area were extracted by taking the peripheral distribution in the vertical direction. That is, 1 in FIG. 5 (a) is a color mark marked with a color pen, and the peripheral distribution in the horizontal direction of this color mark 1 is 2 and the peripheral distribution in the vertical direction is 3 as well. From now on, the coordinates X ₁ , X ₂ and Y ₁ , Y ₂ 4
The point is decided.

[Problems to be solved by the invention]

As described above, since the color mark 1 is extracted as a rectangle circumscribing the area surrounded by the color pen, FIG.
When the color mark 1 has a shape as shown in,
As in the case of FIG. 7A, four points of X ₁ , X ₂ , Y ₁ , Y ₂ are determined from the horizontal peripheral distribution 2 and the vertical peripheral distribution 3, so that even extra information is extracted. There was a flaw. Further, as a conventional area extracting method of this kind, there is a method of tracing the color mark 1 by line and extracting information in a closed loop. In this method, since points on the color mark 1 are sequentially traced, it is possible to extract a region faithful to an arbitrary mark shape without depending on the shape of the color mark 1, but the line tracing process is performed in eight directions of the pixel of interest. Generally, it takes a lot of time to process because the connectivity of is checked, and there is a drawback that the load on the CPU is too large to execute on an OA device such as an electronic file system.

An object of the present invention is to solve the above-mentioned conventional drawbacks, and to speed up the area marked with a color pen,
In addition, the present invention provides a method for extracting a color mark area for accurate extraction.

[Means for solving problems]

A method of extracting a color mark area according to the present invention, means for extracting a color mark drawn with a color pen on a document, and a peripheral distribution of a color image in the horizontal and vertical directions of the document with respect to the extracted color information, A means for obtaining the apex of a rectangle circumscribing the color mark area, a means for confirming the existence of a color mark in the vicinity of each apex of this rectangle, and a horizontal point with the apex of the rectangle as a reference point when the apex of the rectangle does not exist on the color mark, The presence of a color mark is searched in the vertical direction toward other vertices, the color mark is detected in each direction, and a rectangular reference point formed by the coordinate points of the two detected color marks and the reference point is detected. A means for calculating the fourth vertex facing each other is provided, and the above-described color mark search processing and existence determination processing are repeated until it is confirmed that all the extracted vertices are present on the color mark. One in which the.

[Action]

In the present invention, the extraction of the coordinates of the vertices of the prolongation circumscribing the color mark in the document image is used as a starting point, and it is determined whether or not each vertex of the prolongation is present on the color mark. If not, the two processes of searching for the color marks toward both adjacent vertices are repeated until it is confirmed that all the vertices are on the color mark, and the process is surrounded by a color pen. The boundary of the enclosed area is approximated by horizontal and vertical line segments, and the enclosed area is extracted.

〔Example〕

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

FIG. 1 is a block diagram showing the structure of an apparatus for carrying out the present invention. In this figure, 11 is a document image of an original image marked with a color pen, 12 is an image input that optically scans the document image 11 and performs photoelectric conversion, and quantizes the obtained electric signal according to the signal strength. Reference numeral 13 denotes a color mark separation unit, which separates into three types of information in the original image, the paper surface, characters, and color marks. 14 is an area extraction unit for extracting the coordinates of the four vertices of the circumscribed rectangle of the color mark area or the character string by taking the peripheral distribution of the pixels in the horizontal (X) direction and the vertical (Y) direction, and 15 is the area of each rectangle. A color mark determination unit that determines whether or not each vertex is on a color mark, 16 is a color mark search unit that searches for a color mark toward both adjacent vertices when the vertex is not on the color mark, Reference numeral 17 is a memory of the computer, 18 is a central processing unit (CPU) of the computer, 19 is a display, 20 is a common bus of the computer, and 21 is an information storage unit, which are connected as shown.

FIG. 2 shows the flow of actual processing performed in this embodiment. Following the flow of this processing, the operation is as follows.
Note that (1) to (11) in FIG. 2 indicate each step.

In order to explain the operation of each unit in FIG. 1, it is assumed that an article in a newspaper is electronically clipped. First, enclose the desired article in the newspaper with a mark with a colored pen, and use this as the document image 11 in the image input section.
It is input by an image input device such as an image reader or a camera shown in 12 (1). The image input unit 12 optically scans the original image, performs photoelectric conversion, and quantizes the obtained electric signal according to the signal strength. Next, the quantized signal is subjected to color mark extraction in the color mark separation unit 13 by using the following method described in, for example, the above-mentioned JP-A-60-31682.

