JPH05143733A - Contour extracting device - Google Patents

Abstract

(57) [Abstract] [Purpose] All the areas inside the contour are filled by hardware and the area enclosed by the contour inside by the operation of exclusive OR is extracted. The purpose is to extract the contour. A pixel group in which a closed region of the image data of interest, which is surrounded by the extracted contour, is filled, among the means for extracting the contour of the quantized image data,
Means for taking exclusive OR with the closed area of interest, and contour extraction of closed area existing inside the outline of the closed area of interest extracted by taking exclusive OR It is characterized in that it is configured by means for sequentially performing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus and a display apparatus, which are one of computer peripherals, and more particularly to an apparatus for extracting contours of a binarized image representing characters and images.

[0002]

2. Description of the Related Art Conventionally, a sequential detection method has been used to detect the inner contour of a binarized image. This has the following three procedures.

(1) A procedure of determining either the vertical or horizontal direction as the scanning direction, sequentially inspecting 1/0 of pixels in the scanning direction, and obtaining a white area.

(2) A procedure for starting a white area in the obtained white area and searching the white area in the upward, downward, right, and left directions.

(3) A procedure for registering that both white regions are the same when the white region currently being searched includes a part of the already obtained white region and a point having the same coordinates.

If the white area is detected by sequentially performing the above three steps, the inner contour included in the closed black area can be detected. For example, the pixel group forming the character “B” has two white areas inside. By repeating the above three procedures, it is possible to detect two white areas independent of each other. FIG. 17 shows an explanatory diagram of this example.
The first white area is detected by scanning in the direction of arrow 40, and the white areas detected by arrows 41 and 42 are determined to be the same as the first white area. On the other hand, the second white area is detected by scanning in the direction of arrow 43.

On the other hand, if the same means is used for the pixel group forming the character "C", it is detected that the white region includes the coordinates of the start of scanning, so that the outline inside the closed black region exists. You can decide not to.

[0008]

As is apparent from the above example, in the conventional method, it is necessary to perform the scanning the same number of times in the number of pixels in the vertical direction as indicated by arrows 40 to 43 and the like. It was In this case, there is a problem that a lot of processing time is required.

The present invention has been invented in order to solve the above-mentioned problems of the prior art, and it is surrounded by the outline existing inside by the filling of the area within the outline by the hardware and the exclusive OR operation. It is an object to extract all contours at high speed and easily by a means that also combines the extraction of the extracted regions.

[0010]

SUMMARY OF THE INVENTION The present invention is a device for extracting the outline of quantized image data, which comprises a pixel group in which a closed region of the extracted outline is filled and a closed region of interest. It is composed of a means for taking an exclusive OR, and a means for sequentially extracting the contour of a closed region which is extracted by taking the exclusive OR and exists inside the contour of the closed region of interest and which is not filled. It is characterized by

[0011]

According to the above apparatus of the present invention, in extracting the contour of a binarized image, particularly when extracting the inner contour, a closed area surrounded by the contour extracted immediately before is filled by hardware to obtain By taking the exclusive OR of the selected pixel group and the original pixel group, it is possible to extract a white area that is not originally filled. Further, the same processing is performed for this area, and the inner contour is also extracted. All contours are extracted by repeating the above method.

[0012]

EXAMPLES The present invention will be described in detail below based on examples. FIG. 1 is a configuration diagram of contour extraction of the present invention. In the figure, reference numeral 51 denotes an original image memory, and the original data stores general binary image data representing characters and images. Reference numeral 52 is a contour extraction unit that executes a contour extraction unit described later in FIG. The outermost contour of the original image data is extracted by this processing, and then, based on this pixel data, the filling section 53 performs filling by a known method according to the odd-even rule. The pixel data obtained as a result is stored in the primary working memory 54, and the pixel data of the original image is stored as it is in the secondary working memory 55.
To store. Here, the pixels in the black area to be filled are set to 1 and the pixels in the white area to be not filled are set to 0. The band reading units 56a and 56b read the pixel data from the respective working memories 54 and 55, and the exclusive OR circuit 57 takes the exclusive OR of both data. From this, the first closed region included inside the contour extracted by the contour extraction unit 52 can be detected. The band writing unit 58 writes the detected pixel data in the image memory 59. These series of steps are repeated up to the required number of pixels for the resolution of the output device. In addition, the exclusive OR circuit 5 is provided over the entire range of the image.
If there is no non-zero pixel as a result of extracting the pixel group by 7, it is clear that all contours have been extracted, and this process ends. A program for performing the above processing is written in the ROM 61, and is controlled by the microprocessor unit (MPU) via the address bus 62 and the data bus 63.

