KR20220127978A - Apparatus and method for generating black-and-white image by preserving halftone pattern of image from color image separated by CMYK color space - Google Patents

Abstract

The present invention relates to an apparatus and a method for generating a black and white image by preserving a halftone dot pattern of an image from a color image separated from a printer into a CMYK color space. The method includes the following steps of: separating an inputted CMYK image into a CMY color image and a K black and white image; analyzing a halftone dot ratio and halftone dot pattern for each of the separated CMY color images, removing halftone dots for each of the CMY color images using the analyzed halftone dot ratio and the halftone dot pattern, and then generating one single black and white image; and outputting a black-and-white image for printing by calculating the generated one single black and white image and the separated K black and white image. Therefore, the present invention is capable of improving the quality of a black and white printout, and shortening time for generating a black and white image.

Description

Apparatus and method for generating black-and-white image by preserving halftone pattern of image from color image separated by CMYK color space}

The present invention relates to a printing apparatus, and more particularly, to an apparatus and method for generating a black and white typesetting surface image for printing by preserving halftone dots of a color image from a color image separated in a CMYK color space in the printing apparatus.

In general, a person who wants to place an advertisement in a newspaper or the like requests an advertisement while submitting a photo film generated by separating the advertisement contents in a CMYK color space to a newspaper company. A newspaper company scans this photographic film to create a typesetting image for printing, transfers the generated typesetting image to the film, and finally prints it on the paper.

'CMYK' is a type of color model and consists of cyan, magenta, yellow, and black. It is a standard color model used to synthesize colors in printing devices such as printers. . Random colors are expressed by mixing inks of four colors: cyan, magenta, yellow, and black.

Theoretically, all colors including black can be expressed by mixing inks of three colors: cyan, magenta, and yellow.

The color model as opposed to 'CMYK' is 'RGB', which is commonly used in display devices. 'RGB' consists of red, green, and blue.

TIFF (Tag Image File Format) is a popular format for exchanging raster images between applications, including scanned images.

A method of generating a black and white typesetting surface image for printing using a color image separated in a CMYK color space according to the prior art will be briefly described with reference to FIG. 1 .

1 is a diagram showing an operation flowchart of a process of converting an actual color image into a black-and-white image in a method of generating a black-and-white typesetting image for printing using a color image separated in a CMYK color space according to the prior art.

As shown in FIG. 1, after converting 4 1-bit/sample TIFF separated in CMYK color space into 4 8-bit/sample TIFF sheets (S101, S102), this is a 24-bit/sample RGB TIFF It is converted into an image (S103). Here, the halftone dot arrangement in the existing CMYK color space disappears, and the existing color information is converted to the RGB color model.

This RGB type TIFF image is again converted into a gray scale TIFF image (S104), and the halftone dot array is reproduced in the process of generating a 1-bit/sample TIFF by halftoning (S105). As for such a prior art, it is described in detail in the following prior patent documents, and detailed description is omitted.

In the above prior art, reproducing the halftone dot arrangement may have lower print quality than the method of removing halftone dots depending on the color while preserving the existing halftone dot pattern, and it takes a relatively long time to create while going through several steps of creation. do

Registered Patent Publication No. 10-0434901 (May 27, 2004)

Accordingly, the present invention is to solve the above problems, and an object of the present invention is to improve the print quality of a black-and-white page through a black-and-white image generated by utilizing the halftone dot arrangement of a color image, and to generate a black-and-white image for printing. An object of the present invention is to provide an apparatus and a method for generating a black-and-white image by preserving a halftone pattern of an image from a color image separated in a CMYK color space to shorten the image.

According to the present invention for achieving the above object, an apparatus for generating a black-and-white image by preserving a halftone pattern of an image from a color image separated into a CMYK color space according to the present invention is a printing apparatus, wherein the input CMYK image is converted into a CMY color image and a K an image separation unit that separates each black and white image; a halftone dot processing unit that analyzes a halftone dot ratio and a halftone dot pattern for each of the separated CMY color images, removes the halftone dots for each CMY color image using the analyzed halftone dot ratio and halftone dot pattern, respectively, and generates a single black-and-white image; and a calculator configured to calculate the generated single black-and-white image and the separated K black-and-white image to output a black-and-white image for printing.

The input CMYK image may be a TIFF image of 1 bit/sample .

The image generated by the halftone processing unit may be a 1-bit/sample black-and-white image.

