JPH0522598A - Picture input device - Google Patents

Abstract

PURPOSE:To easily correct an ineffective picture and a defective picture in a binary picture in a short time at the time of binarizing a gradation picture. CONSTITUTION:A threshold determining part 203 obtains a density histogram based on gradation picture data and determines a first threshold in accordance with this density histogram. A binarizing part 204 binarizes gradation picture data in accordance with the first threshold. A binary picture processing part 205 deletes the ineffective picture in binary picture data to generate binary picture data A. A gradation picture processing part 208 performs the filing processing of gradation picture data to prevent the defective picture. This gradation picture data is binarized to generate binary picture data B. A binary picture processing part 213 generates final binary picture data having no ineffective pictures neither defective pictures based on binary picture data A and B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input device such as a mount input device, and more particularly to an image input device for generating binary image data from inputted gradation image data.

[0002]

2. Description of the Related Art In a conventional plate making process and design layout, a mount is used as a designated paper for layout when laying out photographs and characters. CA the image on this mount
Although a photo layout frame or the like in an editing device such as a layout scanner is input by tracing using D or the like, a free graphic such as a map cannot be actually traced as a CAD graphic. In this case, by inputting the image on the mount using an image input device such as a flatbed scanner and recognizing an area for the input data, photographs, characters, etc. are laid out in this area. . Further, the color designation for the image line portion and the valid image, invalid image, and invalid region described later are designated.

A conventional image input device of this type will be described with reference to FIGS. FIG. 6 is a flowchart showing an operation procedure in the conventional image input device. Further, FIG. 7 is a diagram showing an invalid image in the binary image data, and FIG. 8 is a diagram showing a missing image in the binary image data.

In the conventional image input device, an original image on which a line drawing or the like is drawn is read as a gradation image by a scanner (S61). The read original image is binarized (S62) according to a predetermined threshold value (S65). S6
The threshold value determined in 5 is a fixed value, and binarization is performed on any original image (even if the shading of the original image changes) according to this threshold value.

However, as shown in FIGS. 7 and 8,
A point 70 (hereinafter referred to as an invalid image) that is not included in the original image may be mixed in the binarized binary image data due to stains on a paper surface (for example, a mount) on which the original image is drawn. is there. Further, since the density of a part of the line drawing drawn on the original image is low, a missing image 80 (hereinafter referred to as a missing image) is generated in the binary image data even though it is included in the original image. There is.

The invalid image or the missing image is removed by the operator correcting the binary image data (S63). For example, the binary image data is displayed on the display, and the operator visually compares the displayed image with the original image on the mount to delete the invalid image or complement the missing image portion. By adding such a correction instruction to the binary image data, the image area is validated or invalidated, and the boundary is recognized (S64). Then, this data is used in other steps as an area for laying out an image such as a photograph in a layout scanner or the like.

[0007]

However, in the conventional image input device, since the invalid image or the missing image is corrected by the operator's visual observation as described above, the skill of the operator is required. In addition, there is a problem that the correction work requires a long time.

[0008]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to easily correct an invalid image and a missing image of binary image data in an image input device in a short time.

[0009]

According to a first aspect of the present invention, there is provided an image input device which binarizes the input first gradation image data on the basis of a first threshold value and outputs the first binary image data. First image binarization means for generating image data, and first for removing frequency components higher than a first cutoff frequency in the first binary image data to generate second binary image data. A binary image processing means for removing the frequency component higher than the second cutoff frequency from the first gradation image data to generate second gradation image data; Second image binarizing means for binarizing the second gradation image data based on a threshold value of 2 to generate second binary image data, the first binary image data and the second binary image data. Second binary image data based on the second binary image data Characterized in that it has an image processing means.

In the image input device according to the second aspect of the present invention, the first threshold value is set based on the input first gradation image data.

Further, in the image input apparatus according to the invention of claim 3, the second threshold value is set based on the second gradation image data.