FIG. 2 is a flowchart showing the basic structure of contour extraction according to the present invention. As the original data, general binary image data representing characters and images is used. In this device, original data formed by dots, which is recorded in a semiconductor ROM or the like, is read at (1) in the figure.
Next, the pixel of interest is extracted by sequentially examining the inside of the detection area. The data of the original pixel group formed by the dots is D0 (2). Contour extraction is executed using the extracted pixel as a starting point (3).

The contour extraction is performed by ANIL K. Method reported by JAIN (ANILK.JAIN "FUNDAM
ENTALS OF DIGITAL IMAGE P
LOCSING "Prentice-Hall
1989). It is known, but briefly described. J
In the AIN method, the coordinates of the contour portion of the binarized image are determined as shown in the flowchart of FIG. Here, it is assumed that the pixel to be displayed has the value “1” and the pixel that is not displayed has the value “0”. First, the pixel of interest is taken out (10). When the pixel is taken out, if the detection area has already made one round, the processing ends (11). In other cases, it is judged whether the value of the pixel of interest is 1 (12), and if it is 1, the traveling direction is determined to the left and the process proceeds by one step (13). If the result of the judgment (12) is not 1, the direction of travel is determined clockwise and the process proceeds one step (1
4). After that, the process returns to the process (10) and the same process is repeated.
The state of this processing is shown in FIG. First, in the boundary 15 of the detection area, the pixel groups indicated by the point group 16 are sequentially examined,
Find the first non-zero pixel. This is a pixel included in the non-zero pixel group 18. After that, when the method of FIG. 3 (flow chart) is used, the pixel group located in the contour portion is detected along the locus shown by the polygonal line 17. If the position coordinates are continuously recorded each time the process (13) is performed, an array of position coordinates of pixels in the contour portion can be obtained. If the distance difference is calculated between the adjacent elements of this position coordinate array, the difference between the horizontal and vertical methods is {{up, down,
An array of vectors consisting of four directions of right and left can be created. If you trace the array of this vector, you can see the polygonal line 1 in FIG.
The contour line can be taken out as shown in 9.

The closed area surrounded by the contours extracted by the above-mentioned means is filled (4). The data of the pixel group of dots at this time is set as D1. As the filling method, a method according to the well-known odd-even rule was adopted. In this embodiment, the filling is performed by hardware.

Next, the exclusive OR of the data D1 and the original data D0 extracted by the above means is calculated (5). The data obtained here will be referred to as D0 again for the following description. That is, if there is a contour included in the closed area of the already extracted contour, it is possible to extract the closed area surrounded by the inner contour by taking the exclusive OR. Therefore, it is checked again whether there is a pixel of interest (6), and if it does not exist, the process ends. However, if it exists, the contour extraction of the pixel group generated above is performed (3). By performing this operation until there are no more pixels of interest, all contours can be extracted.

Further, the processing in FIG. 2 will be described in detail later.

In FIG. 6, the first non-zero pixel is determined. First, it is present in the boundary 25 of the detection area and should be extracted from now on.
The pixel group 27 which is the original data is sequentially examined in FIG. After that, by further performing the processing shown in FIG. 3, the pixel group located in the contour portion along the locus 26 of the detection processing is detected. The contour line 28 in FIG. 8 can be extracted by obtaining the array of position coordinates of pixels in the contour portion.

