KR19980066127A - Binarization Method Using Directionality - Google Patents

Abstract

end. The technical field to which the invention described in the claims belongs

The present invention relates to a binarization method using directionality.

I. The technical problem that the invention is trying to solve

The binarized image is smoothed and softened according to the orientation of the image data.

All. Summary of Solution of the Invention

A directional retrieval step of retrieving whether the image corresponding to the 3x3 mask has directionality; if the image has directionality, the image is binarized using a 3x3 threshold mask configured according to the directionality in advance; Otherwise it comprises a binarizing step of binarizing in a global critical manner.

la. Important uses of the invention

Used to process image data.

Description

Binarization Method Using Directionality

The present invention relates to an image data processing method, and more particularly, to a binarization method of image data.

In general, in order to transmit and receive multi-gradation image data output from a scanner or the like, binarization is required to convert the image data into 0 and 1 image data.

Conventional binarization methods include a global threshold method and a local threshold method. As an example of the global threshold method, when binarizing multi-gradation text image data of 256 levels, binarization is performed using an intermediate value of 128. The local threshold method is to apply a 3x3 mask to the image data and binarize the threshold between the maximum and minimum values of the brightness of the mask.

By the way, when binarizing text documents using the global threshold method, blurry letters and the like have been completely ignored. Also, the background and the text are not distinguished when the background and the text on the background are similar in color. And, the local threshold method is sensitive to noise, so the outline of text is not smooth.

In the conventional binarization method as described above, the binarization is performed by providing about three lines of memory in accordance with factors such as price. As a result, even when there were consecutive black dots, the black dots on one line and the black dots on the next line were not related to each other. Accordingly, two consecutive points are randomly arranged by binarization by different threshold values.

As described above, the conventional binarization method has a problem in that the binarized image data is irregularly arranged by binarizing the successive images by different threshold values.

Accordingly, it is an object of the present invention to provide a binarization method using orientation that makes the image smooth and smooth after binarization according to the orientation of the image data.

1 is a block diagram of a conventional facsimile;

2 is a flowchart of a binarization method using directionality according to a preferred embodiment of the present invention.

The present invention for achieving the above object is a direction search step for searching whether the image corresponding to the 3 × 3 mask has a direction, and if the image has a direction using a 3 × 3 threshold mask configured according to the direction in advance Binarizing the image, and binarizing the image in a global critical manner if the image has no orientation.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the annexed drawings, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. And a detailed description of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

The present invention can be applied to a device equipped with a scanner or any device that binarizes image data. Hereinafter, an example in which the present invention is applied to a facsimile, which is one of apparatuses having a scanner and binarizing image data output from the scanner, will be described.

1 illustrates a block diagram of a conventional facsimile, and the controller 10 controls the overall operation of the facsimile according to a preset program. The modem 12 modulates the image data output to the image processing unit 26 in the transmission mode in the transmission mode under the control of the control unit 10, and demodulates the image data to the image processing unit 26 in the reception mode. . The network control unit (NCU) 14 forms a transmission / reception path between the telephone line and the modem 12 under the control of the control unit 10. The printer 16 prints an image according to the image data provided by the image processing unit 26 on a sheet when the reception mode and the copy mode are executed under the control of the control unit 10. The memory 18 includes a program memory for storing a program and a data memory for temporarily storing data generated during the execution of the program. The scanner 20 scans an original under the control of the control unit 10. The operation panel 22 includes a plurality of keys and a display device for interfacing between the user and the control unit 10. The sensor unit 24 senses various states of the facsimile, and provides the sensing data accordingly to the controller 10. The image processor 26 receives image data under the control of the controller 10 and binarizes the image data and outputs the binarized data. In this case, the image processor 26 outputs the data after binarizing the image data according to the binarization method according to the present invention.

2 is a flowchart illustrating a binarization method according to an exemplary embodiment of the present invention performed by the image processor 26. In operation 28 of FIG. 2, the image processor 26 receives image data generated by scanning. When the reception of the image data is finished, the image processing unit 26 puts a 3x3 mask on the image data. Table 1 shows a 3x3 mask.

① ② ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨

In Table 1, ① to ⑨ indicate a gray value of each pixel. The image processor 26 calculates sum 1 to sum 2 according to Equation 1 in the above ① to ⑨.

When the calculation of sum 1 to sum 9 is completed, the image processor 26 calculates sub 1 to sub 4 according to Equation 2.

The image processing unit 26 performs step 34 when the calculation of sub 1 to sub 4 is finished. In step 34, the image processor 26 searches whether the maximum value of sub 1 to sub 4 is greater than a specific threshold. At this time, the image processor 26 determines that there is the directionality of the contour when the maximum value of the sub 1 to the sub 4 is larger than the specific threshold, and performs step (36), otherwise performs step (38). In step (36), the image processing unit 26 performs binarization using a 3x3 mask according to the maximum value.

The binarization is described in more detail as follows.

If the image data in the 3x3 mask is as shown in Table 2, the image has an edge and the edge is darkened to the right.

151 35 40 149 31 45 149 30 53

Since the image to be binarized has an edge which is darkened to the right as described above, the threshold value in the 3x3 mask should correspond to the above characteristic. Table 3 shows a 3x3 mask having a threshold value corresponding to the above characteristics.

100 200 170 100 200 170 100 200 170

In order to binarize as described above, the present invention includes a 3x3 threshold mask according to each case. That is, in the case of sum1sum2, in the case of sum1sum2, in the case of sum3sum4, in the case of sum3sum4, in the case of sum5sum6, and in the case of sum5sum6, a plurality of 3x3 threshold masks are provided.

When the binarization using the 3x3 threshold mask is finished, the image processor 26 performs step 40. In step (38), the image processing unit 26 performs binarization in a general global threshold method. When the binarization ends, the image processor 26 performs step 40. In step 44, the image processor 26 outputs binarized image data.

As described above, the present invention performs binarization according to the orientation of the image when binarizing the image data. This makes the image after binarization smooth and soft.

As described above, the present invention has the advantage that the image after binarizing by binarizing according to the orientation of the image data is smooth and soft.

Claims (1)

In the binarization method using directionality, a directionality searching step of searching whether an image corresponding to a 3x3 mask has directionality, and if the image has directionality, use the 3x3 threshold mask configured according to directionality in advance. And a binarizing step for binarizing and binarizing the image if the image has no orientation.