[0012]

In the image input apparatus according to the first aspect of the present invention, the first image binarizing means binarizes the input first gradation image data based on the first threshold value, To generate binary image data of. The first binary image processing means removes a frequency component higher than a first cutoff frequency from the first binary image data to generate second binary image data. For example, the single pixel (invalid image) mixed at the time of input is deleted. The gradation image processing means removes a frequency component higher than the second cutoff frequency from the first gradation image data to generate second gradation image data. The second image binarization unit binarizes the second gradation image data based on the second threshold value to generate second binary image data. Thereby, for example, the first
This is to interpolate the line drawing part that is missing by filtering at the cutoff frequency of. Then, the second binary image processing means includes the first binary image data and the second binary image data.
The third binary image data is generated based on the binary image data of. As a result, the invalid image is deleted and the missing image is interpolated.

An image input device according to a second aspect of the present invention is the image input device according to the first aspect, wherein the first threshold value is set based on the input first gradation image data. For example, a histogram is created based on the input image data, and the threshold value is set for each input data by this histogram. As a result, the number of missing images in the original image is reduced, and the mixing of invalid images is significantly reduced.

An image input apparatus according to a third aspect of the present invention is the image input apparatus according to the first aspect, wherein the second threshold value is set based on the second gradation image data. For example, a histogram based on gradation is created in the same manner as described above, and the second threshold value is set based on this histogram. As a result, the invalid image can be removed and the missing image can be interpolated with higher accuracy.

[0015]

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

FIG. 1 is an external view of an image input device according to the first embodiment of the present invention. The image input apparatus according to the first embodiment includes a flat bed type image scanner 11, a computer main body 12, a display 13, a magnetic disk unit 14, a magneto-optical disk unit 15, and a mouse 16. It is configured.

The image scanner 11 reads an original image such as a line drawing drawn on a mount. The original image read by the image scanner 11 is input to the computer main body 12 and simultaneously output to the display 13. The operator uses the display 13, the mouse 16, etc. to binarize the original image according to the program stored in the magnetic disk 14. This binary image data is written and stored in the magneto-optical disk in the magneto-optical disk unit 15.

FIG. 2 is a functional block diagram of the image input apparatus according to this embodiment. As shown in FIG. 2, the image input device includes an image input unit 201, a gradation image storage unit 202, and a gradation image storage unit 202.
09, the binary image storage units 204, 206 and 211, the gradation image processing unit 208, the binarization units 203 and 210, the binary image processing units 205, 210 and 213, and the threshold value determination unit 2.
07 and 212 and an information adding unit 213.

The image input section 201 is composed of the image scanner 11, and the original image is read and input as a gradation image by the image input section 201. The input original image data is A / D converted. The A / D converted image data is represented by, for example, 4 bits (16 gradations). This 4-bit image data is stored in the gradation image storage unit 2
No. 02 is stored.

The threshold value determining unit 207 determines the first threshold value based on the gradation image data stored in the gradation image storage unit 202. The binarization unit 203 binarizes the gradation image data stored in the gradation image storage unit 202 according to the first threshold. This binary image data is input to and stored in the binary image storage unit 204. The binary image processing unit 205 performs processing such as deleting an invalid image in the binary image data. The processed binary image data is stored in the binary image storage unit 206.

On the other hand, the gradation image processing unit 208 performs processing such as filtering on the gradation image data stored in the gradation image storage unit 202. The processed gradation image data is stored in the gradation image storage unit 209. The threshold value determining unit 212 determines the second threshold value based on the gradation image data stored in the gradation image storage unit 209. Binarization unit 210
Performs binarization on the gradation image data stored in the gradation image storage unit 209 according to the second threshold value. This binary image data is stored in the binary image storage unit 211.

The binary image processing unit 213 determines the final binary image data based on the binary image data stored in the binary image storage unit 206 and the binary image data stored in the binary image storage unit 211. To generate. The information adding unit 214 adds necessary data other than the binary image data to the final binary image data.

The threshold value determination unit 207 and the binarization unit 20
3. The binary image storage unit 204 forms a first image binarization unit according to the image input device of the first aspect. Similarly, the binary image processing unit 205 and the binary image storage unit 206 form a first binary image processing unit. The gradation image processing unit 208 and the gradation image storage unit 209 form a gradation image processing unit. A binarization unit 210, a binary image storage unit 211,
The threshold value determining means 212 forms a second image binarizing means. The binary image processing unit 213 forms a second binary image processing unit.

