JPH05145739A - Method and device for processing of hollowed image - Google Patents

Abstract

PURPOSE:To reduce the generation of the visually offensive patterns by comparing the noted image data with the reference picture element data including a pattern of a hollow part in an inside area for extraction of the peripheral contour of a noted picture element. CONSTITUTION:The input image data are converted into the binary data having a bit per picture element by a binarization processing part 3. Then a noted picture element and the picture elements included in the peripheral areas of the noted picture element are stored in a buffer 4 as the noted picture element data among those binarized image data. The noted image data stored in the buffer 4 is sent to a contour extracting part 5, and the matching of patterns is secured between the noted image data and the reference picture element data having a pattern of a hollow part in an inside area against the noted image data. Thus a peripheral contour of the noted picture element is extracted and a contour image is outputted onto the noted picture element. Thus it is possible to reduce the generation of the visually offensive patterns when a halftone dot image, etc., are hollowed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow image processing method and apparatus for digital copying machines, printers and the like.

[0002]

2. Description of the Related Art As a conventional image processing apparatus for providing a hollow image, for example, as a first conventional example thereof,
There is one disclosed in Japanese Patent Application Laid-Open No. 58-117773 under the title of "Image signal binarizing apparatus". That is, the analog image data is binarized by three types of binarizing means, and the binarization information corresponding to a plurality of pixels surrounding the target pixel in the original image is sequentially clipped by the clipping circuit. The analog image data is binarized by detecting the logical product state in the information by the detection circuit.

Further, as a second conventional example thereof, Japanese Patent Laid-Open No.
There is one disclosed in the 3-108860 publication under the title of "image editing apparatus". This is because in an image editing apparatus that extracts contour information based on the amount of change in density of adjacent pixels, an edge is detected by an edge enhancement filter for each pixel, and the threshold value of the binarizing means is used by using the detected value. The contour extraction processing is performed by binarizing the contour information.

[0004]

In the image processing in the first conventional example, the image data is compared with a reference pixel pattern having a hollow portion in the internal area. Since no processing is performed, the number of pixels increases, which causes a problem that the device becomes large. Further, in the case where the outline removal processing of the image data as in the second conventional example is performed and the outline width (the border width when the outline removal processing is performed) is made large, the reference pixel for the outline detection processing. It is necessary to increase the size of the pattern, etc., which causes a problem that the scale of the device for realizing the hollowing process increases. Furthermore, when the image 1 having the halftone dots as shown in FIG. 8 is subjected to the hollowing-out process by the conventional method, a large number of isolated halftone dots 2 exist in the internal area as shown in FIG. Such a pattern will be generated.

[0005]

According to a first aspect of the present invention, image data is binarized, and a pixel of interest in the binarized image data and peripheral pixels in a peripheral region of the pixel of interest are focused. The target image data is stored as image data, and the target image data is compared with reference pixel data having a hollow portion pattern in the inner region with respect to the target image data to extract a contour around the target pixel and a contour on the target pixel. Output the image.

According to the second aspect of the present invention, the image data is set to 2
Binarization processing means for binarizing is provided, and storage means is provided for storing the pixel of interest in the binarized image data and peripheral pixels in the peripheral region of the pixel of interest as the image of interest, the image of interest. A contour extracting means is provided for comparing the data with the reference pixel data having a hollow pattern in the inner area of the target image data to extract the contour around the target pixel.

[0007]

According to the first aspect of the present invention, it is possible to reduce the occurrence of visually noticeable patterns that occur when the half-tone dot image or the like is subjected to the hollowing process.

According to the second aspect of the present invention, the contour extraction means has a smaller number of pixels in the pattern of the reference pixel data as compared with the conventional method, so that the scale of the apparatus can be reduced by that amount.

[0009]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a hollow image processing device. The present apparatus includes a binarization processing unit 3 as a binarization processing unit that binarizes image data, a pixel of interest in the binarized image data, and peripheral pixels in a peripheral region of the pixel of interest. Is stored as target image data, and the target image data is compared with reference pixel data having a hollow portion pattern in the internal region with respect to the target image data, and the contour around the target pixel is compared. And a contour extracting section 5 as a contour extracting means for extracting

In such a configuration, first, the input image data is converted by the binarization processing unit 3 into binary data of 1 bit per pixel. The target pixel in the binarized image data and the peripheral pixels in the peripheral area of the target pixel are stored in the buffer 4 as the target image data. Then, the image data of interest stored in the buffer 4 is sent to the contour extracting section 5 to perform the following processing. That is, pattern matching is performed between the target image data and the reference pixel data having a pattern of hollow portions in the target image data.
At this time, when a contour is detected in the content of the binarized data read within the range of the pattern of the reference pixel data, the logical product of the contour and the content of the pixel of interest at this time is obtained, and the position where the pixel of interest is active ( A contour image is generated (inside the image).
The width of the contour image at this time is determined by the shape (size) of the peripheral portion of the pattern of the reference pixel.