The halftone processing unit calculates each halftone dot ratio for each color image of C and MY separated through the image separation unit, and a halftone point to be preserved and a halftone point to be removed for each CMY image analyzing each halftone dot pattern, respectively. a halftone dot ratio analysis and pattern analysis unit to be extracted; a halftone dot removal unit that maintains the halftone dots to be preserved and removes the halftone dots to be removed from the CMY image extracted through the halftone dot ratio analysis and pattern analysis unit; and a black-and-white image generation unit generating one 1-bit/sample black-and-white image by calculating each of the CMY images maintained through the halftone dot removal unit.

The black-and-white image generator may generate one 1-bit/sample black-and-white image by performing an OR operation on each of the CMY images.

In the halftone ratio analysis and pattern analysis unit, the halftone ratio analysis is performed by calculating the number of halftone dots having the color of the corresponding color in a reference rectangular area of 16 dots of 1 Byte (8bit) Х vertical 1Byte (8bit), and then using Equation 1 below. The number of halftone dots to be preserved can be obtained by multiplying the brightness ratio as shown.

In the pattern analysis of the halftone dots, after finding the center of the colored halftone dot and the non-colored halftone dot in the reference rectangular area, correction is performed when the halftone dot group spans other rectangular areas, The center point (X, Y) for the ? can be calculated using Equations 2 and 3 below.

The halftone dot removing unit may scan the CMY image in a spiral with respect to the center point of each halftone dot pattern to preserve the halftone dots to be preserved and remove the halftone dots to be removed.

On the other hand, the method for generating a black and white image by preserving the dot pattern of the image from the color image separated into the CMYK color space in the printing apparatus according to the present invention is to separate the input CMYK image from the CMY color image and the K black and white image. step; analyzing the halftone dot ratio and the halftone dot pattern for each of the separated CMY color images, removing each halftone point for each CMY color image using the analyzed halftone dot ratio and halftone dot pattern, and then generating one black and white image; and outputting a black-and-white image for printing by calculating the generated single black-and-white image and the separated K black-and-white image.

The input CMYK image may be a TIFF image of 1 bit/sample.

The image generated through the step of generating the black-and-white image may be a 1-bit/sample black-and-white image.

The step of generating the black-and-white image includes extracting each halftone dot ratio for each of the separated CMY color images, and a halftone point to be preserved and a halftone point to be removed for each CMY image analyzing each halftone dot pattern. step; maintaining the halftone dots to be preserved for the extracted CMY image and removing each halftone point to be removed; and generating one 1-bit/sample black-and-white image by calculating each of the maintained CMY images.

The generating of the black-and-white image may include generating one 1-bit/sample black-and-white image by performing an OR operation on each of the CMY images.

In the extracting step, the halftone dot ratio analysis is performed by obtaining the number of halftone dots having the color of the corresponding color in the reference rectangular area of 16 dots of 1 Byte (8bit) Х vertical 1Byte (8bit), and then the brightness ratio as shown in Equation 1 below. The number of dots to be preserved can be obtained by multiplying by .

In the extraction step, in the pattern analysis of the halftone dots, after obtaining the centers of the colored halftone dots and the non-colored halftone dots in the reference rectangular region, correction is performed if the halftone dot group spans other rectangular regions, and then the reference rectangular region The center point (X, Y) for the dotted pattern inside can be calculated using Equations 2 and 3 below.

In the step of removing each of the halftone dots, the halftone dots to be preserved may be preserved and the halftone dots to be removed may be removed by scanning spirally based on the center point of each halftone dot pattern for the CMY image.

According to the present invention, since a black-and-white image is generated while preserving the halftone pattern of the existing color image as much as possible, the print quality of the black-and-white page can be further improved and the generation time of the black-and-white image for printing can also be shortened.