Next, the operation of the image input apparatus according to this embodiment will be described with reference to FIGS.

FIG. 3 is a flow chart showing the operation of the image input apparatus according to this embodiment. 4 (A) to 4 (C)
FIG. 4 is a diagram showing a histogram of an original image, gradation image data, and a gradation image data, respectively. Figure 5 (A)
5C is a diagram showing the gradation image data, the binary image data A, and the final binary image data that have been processed by the two-dimensional low-pass filter.

First, the original image shown in FIG. 4A is input to the image input device (S301). The data of the original image is represented by 4-bit gradation image data and stored in the gradation image storage unit 202, as shown in FIG.

Next, the threshold value deciding unit 207 follows the gradation image data stored in the gradation image storage unit 202, as shown in FIG.
A density histogram of (C) is created (S302). In general, this density histogram has a peak a in low density data indicating a blank portion of the original image, as shown in FIG. Further, the high-density data showing the streak portion of the original image also has a peak b.

The threshold determination unit 207 determines the first threshold based on this histogram (S303). The determination of the first threshold value follows the procedure below. That is, FIG. 4 (C)
The midpoint c between the two peaks a and b in the density histogram shown in FIG. Further, an intermediate point d between the intermediate point c and the peak b is obtained, and the density at the intermediate point d is set as the first threshold value. This is because the image area usually has a constant density, and therefore, by making the threshold value closer to the density area side of the image area, it is possible to remove a stain portion or the like having a density equal to or lower than the image area density. . However, the determination of the threshold value is not limited to the above method and can be appropriately selected.

The binarization unit 203 binarizes the gradation image data stored in the gradation image storage unit 202 according to the first threshold value to generate binary image data (S304). Since the first threshold value is determined in this way, it is possible to more accurately remove, for example, the inclusion of an invalid image in the binary image data without being affected by the change in the shading of the entire original image.

The binary image processing section 205 detects data (single pixel data) in which only the central pixel data of the adjacent 3 × 3 pixel data is “1” among the binary image data, and The individual pixel data is set to "0" (S30
5). That is, the binary image processing unit 205 constitutes a two-dimensional low-pass filter, and by deleting the high frequency component (single pixel data) which is a component higher than the first cutoff frequency according to claim 1, You can remove invalid images. This is because the single pixel data is often an invalid image. The binary image processing unit 205 that extracts an invalid image is not limited to the method using the above two-dimensional low-pass filter. For example, a method of extracting invalid pixels by determining whether or not a pixel and an adjacent pixel have the same value may be used. Furthermore, by appropriately selecting the first cutoff frequency, it is possible to delete, for example, 2 × 2 invalid images limited to single pixel data. The invalid image is deleted, and the generated binary image data A is stored in the binary image storage unit 206 (S306).

On the other hand, the gradation image processing unit 208 removes frequency components higher than the second cutoff frequency according to claim 1 from the gradation image data stored in the gradation image storage unit 202. Dimensional low-pass filter processing (S
307). For this two-dimensional low-pass filter, for example, a simple method of obtaining an average value of adjacent 3 × 3 data can be used. By performing such filtering processing on the gradation image data, as shown in FIG.
In the gradation image data of (C), the density of the portion 41 having a relatively low density is high. Therefore, it is possible to prevent a missing image due to binarization of the filtered gradation image. Note that the gradation image processing unit 208 is not limited to such a two-dimensional low-pass filter,
Other two-dimensional low pass filters may be used.
Furthermore, by appropriately selecting the second cutoff frequency, it is possible to complement a missing image of any size. The gradation image data that has been filtered is
It is stored in the gradation image storage unit 209.

A density histogram of the gradation image data stored in the gradation image storage unit 209 is created by the same method as S302 (S308). Further, similarly to S303, the second threshold value is obtained from this density histogram (S309). The gradation image data stored in the gradation image storage unit 209 is binarized according to the second threshold value (S310) to generate the binary image data B (S31).
1). The binary image data B is stored in the binary image storage unit 211. The binary image data B has fewer missing images than the binary image data A.

