JP2004289623A - Dot forming device and dot forming program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dot forming device, a dot forming program and a dot forming matrix in which interference between periodical noises and dots is small and avoidance of graininess in highlight can be realized. <P>SOLUTION: Dots are formed by aggregation of drawing pixels of each of CMYK colors according to the number of gradation values, drawing pixels for a noise of respective colors LC, LM, LY and G which are thinner than each color of the CMYK are dispersed outside the dots. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a network that converts gradation image data representing an image with gradation values into halftone image data representing a halftone image consisting of binary values of an image portion and a non-image portion corresponding to the gradation value. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dot conversion device, a halftone dot conversion program, and a halftone dot matrix that defines halftone dots used in the halftone dot conversion device and the halftone dot conversion program.
[0002]
[Prior art]
In recent years, with the improvement in resolution and image quality of inkjet printers, there has been a demand for outputting halftone images using inkjet printers, for example, for use in proof systems that simulate printing before printing in the printing field. It is growing.
[0003]
A general halftone dot image is composed of halftone dots arranged periodically, and the size of each halftone dot depends on the density of the image. When a printed matter is produced by a printing machine, halftone dot-shaped irregularities are formed on the printing plate, ink adheres to the concave or convex portions of the printing plate, and the ink is transferred onto the printing paper. As a result, a halftone image is formed.
[0004]
On the other hand, an ink jet printer is a device that ejects ink particles that are much finer than a halftone dot and have a uniform size onto a sheet of paper, hits ink dots, and outputs an image based on the set of ink dots. An image is output by hitting ink dots at a density corresponding to the density. When a halftone dot image is output by such an ink jet printer, a halftone dot shape having a size corresponding to the density of the image is reproduced by a set of ink dots. However, when a halftone image is output using an ink jet printer, various periodic noises are often generated in the output image due to a paper feed error or an ink ejection position error in the ink jet printer. There is a strong possibility that typical noise interferes with the periodic structure of halftone dots and causes image quality degradation such as unevenness.
[0005]
In order to avoid such image quality degradation, periodic noise and the periodic structure of halftone dots are obtained by scattering ink dots between the halftone dots drawn with ink dots, where ink dots are not originally attached. A technique for reducing the interference is proposed (for example, see Patent Document 1).
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-144959
[Problems to be solved by the invention]
However, the technique proposed in Patent Document 1 is rough when the highlight portion of the output image is generated with ink dots based on, for example, FM halftone processing or error diffusion method. There is an inconvenience that a so-called rough image is produced. Such inconvenience is currently regarded as a problem in ink jet printers, but does not necessarily occur only in ink jet printers, and may generally occur when a halftone dot structure is reproduced with fine dots. There is some inconvenience.
[0008]
In view of the above circumstances, the present invention can create a halftone image in which interference between the periodic noise and the halftone dot structure is small even when periodic noise occurs during output. It is an object of the present invention to provide a halftoning apparatus, a halftoning program, and a halftone matrix capable of easily creating such a halftone image in which highlighting is avoided.
[0009]
[Means for Solving the Problems]
The halftone dot image forming apparatus of the present invention that achieves the above object converts gradation image data representing an image with gradation values into halftone image data representing an image with halftone dots having a size corresponding to the gradation value. In the halftone dot conversion device,
A gradation value acquisition unit for obtaining gradation values of gradation image data;
A halftone dot is formed by a set of first drawing elements corresponding to the gradation value obtained by the gradation value acquisition unit, and has a lighter color than the first drawing element outside the halftone dot. And a halftoning unit for interspersing the second drawing elements.
[0010]
According to the halftone dot conversion apparatus of the present invention, a halftone dot image is formed with halftone dots having a size corresponding to the gradation value, and second drawing elements are scattered between the halftone dots. As a result, the contrast between the halftone dots and the surrounding area is reduced. Therefore, even when periodic noise is generated when a halftone image is output by an ink jet printer or the like, the periodic noise and the halftone are reduced. Interference with the periodic structure of points is small. Further, since the color of the second drawing element is lighter than the color of the first drawing element forming a halftone dot, it is not noticeable, and overall roughness can be suppressed.
[0011]
Here, it is preferable that the halftone forming unit in the halftone forming apparatus according to the present invention is configured to disperse the second drawing elements outside the halftone dots for the gradation values excluding the predetermined range in the highlight.
[0012]
If the second drawing element is scattered outside the halftone dot in the highlight having a low density, the roughness is particularly easily recognized. Therefore, it is preferable that the second drawing elements are scattered only for the gradation values excluding the predetermined area in the highlight.
[0013]
Here, it is preferable that the halftone forming unit in the halftone forming apparatus of the present invention increases or decreases the number of second drawing elements scattered outside the halftone dot in accordance with the gradation value.
[0014]
Image quality can be improved by increasing or decreasing the number of second drawing elements scattered outside the halftone dot according to the gradation value.
[0015]
In the halftoning device of the present invention, the gradation image data represents an image with gradation values representing a dot% density of 0% to 100%,
It is preferable that the halftone dot conversion unit uses a range in which the lower limit value of the gradation value is 0% and the upper limit value is a value between 5% and 15% as the predetermined range.
[0016]
If it is said range, interference irregularity can fully be made inconspicuous, suppressing the roughness in highlight.
[0017]
Further, in the halftoning device of the present invention, the gradation image data represents images of four colors of cyan, magenta, yellow, and black,
The halftone dot conversion unit may disperse the second drawing elements outside the halftone dot only when the color of the image is black.