The accompanying drawings below are provided to help understanding of the present embodiment, and provide embodiments together with detailed description. However, the technical features of the present embodiment are not limited to specific drawings, and features disclosed in each drawing may be combined with each other to constitute a new embodiment.
1 is a view showing an operation flowchart for a process of converting an actual color image into a black and white image in a method of generating a black and white typesetting image for printing using a color image separated in a CMYK color space according to the prior art;
2 is a block diagram of an apparatus for generating a black-and-white image by preserving a halftone pattern of an image from a color image separated in a CMYK color space according to the present invention;
3 is a diagram illustrating a detailed block configuration of the halftone dot processing unit shown in FIG. 2 ;
FIG. 4 is a diagram for explaining a method for analyzing a halftone dot pattern shown in FIG. 3 ;
5A to 5D are diagrams for explaining a process of converting a CMY color image into a CMY black-and-white image in which halftone dots are removed through analysis of a halftone dot pattern;
6 is a flowchart illustrating a method for generating a black-and-white image by preserving a halftone dot pattern of an image from a color image separated in a CMYK color space according to the present invention;

With respect to the embodiments of the present invention disclosed in this specification, specific structural or functional descriptions are only exemplified for the purpose of describing the embodiments of the present invention, and the embodiments of the present invention may be implemented in various forms and the text It should not be construed as being limited to the embodiments described in .

Since the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

When a component is referred to as being “connected” or “connected” to another component, it may be directly connected or connected to the other component, but it is understood that other components may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle. Other expressions describing the relationship between elements, such as "between" and "immediately between" or "neighboring to" and "directly adjacent to", etc., should be interpreted similarly.

The terms used herein are used only to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In this application, terms such as "comprise" or "have" are intended to designate that the disclosed feature, number, step, action, component, part, or combination thereof exists, but includes one or more other features or numbers, It should be understood that the possibility of the presence or addition of steps, operations, components, parts or combinations thereof is not precluded in advance.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

On the other hand, when an embodiment can be implemented differently, functions or operations specified in a specific block may occur differently from the order specified in the flowchart. For example, two consecutive blocks may be performed substantially simultaneously, or the blocks may be performed in reverse according to a related function or operation.

Each feature of the various embodiments of the present specification may be partially or wholly combined or combined with each other, technically various interlocking and driving are possible, and each embodiment may be independently implemented with respect to each other or may be implemented together in a related relationship. may be

Hereinafter, an apparatus and method for generating a black-and-white image by preserving a halftone dot pattern of an image from a color image separated in a CMYK color space according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of an apparatus for generating a black-and-white image by preserving a halftone dot pattern of an image from a color image separated in a CMYK color space according to the present invention.

As shown in FIG. 2 , the apparatus for generating a black-and-white image by preserving a halftone pattern of an image from a color image separated in a CMYK color space according to the present invention includes an image separation unit 100, a halftone dot processing unit 200, and an operation unit. (300) may be included.

When the CMYK color image is input, the image separation unit 100 separates the input CMYK color image into three CMY color images of 1-bit/sample and K black-and-white images of 1-bit/sample, and then separates each of the 1 bit/sample K black and white images. The three CMY color images of the sample are provided to the halftone processing unit 200 , and the K black and white images of 1 bit/sample are provided to the operation unit 300 . Here, it should be understood that the CMYK color image may be an image having a TIFF format, and is not limited to a TIFF image.

The halftone processing unit 200 converts each 1-bit/sample CMY color image separated from the image separation unit 100 into a single black-and-white TIFF image from which the halftone dots are removed, and then converts the converted black-and-white image into an operation unit ( 300) is provided. Here, a detailed operation of the halftone dot processing unit 200 will be described later in detail with reference to FIG. 3 .

The calculating unit 300 calculates one black-and-white image provided from the halftone dot processing unit 200 and the original K image, that is, the K-monochrome image separated by the image separation unit 100 to accurately reproduce the black image. It is to create a black-and-white TIFF image for printing in which the halftone pattern of the color image is preserved. Here, the operation unit 300 may perform a bitwise OR operation on one black-and-white image provided from the halftone dot processing unit 200 and the original K image to accurately reproduce black.

A detailed configuration and operation of the halftone dot processing unit 200 shown in FIG. 2 will be described in detail with reference to FIGS. 3 to 5 .

3 is a diagram showing a detailed block configuration of the halftone dot processing unit shown in FIG. 2 , FIG. 4 is a diagram for explaining the halftone dot pattern analysis method shown in FIG. 3 , and FIGS. 5A to 5D are CMY colors through halftone pattern analysis It is a diagram to explain the process of converting an image to a CMY black-and-white image with halftone dots removed.

3 , the halftone dot processing unit 200 illustrated in FIG. 2 may include a halftone dot ratio analysis and pattern analysis unit 210 , a halftone dot removal unit 220 , and a black and white image generation unit 230 . .