In the binary image data A, the invalid image is deleted, but the process for preventing the missing image is not performed. Therefore, the binary image data A has the missing images 51 and 52 as shown in FIG. 5B. There is. On the other hand, since the gradation image data shown in FIG. 5 (A) has been processed by the two-dimensional low-pass filter, the binary image data B obtained by binarizing the gradation image data is shown.
Does not include the missing images 51 and 52, but an image that is equal to or higher than the second threshold due to the filtering process is equal to or lower than the second threshold (missing images 53 to 56), or includes an invalid image. There is a case. In this way, based on the binary image data A and B composed of different data, the final binary image data is obtained according to the following procedure (S312, S313).

First, the logical product data of the binary image data A and the binary image data B is obtained. The data in the binary image data B corresponding to the data of "1" in the data of the logical product and the data adjacent to the data and having the data of "1"
Data in the binary image data B is extracted (S31
2). In this way, the data of the logical sum of the data in the binary image data B extracted and the binary image data A is obtained, and the data of this logical sum is used as the final binary image data of FIG. 5C. (S313). Therefore, the missing images 53 to 56 of FIG. 5A and the missing images 51 and 52 of FIG.
It is interpolated in the final binary image of FIG. Further, the final binary image data is added with a valid / invalid instruction as an image line portion and necessary data for recognition as a boundary portion of the area (S314).

By executing the above flow chart, the final binary image data that does not include the invalid image and the missing image is automatically obtained. In addition, in the binary image processing unit 705 that extracts invalid images, in addition to the method using the two-dimensional low-pass filter described above, it is determined whether or not a pixel and an adjacent pixel have the same value, and this work is performed one after another. By doing so, a method for extracting a single pixel or the like can be appropriately selected.

[0036]

As described above, according to the present invention, the invalid image of the binary image and the defective image can be easily corrected in the image input device in a short time. .

[Brief description of drawings]

FIG. 1 is an external view of an image input device according to a first embodiment of the invention.

FIG. 2 is a functional block diagram of the image input apparatus according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing an operation of the image input device according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an original image, gradation image data, and a density histogram of gradation image data according to the first embodiment of the present invention.

FIG. 5 is a diagram showing gradation image data, binary image data A, and final binary image data that have been processed by the two-dimensional low-pass filter according to the first embodiment of the present invention.

FIG. 6 is a flowchart showing an operation procedure in a conventional image input device.

FIG. 7 is a diagram showing an invalid image in binary image data.

FIG. 8 is a diagram showing a missing image in binary image data.

[Explanation of symbols]

203 Binarization unit (first image binarization means) 204 Binary Image Storage Unit (First Image Binarization Unit) 205 Binary Image Processing Unit (First Binary Image Processing Unit) 206 Binary Image Storage Unit (First Binary Image Processing Unit) 207 Threshold value determination unit (first image binarization unit) 208 gradation image processing unit (gradation image processing unit) 209 gradation image storage unit (gradation image processing unit) 210 Binarization Unit (Second Binarization Means) 211 Binary image storage unit (second binarizing means) 212 Threshold Determining Means (Second Binarizing Means) 213 Binary Image Processing Unit (Second Binary Image Processing Unit)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Suzuki             1-5-1 Taito, Taito-ku, Tokyo Toppan stamp             Imprint Co., Ltd.

Claims (3)

[Claims] 1. A first image binarizing unit which binarizes the input first gradation image data based on a first threshold value to generate first binary image data, and the first image binarizing unit. First binary image processing means for removing frequency components higher than the first cutoff frequency from the binary image data, and generating the second binary image data; and the first gradation image data, A gradation image processing unit that removes frequency components higher than the second cutoff frequency and generates second gradation image data, and binarizes the second gradation image data based on a second threshold value. Second image binarization means for generating second binary image data, and third binary image data based on the first binary image data and the second binary image data. Second binary image processing means for 2. The image input device according to claim 1, wherein the first threshold value is set based on the input first gradation image data. 3. The image input device according to claim 1, wherein the second threshold value is set based on the second gradation image data.