Next, a specific example of this apparatus will be described.
In FIG. 2, a pattern in which only the pixels at the outermost periphery of the matrix in the square matrix of size 5 × 5 are left is the reference pixel 6 (peripheral pixel), and the pixel located at the center of the matrix is the target pixel 7. .. Further, FIG. 3 shows a configuration example of the buffer 4. This buffer 4
Are 5 × 5 latches 4-1 and 4-2 arranged in rows and columns.
5 and four memories 4-26 to 4 for one line of the input image
It consists of -29. Further, FIG. 5 shows a configuration example of the contour extracting unit 5. The contour extracting unit 5
It is composed of an X-OR circuit 8 and an AND circuit 9. On the input side of the EX / OR circuit 8, the latches 4-1 to 4,5, 4-6, 4-10, located in the outermost peripheral area of FIG.
4-11, 4-15, 4-16, 4-20, 4-21-
The input 8a sent from 4-25 is connected. Further, the input side of the AND circuit 9 is connected to the input 9a sent from the latch 4-13.

In such a configuration, as input image data, 8 bits of digital monochromatic image data are input to the binarization processing unit 3, and binarization processing is performed by this. In this case, the binarization method is the 8-bit MSB of the input data.
When is "1", the binarized data is set to "1" and MSB
When is "0", the binarized data is "0".
Next, with respect to the image data binarized in this way, the target pixel 7 to be processed and the reference pixel 6 which is the data around it are stored in the buffer 4. In this case, as shown in FIG. 3, the latch 4-at the position corresponding to the reference pixel
1 to 4-5, 4-6, 4-10, 4-11, 4-15,
The contents of 4-16, 4-20, 4-21 to 4-25 and the latch 4-13 at the position corresponding to the pixel of interest 7 are sent to the contour extracting unit 5. In the contour extracting unit 5, as shown in FIG. 4, the contents of the input 8a of the EX / OR circuit 8 are the contents of the latches 4-1 to 4-5, 4-6, 4-10, 4-11, 4-11 of FIG. Four
-15, 4-16, 4-20, 4-21 to 4-25 (these are referred to as a peripheral latch group), and A
The content of the input 9a of the ND circuit 9 corresponds to the content of the latch 4-13. The output 8b of the EX / OR circuit 8 is
The contents of the peripheral latch group are uniform (the contents of each latch are all "
If it is not 0 "or" 1 "), it becomes" 1 ". The output 9b of the AND circuit 9 is the output 8b of the EX / OR circuit 8 and
Moreover, it becomes "1" only when the input 9a from the latch 4-13 corresponding to the target pixel 7 is "1". Therefore, this means that when the content of the image data is the content of the reference pixel 6 in which the entire area is not uniform and the edge is present and the content of the pixel of interest 7 is "1", the output 9b of the AND circuit 9 is output. Is "
1 ”. In such a state, the output 9b is output as a contour image on the pixel of interest 7.
In FIG. 3, the contents of the latches 4-1 to 4-25 are assumed to be shifted by the clock synchronization signal input to the buffer 4 for each of the above-mentioned processes. Further, when the target pixel 7 is located near the edge of the image and the input image does not exist within the range of the reference pixel pattern 6, the edging image is not output as a prohibition rule.

As described above, by performing a series of operations using all the pixels of the input image as the target pixel 7, it is possible to realize the hollowing process of the input image. Further, in the processing of the contour extraction unit 5, the number of reference pixels 6 in the image data shown in FIG. 2 is smaller than that of the conventional one, so that the scale of the apparatus can be reduced accordingly. For example,
The number of input terminals of the EX-OR 8 in FIG. 4 is 25 in the conventional method, but is reduced to 16 in the present embodiment. The effect of such reduction becomes more remarkable as the pattern size of the reference pixel 6 becomes larger (the contour image having a wider width is synthesized). Note that a contour that is sufficiently larger than the hollow portion inside the pattern of the reference pixel 6 is contour-extracted as in the conventional method, and thus a contour image having the same width as in the conventional method can be obtained.