The halftone ratio analysis and pattern analysis unit 210 first analyzes the halftone dot ratio and the halftone dot pattern with respect to a rectangular area of a certain size for each CMY color image separately input from the image separation unit 100 shown in FIG. 1 . do. Here, the certain size should be larger than the size that can confirm the pattern of halftone dots, and it should be composed of multiples of bytes for operation speed. Therefore, in the present invention, a rectangular area of 16 dots of 1 byte (8 bits) horizontally and 1 byte (8 bits) vertical can be used for more detailed processing. Here, the halftone dot is an area of 1 dot and is expressed by 1 bit. 1 means a dot with color, and 0 means a dot without color.

In the halftone ratio analysis, the number of halftone dots having a color of a corresponding color is calculated in a rectangular area, and then the number of halftone dots to be preserved is obtained by multiplying the brightness ratio as in Equation 1 below.

The original colors Cyan, Magenta, and Yellow have luminance of 49%, 60%, and 7%, respectively. In order to convert this to a black and white image, the proportion occupied by the brightness is calculated, excluding the proportion occupied by the saturation in the original halftone dots of C, M, and Y.

The halftone dot pattern refers to an arrangement method of halftone dots constituting a color in a rectangular area.

The halftone dots that make up the color cannot express 1 Dot, which is 0.02mm in size, which exists independently due to the limitation of the printing device. Therefore, halftone dots are expressed as a group like a water droplet shape, which is called a halftone dot pattern.

The halftone pattern analysis is a method to find a halftone dot that needs to be removed while preserving the existing halftone dot pattern.

Here, the scanning technique is a method of reading physically continuous image data in a desired form in a logical manner.

In order to analyze the halftone pattern, as shown in FIG. 4 , a reference rectangular area and four rectangular areas surrounding the rectangular area are logically assumed and processed.

The five rectangular areas shown in FIG. 4 scan image data while sequentially moving. The reference rectangular area is the part where the halftone ratio analysis and the halftone pattern analysis are actually performed, and the four surrounding rectangular areas play an auxiliary role in finding the center in the halftone pattern analysis.

A group of dots may exist only in a blind area because their sizes are all different, but most of them exist over two or more blind areas.

First, the centers of the colored halftone dots and the non-colored halftone dots are found in five rectangular areas. Afterwards, if the group of halftone dots spans another blind area, a correction operation is performed as in Equation 2, and the center points (X, Y) of the halftone dot pattern in the reference rectangular area are calculated using Equations 2 and 3.

where (X, Y) = position of the center point of the reference rectangular area, (TX, TY) = position of the center point of the upper rectangular area, (BX, BY) = position of the center point of the lower rectangular area, (LX, LY) = The position of the center point of the left rectangular area, (RX, RY) = means the position of the center point of the right rectangular area.

When a center point is obtained for the halftone dot pattern as described above, information on the obtained center point is provided to the halftone dot removing unit 220 .

The halftone dot removal unit 220 scans the CMY image provided from the halftone ratio analysis and pattern analysis unit 210 in a spiral based on the center point of each halftone dot pattern to preserve the halftone dots to be preserved, and the halftone dots to be removed are Remove.

In addition, the halftone dot removal unit 220 provides the black-and-white image generator 230 with information on the rectangular area from which the halftone dots are removed for each CMY.

That is, the halftone dot removal unit 220 provides each 1-bit/sample image of the CMY color from which the halftone dots are removed as shown in FIGS. 5A to 5C to the black and white image generation unit 230 . Here, FIG. 5A is a diagram for explaining a state in which halftone dots are removed from a 1-bit/sample image of color C, and FIG. 5B is a diagram illustrating a state in which halftone dots are removed from a 1-bit/sample image of color M and FIG. 5C is a diagram for explaining a state in which halftone dots are removed from a 1-bit/sample image of Y color.

The black-and-white image generating unit 230 generates a black-and-white image for the CMY color image as shown in FIG. 5D in units of a rectangular area by ORing the images of each of the CMY colors from which the halftone dots are removed as shown in FIGS. 5A to 5C. .

When a black-and-white image from which halftone dots are removed for the CMY color image is generated, the black-and-white image generator 230 provides the corresponding image to the operation unit 300 illustrated in FIG. 2 .

The operation unit 300 performs an OR operation on the black-and-white image generated through the CMY color image and the 1-bit/sample K black-and-white image separated from the image separation unit 100 for expressing an accurate black color to 1 bit A printable black-and-white TIFF image of the /sample will be created.