Next, using the filling hardware of the method according to the odd-even rule, the closed area surrounded by the contour line 28 in FIG. 8 is filled. This pixel group is shown at 29 in FIG. If the exclusive OR of the pixel group of the original data to be detected in FIG. 6 and the pixel group in which the inside of the contour thus obtained is filled in, the pixel group indicated by 31 in FIG. 10 can be extracted. This pixel group is a closed region in the original data, which is not filled.

Now, by taking the exclusive OR, it is possible to extract the partial area which is not originally filled. Here, this closed region can be considered to be in the same state as the pixel group 27 in FIG. In the present embodiment, the case where there are a plurality of regions with contours inside the region of interest, which is the original data, is clear, but it is clear that they usually do not always exist. Ends immediately. Returning to FIG. 10, the pixels in the detection area are sequentially examined again, and the first non-zero pixel is searched. After that, similarly to the processing of FIG. 7, the pixel group located in the contour portion can be detected along the locus 30 of the detection processing of FIG. Furthermore, as shown in FIG. 12, the contour line 32 of the inner area can also be extracted. The closed area surrounded by this contour is filled with a pixel group using the filling hardware (3 in FIG. 13).
When the exclusive OR of 3) and the pixel group (31 in FIG. 10) obtained by the exclusive OR calculation last time is taken,
As shown in FIG.
Can be extracted. Also for this last pixel group 34, if the processing shown in FIG. 3 is performed (the processing process is shown in FIG. 15), the contour line (36 in FIG. 16) is obtained. As described above, even if many contour lines to be obtained exist inside the pixel data of interest, it is possible to finally obtain all the contour lines by repeating the above operation a plurality of times.

[0021]

As is apparent from the above embodiments, the contour extracting means of the present invention makes it easy to detect the inner white area, so that all contours in the binarized image are It can be said that the extraction can be performed faster than the sequential detection method in which the same number of scans is performed for the number of pixels in the scanning direction and the hardware can be easily replaced.

[Brief description of drawings]

FIG. 1 is a block diagram of a contour extracting means of the present invention.

FIG. 2 is a flow chart of processing of the present invention.

FIG. 3 is a flow chart of a contour line extraction method.

FIG. 4 is an explanatory diagram of a contour line extraction method.

FIG. 5 is an explanatory diagram of an extracted contour line.

FIG. 6 is an explanatory diagram of original data for contour extraction.

FIG. 7 is an explanatory diagram of a process of first contour extraction.

FIG. 8 is an explanatory diagram of a contour line extracted first.

FIG. 9 is an explanatory diagram of filling the inside of the first extracted contour line.

FIG. 10 is an explanatory diagram of an exclusive OR of original data and pixel data in which the inside of the first extracted contour line is filled.

FIG. 11 is an explanatory diagram of a process of extracting an internal contour line of original data.

FIG. 12 is an explanatory diagram of one of the extracted internal contour lines.

FIG. 13 is an explanatory diagram of the extracted closed area surrounded by one of the internal contour lines.

FIG. 14 is an explanatory diagram of an exclusive OR of the pixel data initially obtained by taking the exclusive OR and a closed region surrounded by one of the internal contour lines.

FIG. 15 is an explanatory diagram of a process of extracting an internal contour line of original data.

FIG. 16 is an explanatory diagram of one of the extracted internal contour lines.

FIG. 17 is an explanatory view of a conventional inner contour detecting means.

[Explanation of symbols]

 25 Boundary of Detection Area 26 Trajectory of Detection Processing 27 Pixel Group of Original Data 28 Contour Line 29 Pixel Group after Filling Execution 31 Pixel Group by Exclusive OR Operation 32 Contour Line of Inner Area 52 Contour Extraction Section 53 Filling Section 57 Exclusive Logical OR circuit

Claims (1)

[Claims] 1. A device for extracting a contour of quantized image data, said means for obtaining an exclusive OR of a pixel group filling a closed region of the extracted contour and a closed region of interest. And a means for extracting the contour of the closed region which is extracted by exclusive OR and is present inside the contour of the closed region of interest and which is not filled. Extractor.