Further, in the contour extracting unit 5, since the internal area of the reference pixel pattern is a hollow portion, the image 10 as shown in FIG. 5 in which a contour smaller than the hollow portion exists is subjected to a hollowing process. In this case, in the conventional method, the contour image 11 remains as it is as shown in FIG. 7, whereas in the method of the present embodiment, the contour image 11 as shown in FIG.
Is less likely to occur. More specifically, when the hollowing-out process of the image 1 having a halftone dot in the flat portion as shown in FIG. 8 is performed, the halftone dot 2 remains as shown in FIG. 10 in the conventional method. In this method, as shown in FIG. 9, it is possible to provide a hollow image in which small noise and halftone dots 2 are unlikely to occur. Therefore, from the above, when compared to the conventional method, in small noises and halftone images on the original,
It is possible to reduce the occurrence of a contour image in a visually flat image area, which makes it possible to provide a more visually preferable hollowing process.

The means for the binarization processing is not limited to the method shown in the binarization processing unit 3 as described above. As the shape of the reference pixel pattern 6, not only a square matrix as shown in FIG. 2 but also a shape such as a circle or a polygon can be freely selected, and the width of the outer periphery of the reference pixel pattern 6 is the outermost peripheral portion. Need not be one pixel. Further, the present apparatus is not limited to the hollowing process, but can be used for the contour detection which is the process. Furthermore, the input image data is not limited to a single color image, and a full color image can be easily expanded.

[0016]

According to the first aspect of the present invention, the image data is transferred to 2
The target pixel of the binarized image data and the peripheral pixels in the peripheral region of the target pixel are stored as target image data, and the target image data and the target image data are stored in the internal region. Since the outline around the pixel of interest is extracted by comparing with the reference pixel data having the pattern of the hollow portion and the outline image is output on the pixel of interest, when performing the hollowing-out process on the halftone image or the like. In addition, it is possible to reduce the occurrence of visually noticeable patterns.

According to a second aspect of the present invention, there is provided binarization processing means for binarizing the image data, and the pixel of interest in the binarized image data and peripheral pixels in the peripheral region of the pixel of interest are provided. Is provided as image data of interest, and the image of interest is compared with reference pixel data having a pattern of hollow portions in the internal region of the image of interest to extract the contour around the pixel of interest. Since the contour extracting means is provided, the contour extracting means reduces the number of pixels in the pattern of the reference pixel data as compared with the conventional method without impairing the effect of the blanking process, that is, without changing the blanking width. This makes it possible to reduce the load on the device and reduce the size of the device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a hollow image processing device which is an embodiment of the present invention.

FIG. 2 is a front view showing a state of a reference pixel pattern having a hollow portion in an internal region.

FIG. 3 is a circuit diagram showing an internal configuration of a storage unit.

FIG. 4 is a circuit diagram showing an internal configuration of contour extracting means.

FIG. 5 is a schematic diagram showing a state of an image pattern in which a contour smaller than a hollow portion is present.

FIG. 6 is a schematic diagram showing a state in which the image pattern of FIG. 5 is subjected to hollowing processing by the present method.

FIG. 7 is a schematic diagram showing a state in which the image pattern of FIG. 5 is subjected to hollowing processing by a conventional method.

FIG. 8 is a front view showing a state of an image pattern when a flat portion has halftone dots.

9 is a front view showing a state in which the image pattern of FIG. 8 is subjected to hollowing processing by the present method.

FIG. 10 is a front view showing a state where the image pattern of FIG. 8 is subjected to hollowing processing by a conventional method.

[Explanation of symbols]

 3 binarization processing means 4 storage means 5 contour extraction means 6 peripheral pixels 7 target pixel

Claims (2)

[Claims] 1. The image data is binarized, and a pixel of interest in the binarized image data and peripheral pixels in a peripheral area of the pixel of interest are stored as image data of interest, and the image data of interest and the pixel of interest are stored. It is characterized in that the target image data is compared with reference pixel data having a hollow pattern in an internal region to extract a contour around the target pixel and output a contour image on the target pixel. Hollow-out image processing method. 2. A binarization processing means for binarizing the image data is provided, and a pixel of interest in the binarized image data and peripheral pixels in a peripheral region of the pixel of interest are stored as the image data of interest. And a contour extraction unit that compares the target image data with reference pixel data having a hollow portion pattern in the inner region of the target image data to extract a contour around the target pixel. A hollow image processing device characterized by the above.