A halftone dot pattern of an image from a color image separated into a CMYK color space according to the present invention corresponding to the operation of an apparatus for generating a black-and-white image by preserving the dot pattern of the image from the color image separated into the CMYK color space according to the present invention A method of generating a black-and-white image by preserving .

6 is an operation flowchart of a method of generating a black-and-white image by preserving a halftone pattern of an image from a color image separated in a CMYK color space according to the present invention.

As shown in FIG. 6 , when a CMYK color image is input first, the input CMYK color image is separated into three CMY color images of 1-bit/sample and K black-and-white images of 1-bit/sample (S601). It should be understood that the CMYK color image may be an image having a TIFF format, and is not limited to a TIFF image.

Then, the point ratio analysis and patterns are analyzed from the separated 1-bit/sample CMY color images (S602).

Let's take a look at the specific operation of the above-described step S602.

First, a halftone dot ratio and a halftone dot pattern of a rectangular area of a certain size are analyzed for each color image of CMY that is separately input. Here, the certain size should be larger than the size that can confirm the pattern of halftone dots, and it should be composed of multiples of bytes for operation speed. Therefore, in the present invention, a rectangular area of 16 dots of 1 byte (8 bits) horizontally and 1 byte (8 bits) vertical can be used for more detailed processing. Here, the halftone dot is an area of 1 dot and is expressed by 1 bit. 1 means a dot with color, and 0 means a dot without color.

In the halftone dot ratio analysis, the number of halftone dots having a color of a corresponding color is obtained in a rectangular area, and then the number of halftone dots to be preserved is obtained by multiplying the number of dots by a brightness ratio as in Equation 1 above.

The original colors Cyan, Magenta, and Yellow have luminance of 49%, 60%, and 7%, respectively. In order to convert this to a black and white image, the proportion occupied by the brightness is calculated, excluding the proportion occupied by the saturation in the original halftone dots of C, M, and Y.

The halftone dot pattern refers to an arrangement method of halftone dots constituting a color in a rectangular area.

The halftone dots that make up the color cannot express 1 Dot, which is 0.02mm in size, which exists independently due to the limitation of the printing device. Therefore, halftone dots are expressed as a group like a water droplet shape, which is called a halftone dot pattern.

The halftone pattern analysis is a method to find a halftone dot that needs to be removed while preserving the existing halftone dot pattern.

Here, the scanning technique is a method of reading physically continuous image data in a desired form in a logical manner.

In order to analyze the halftone pattern, as shown in FIG. 4 , a reference rectangular area and four rectangular areas surrounding the rectangular area are logically assumed and processed.

The five rectangular areas shown in FIG. 4 scan image data while sequentially moving. The reference rectangular area is the part where the halftone ratio analysis and the halftone pattern analysis are actually performed, and the four surrounding rectangular areas play an auxiliary role in finding the center in the halftone pattern analysis.

A group of dots may exist only in a blind area because their sizes are all different, but most of them exist over two or more blind areas.

First, the centers of the colored halftone dots and the non-colored halftone dots are found in five rectangular areas. Afterwards, if the group of dots spans another blind area, a correction operation is performed to calculate the center points (X, Y) of the dot pattern in the reference rectangular area using Equations 2 and 3 above.

When the center point is obtained for the halftone dot pattern in this way, the halftone point to be preserved is preserved and the halftone point to be removed is removed by scanning spirally based on the center point of each halftone dot pattern for the CMY image using the information on the obtained center point. do (S603). That is, as shown in FIGS. 5A to 5C , halftone dots for each CMY color image are respectively removed. Here, FIG. 5A is a diagram for explaining a state in which halftone dots are removed from a 1-bit/sample image of color C, and FIG. 5B is a diagram illustrating a state in which halftone dots are removed from a 1-bit/sample image of color M and FIG. 5C is a diagram for explaining a state in which halftone dots are removed from a 1-bit/sample image of Y color.

When the halftone dots are removed for each CMY color image through step S603, the black and white image for the CMY color image as shown in FIG. (S604).

Then, when a black-and-white image from which the halftone dots are removed for the CMY color image is generated through step S604, one black-and-white image for the generated CMY color image and 1 separated in step S601 to express an accurate black color By performing an OR operation on the bit/sample K black-and-white image, a 1-bit/sample black-and-white TIFF image for printing is created (S605).