Assuming that the signal strengths of the paper surface, characters and color marks in the newspaper are read by a monochrome image reader, as shown in FIG.
h), character 5 (low), color mark 1 (intermediate) and 3
Separated into two levels. Then, the paper surface 4 and the color mark 1 are _separated by the threshold value THD _hiah , the character 5 and the color mark 1 are separated by THD _low , and two are extracted (2). Next, the color mark 1 is extracted by taking the exclusive OR of the respective outputs (3). The binarized character information and color mark information obtained by the color mark separation unit 13 are temporarily stored in the memory 17 of the computer separately. Next, in order to obtain the position coordinates of the extracted color mark 1, when the peripheral distribution of pixels relating to the color mark information is taken in the direction perpendicular to the paper surface in the area extraction unit 14, FIGS. 5 (a) and 5 (b) are obtained. The vertical peripheral distribution 3 of the color pixels as shown in (3) is obtained, and by cutting this with an appropriate threshold value, the position coordinates of the vertical area start point (Y1) and end point (Y2) of the color mark portion are obtained ( 4). Next, the distribution range Y1, Y2 of the mark area obtained by the peripheral distribution in the vertical direction
If the peripheral distribution of the color information is taken in the horizontal direction in the width indicated by, the position coordinates of the area start point (X1) and end point (X2) of the color mark in the horizontal direction are similarly obtained (5). X1, X2, Y1, Y2 obtained by the area extracting unit 14 are four vertices A1 (X1, Y1), A2 (X2, Y1), A3 (X1, Y2), A4 of the rectangle circumscribing the color mark 1.
It means the coordinates of (X2, Y2) (6). By the way, for example, with respect to the shape of the color mark 1 shown in FIG. 5 (b), the area surrounded by the vertices A1 to A4 obtained by the area extracting unit 14 extracts the color mark area with sufficient accuracy. Is hard to say. Therefore, the color mark determination unit 15 determines whether or not the vertices A1 to A4 of the circumscribing rectangle are present on the color mark (7). The vertex search process will be described below with reference to FIG.

Since the vertices A1, A2, A4 are present on the color mark 1, the position coordinates are stored in the memory 17 of the computer as vertices in this case. On the other hand, when a vertex like the vertex A3 does not exist in the color mark 1, the color mark search unit 16 sets X1 = constant and Y2 = constant toward the two adjacent vertices A1 and A4 with the vertex as a reference point. The color mark 1 is searched (8). When the color mark 1 is detected, the point is A5
(X1, Y3), A6 (X3, Y2). Since A5 and A6 are part of the vertices of the area surrounded by the color mark 1, the position coordinates of these two points are stored in the memory 17 of the computer. Next, vertices A3, A5, A6
Find the other vertex A7 of the rectangle containing. The position coordinate of the vertex A7 is (X3, Y3). Then, the processing is transferred to the color mark determination unit 15 again, and it is determined whether or not the vertex A7 is present on the color mark 1. If the vertex A7 is present on the color mark 1, the position coordinate of A7 is stored in the memory 17 of the computer. The process ends. In this case, the area of the color mark 1 is extracted as obtained by connecting A1, A2, A4, A5, A6 and A7. If it does not exist on the color mark 1 as shown in FIG. 4, Y3 = constant and X3 = constant are searched for with A7 as a new reference point toward the vertices A5 and A6 adjacent to A7. When the color mark 1 is detected, these points are stored as vertices in the memory 17 of the computer as A8 (X3, Y4) and A9 (X4, Y3), respectively. And again
Another vertex A10 (X4, Y4) of the rectangle containing A7, A8, A9
Is calculated. Then, it is determined whether or not the vertex A10 exists on the color mark 1, and if it exists on the color mark 1, the vertex A10 is stored in the memory 17 of the computer as the vertex. If it does not exist on the color mark 1, the search for the color mark 1 and the search for the color mark 1 are performed until it is confirmed that the obtained vertex An (n ≧ 1,2,3, ...) Exists on the color mark 1. The judgment is repeated. In this way, a set of vertices An that enclose the outer shape of the color mark 1 with the group of horizontal and vertical line segments is obtained.

Next, the set of the vertices An of the color mark 1 is mapped to the character information obtained as a result of binarization with the threshold THD _low in the binarization process of step (2), and the vertex An
The area inside the line segment connecting the lines is extracted, the extraction result is stored in the memory 17 of the computer, and the cutting operation is completed. This completes the extraction of the character information surrounded by the color mark 1 in the original document.