Even though all the components constituting the embodiment of the present invention described above are described as being combined or operated in combination, the present invention is not necessarily limited to this embodiment. That is, within the scope of the object of the present invention, all of the components may operate by selectively combining one or more. In addition, although all the components may be implemented as one independent hardware, some or all of the components are selectively combined to perform some or all functions combined in one or a plurality of hardware program modules It may be implemented as a computer program having In addition, such a computer program is stored in a computer readable media such as a USB memory, a CD disk, a flash memory, etc., read and executed by a computer, thereby implementing an embodiment of the present invention. The computer program recording medium may include a magnetic recording medium, an optical recording medium, a carrier wave medium, and the like.

As described above, the apparatus and method for generating a black-and-white image by preserving the halftone pattern of the image from the color image separated in the CMYK color space according to the present invention have been described according to embodiments, but the scope of the present invention is limited to specific embodiments It is not limited to, and various alternatives, modifications, and changes can be carried out within the range obvious to those of ordinary skill in the art in relation to the present invention.

Accordingly, the embodiments and the accompanying drawings described in the present invention are for explanation rather than limiting the technical spirit of the present invention, and the scope of the technical spirit of the present invention is not limited by these embodiments and the accompanying drawings. . The protection scope of the present invention should be construed by the claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

100: image separator
200: halftone processing unit
210: halftone ratio analysis and pattern analysis unit
220: halftone dot removal unit
230: black and white image generator
300: arithmetic unit

Claims (16)

In the printing apparatus,
an image separation unit that separates the input CMYK image into a CMY color image and a K black and white image, respectively;
a halftone dot processing unit that analyzes a halftone dot ratio and a halftone dot pattern for each of the separated CMY color images, removes the halftone dots for each CMY color image using the analyzed halftone dot ratio and halftone dot pattern, respectively, and generates a single black-and-white image; and
The black-and-white image is generated by preserving the halftone pattern of the image separated by the CMYK color space, which includes a calculation unit for outputting a black-and-white image for printing by calculating the generated single black-and-white image and the separated K black-and-white image device to do. According to claim 1,
The input CMYK image is a 1-bit/sample TIFF image. An apparatus for generating a black-and-white image by preserving a halftone pattern of an image from a color image separated in a CMYK color space. According to claim 1,
An apparatus for generating a black-and-white image by preserving a halftone dot pattern of an image from a color image separated in a CMYK color space in which the image generated by the halftone processing unit is a 1-bit/sample black-and-white image. According to claim 1,
The halftone dot processing unit,
Analysis and pattern of each halftone dot ratio for each color image of CMY separated through the image separation unit, and halftone dots to be preserved and halftone dots to be removed from each of the CMY images analyzed for each halftone dot pattern, respectively analysis department;
a halftone dot removal unit that maintains the halftone dots to be preserved and removes the halftone dots to be removed from the CMY image extracted through the halftone dot ratio analysis and pattern analysis unit; and
A black-and-white image by preserving the halftone pattern of the image from the color image separated into the CMYK color space, which includes a black-and-white image generator that generates one 1-bit/sample black-and-white image by calculating each CMY image maintained through the halftone dot removal unit. device that generates it. 5. The method of claim 4,
The black-and-white image generation unit generates a black-and-white image by preserving the halftone pattern of the image from the color image separated by the CMYK color space, which generates one 1-bit/sample black-and-white image by ORing each of the CMY images. Device. 5. The method of claim 4,
In the halftone ratio analysis and pattern analysis unit, the halftone ratio analysis is performed by calculating the number of halftone dots having the color of the corresponding color in a reference rectangular area of 16 dots of 1 Byte (8bit) Х vertical 1Byte (8bit), and then using Equation 1 below. A device that generates a black-and-white image by preserving the halftone pattern of an image from a color image separated in the CMYK color space, which is to obtain the number of halftone dots to be preserved by multiplying the brightness ratio as shown.
[Equation 1]
Number of dots to be preserved = number of dots Х ratio of color brightness 7. The method of claim 6,
The pattern analysis of the halftone dots,
After finding the centers of the colored and non-colored halftone dots in the reference rectangular area, correction is performed if the group of halftone dots spans different rectangular areas, and then the center point (X, Y) for the halftone dot pattern in the reference rectangular area. Apparatus for generating a black-and-white image by preserving a halftone pattern of an image from a color image separated in a CMYK color space, which is calculated using Equations 2 and 3 below.
[Equation 2]
X = X - ((8 - LX) / 2) + (RX / 2)
[Equation 3]
Y = Y - ((8 - TY) / 2) + (BY / 2)
where (X, Y) = position of the center point of the reference rectangular area, (TX, TY) = position of the center point of the upper rectangular area, (BX, BY) = position of the center point of the lower rectangular area, (LX, LY) = The position of the center point of the left rectangular area, (RX, RY) = means the position of the center point of the right rectangular area. 8. The method of claim 7,
The halftone dot removing unit,
By preserving the halftone dot pattern of the image from the color image separated by the CMYK color space, which scans in a spiral based on the center point of each halftone pattern for the CMY image and preserves the halftone dots to be preserved and removes the halftone dots to be removed. A device that produces black and white images. A method of generating a black-and-white image by preserving a halftone pattern of an image from a color image separated in a CMYK color space in a printing apparatus, the method comprising:
separating the input CMYK image into a CMY color image and a K black-and-white image;
analyzing a halftone dot ratio and a halftone dot pattern for each of the separated CMY color images, removing the halftone dots for each CMY color image using the analyzed halftone dot ratio and halftone dot pattern, respectively, and then generating one black and white image; and
The black-and-white image is generated by preserving the halftone pattern of the image separated in the CMYK color space, comprising the step of outputting a black-and-white image for printing by calculating the generated single black-and-white image and the separated K black-and-white image How to. 10. The method of claim 9,
The input CMYK image is a 1-bit/sample TIFF image. A method of generating a black-and-white image by preserving a halftone pattern of an image from a color image separated in a CMYK color space. 10. The method of claim 9,
The image generated through the step of generating the black-and-white image is a 1-bit/sample black-and-white image. A method for generating a black-and-white image by preserving a halftone pattern of an image from a color image separated in a CMYK color space. 10. The method of claim 9,
The step of generating the black-and-white image,
extracting each halftone dot ratio for each of the separated CMY color images and a halftone point to be preserved and a halftone point to be removed from each of the CMY images analyzing each halftone dot pattern;
maintaining the halftone dots to be preserved for the extracted CMY image and removing each halftone point to be removed; and
and generating one 1-bit/sample black-and-white image by calculating each of the CMY images maintained above. 13. The method of claim 12,
The step of generating the black-and-white image,
A method of generating a black-and-white image by preserving a halftone pattern of an image from a color image separated in a CMYK color space, which generates one 1-bit/sample black-and-white image by ORing each of the CMY images. 13. The method of claim 12,
In the extracting step, the halftone dot ratio analysis is performed by obtaining the number of halftone dots having the color of the corresponding color in the reference rectangular area of 16 dots of 1 Byte (8bit) Х vertical 1Byte (8bit), and then the brightness ratio as shown in Equation 1 below. A method of generating a black-and-white image by preserving the halftone pattern of an image from a color image separated in the CMYK color space, which is to obtain the number of halftone dots to be preserved by multiplying by
[Equation 1]
Number of dots to be preserved = number of dots Х ratio of color brightness 15. The method of claim 14,
In the extraction step, in the pattern analysis of the halftone dots, after obtaining the centers of the colored and non-colored halftone dots in the reference rectangular area, correction is performed if the halftone dot group spans other rectangular areas, and then the reference rectangular area A method of generating a black-and-white image by preserving the halftone dot pattern of the image from the color image separated in the CMYK color space, which is to calculate the center point (X, Y) for the halftone dot pattern in the following Equations 2 and 3 .
[Equation 2]
X = X - ((8 - LX) / 2) + (RX / 2)
[Equation 3]
Y = Y - ((8 - TY) / 2) + (BY / 2)
where (X, Y) = position of the center point of the reference rectangular area, (TX, TY) = position of the center point of the upper rectangular area, (BX, BY) = position of the center point of the lower rectangular area, (LX, LY) = The position of the center point of the left rectangular area, (RX, RY) = means the position of the center point of the right rectangular area. 16. The method of claim 15,
The step of removing each of the halftone dots is:
By preserving the halftone dot pattern of the image from the color image separated by the CMYK color space, which scans in a spiral based on the center point of each halftone pattern for the CMY image and preserves the halftone dots to be preserved and removes the halftone dots to be removed. How to create a black and white image.

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