As described above, conventionally, the character information surrounded by the color mark 1 in the document is cut out by a rectangle circumscribing the enclosing shape of the color mark 1. Therefore, when the color mark shape is not rectangular, it is unnecessary in the original document. Even information was cut out, but by using the present invention, it is possible to cut out with a group of horizontal and vertical line segments as faithfully as possible to the shape with the color mark 1. Further, the present invention can be applied to a case where an article in a printed document such as a newspaper is marked with a color pen to mark an area, and information in the marked area is automatically extracted. Even if it is not drawn straight using a ruler, the article layout can be separated by a combination of horizontal and vertical line segments, and the shape of the article is the circumscribed rectangle of the mark area obtained by processing the peripheral distribution. Is a rectangle in which a maximum of two vertices of the four vertices can be concave with the basic pattern as a basic pattern. Therefore, in the color mark search process, horizontal (Y = constant) and vertical (X = constant).
Since it is only necessary to limit the processing to one direction)
There is an advantage that the processing time can be significantly shortened as compared with the area extraction using the conventional line tracing method.

Further, since it is determined whether or not the extracted vertex exists on the color mark 1 and the search for the color mark 1 is executed only when it does not exist, the processing already known from Japanese Patent Laid-Open No. 60-31682. Connecting the process of the present invention to the process has an advantage that the consistency of the processing process is good such that the process can be inherited without changing the data format.

In the above embodiment, the area marked with a color pen is input by a monochrome image reader, and the color mark 1 is extracted by taking the exclusive OR of the result of binarization with two threshold values to represent the area. An example of executing the vertex coordinate extraction process has been described, but it is also possible to input a document with a color scanner and execute the same color mark determination and search processing on the extracted color region.

〔The invention's effect〕

According to the present invention, a means for extracting a color mark drawn with a color pen on a document, and a peripheral distribution of a color image in the horizontal and vertical directions of the document with respect to the extracted color information, and a rectangular shape circumscribing the color mark area are taken. A means for obtaining vertices, a method for confirming the existence of a color mark near each vertex of this rectangle, and a method in which the vertices of a rectangle do not exist on a color mark, and the vertices are used as reference points to move horizontally or vertically toward other vertices. The presence of the color mark is searched for, the color mark is detected in each direction, and the fourth vertex that faces the reference point of the rectangle formed by the coordinate points of the detected two color marks and the reference point is calculated. The above-described color mark search processing and existence determination processing are repeated until it is confirmed that all the extracted vertices are present on the color mark. The process logical operation of a binary, easily hardware the process because it consists of a determination process by the count and threshold pixels seeking, there is an advantage that high-speed processing.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of an apparatus according to the present invention, FIG. 2 is a flow chart of a mark area extracting procedure according to the present invention, and FIG. 3 is a diagram when a monochrome image reader is used. FIG. 4 is an explanatory diagram of an example of output signal strength of a color mark by a document sheet, characters, and color pens, FIG. 4 is a schematic diagram of a color mark determination and color mark search procedure, and FIGS. 5 (a) and 5 (b) are conventional peripherals. It is an explanatory view showing an example of area extraction using a distribution method. In the figure, 11 is a document image, 12 is an image input unit, 13 is a color mark separation unit, 14 is a region extraction unit, 15 is a color mark determination unit, 16 is a color mark search unit, 17 is a memory, 18 is a CPU, 19 Is a display, 20 is a common bus, and 21 is an information storage unit.

Claims (1)

(57) [Claims] 1. A method for extracting an area of a document surrounded by a color pen in a document image, wherein the means for extracting a color mark drawn by the color pen on the document, and the extracted color information, A means for obtaining the peripheral vertices of the color image in the horizontal and vertical directions of the document and obtaining the vertices of a rectangle circumscribing the color mark area, a means for confirming the existence of the color marks near each vertex of the rectangle, and a vertex of the rectangle. Is not on the color mark, the vertex is used as a reference point to search for the existence of the color mark toward other vertices in the horizontal and vertical directions, the color mark is detected in each direction, and the detected two colors are detected. A means for calculating a fourth vertex facing a rectangular reference point constituted by the coordinate point of the mark and the reference point, and until it is confirmed that all the extracted vertices are present on the color mark, Method of extracting the color mark region and repeating the presence determination process and the search process of the serial color mark.