[0018]
Further, in the halftoning device of the present invention, the gradation image data represents images of four colors of cyan, magenta, yellow, and black,
The halftone dot conversion unit may disperse the second drawing elements outside the halftone dot only when the color of the image is a color other than yellow.
[0019]
Since black is dark in color, it is easy to recognize the interference between periodic noise and halftone dot structure due to the output device such as the above-mentioned ink jet printer. On the contrary, since yellow is light in color, the interference is recognized. It is hard to be done.
[0020]
Further, the halftone dot program according to the present invention for achieving the above object is the halftone dot image data in which an image is represented by a halftone dot having a size corresponding to the gradation value. In a halftoning program that converts to
A gradation value acquisition unit for obtaining gradation values of gradation image data;
A halftone dot is formed by a set of first drawing elements corresponding to the gradation value obtained by the gradation value acquisition unit, and a lighter color than the color of the first drawing element is formed outside the halftone dot. And a halftone dot unit for dispersing the second drawing elements.
[0021]
It should be noted that the halftone dot program referred to in the present invention is only shown in its basic form here, but this is only for avoiding duplication, and the halftone dot program referred to in the present invention includes the above basic program. Not only the form but also various forms corresponding to each form of the halftone dot forming apparatus described above are included.
[0022]
Further, in the halftone dot conversion apparatus of the present invention and the halftone dot conversion program, the same names such as the gradation value acquisition unit are given as the component names constituting them. In the case of a program, it refers to software that performs such an action, and in the case of a halftone dot device, it refers to that including hardware.
[0023]
Furthermore, the constituent elements such as the gradation value acquisition unit constituting the halftone dot program of the present invention may be one in which the function of one constituent element is carried by one program component. May be carried by a plurality of program parts, or the functions of a plurality of components may be carried by a single program part. In addition, these components may execute such actions themselves, or may be executed by giving instructions to other programs and program components incorporated in the computer. Also good.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0025]
FIG. 1 is a perspective view showing a printing system and a proof system configured to incorporate an embodiment of the present invention.
[0026]
In this perspective view, a proof system 10 constituted by a computer system 100 and a large inkjet printer 200, and a printing system 20 including a computer system 400, a CTP 500, and a printing machine not shown are shown. The two computer systems 100 and 400 are connected to each other via a communication network 300, and the communication network 300 is also connected to an external computer system (not shown) other than the computer systems 100 and 400.
[0027]
In the computer system 400 of the printing system 20 shown in FIG. 1, image data representing an edited printed page is input from an external computer system via the communication network 300. As an example of the image data, here, C, M, Y, and K halftone dot data representing an image with a set of pixels having any halftone value from 0% to 100% is used. . The halftone value corresponds to an example of the gradation value referred to in the present invention, but the pixel here has a different concept from the drawing element referred to in the present invention. The network% data of each version may be input via a storage medium such as a CD-R (Compact Disc Recordable) or an MO (magneto-optical disk) in addition to the communication network 300 as described above. The halftone data input to the computer system 400 is subjected to halftone dot processing by the computer system 400, and is used for printing that represents a halftone dot image composed of halftone dots having a size corresponding to the halftone value. Halftone data is generated.
[0028]
The halftone dot data for printing generated by the computer system 400 is passed to the CTP 500, and a printing plate is created by directly printing the halftone dot image represented by the halftone dot data thus passed. . When the printing press has, for example, a drum, the printing plate created by the CTP 500 is wound around the drum, and the printing press on the printing plate on the drum places ink on the printing plate so that a continuous dot image is formed. Printing is performed. In addition, the printing plate may be created based on a film formed by forming an image represented by the halftone dot data on a film by a so-called film setter.
[0029]
In this way, a series of printing operations by the printing system 20 becomes large and costly. For this reason, the print operator creates a proof image in the following manner by the proof system 10 before performing an actual printing operation, and refers to the proof image, thereby printing an image printed by the printing system 20. The advance check of the finish of is performed.
[0030]
Similarly to the computer system 400, the computer system 100 of the proof system 10 is input to the computer system 400 through the communication network 300 or a storage medium such as a CD-R or MO. The same halftone data for each color of CMYK is input. The computer system 100 functions as a halftone dot conversion apparatus according to the present embodiment, and the computer system 100 converts the halftone data input into proof halftone dot data. The converted proof dot data is output to the large-scale inkjet printer 200. Here, in the present embodiment, the large-sized inkjet printer 200 includes light cyan (LC), light magenta (LM), light magenta (LM), and light inks that are lighter in color than cyan, magenta, yellow, and black dark ink. It is possible to use eight color inks including light yellow (LY) and four light inks of gray (G). The large inkjet printer 200 receives halftone dot data for proofing, and prints out a proof image on a recording sheet based on the received halftone dot data. The proof image output in this way is an image obtained by reproducing not only the color but also the halftone dot pattern of the image printed by the printer.
[0031]
The proof image is not necessarily output only on the recording paper, and may be output on the display of the computer system 100, for example. When the proof image is output on the display in this way, the computer system 100 functions as a proof system alone. However, although the form in which the proof image is output on the display is also one form of the halftone dot forming apparatus of the present invention, this form is different from the desirable form in which the operational effect of the present invention is particularly effective. The description will be continued on the assumption that a proof image is output by the large-sized inkjet printer 200.
[0032]
Note that these computer systems 100 and 400 express page description data in which a page is described as an arrangement of objects such as images, characters, and illustrations in a postscript language or the like as a set of pixels like the above-described network% data. When the image data input to the computer systems 100 and 400 is provided with a RIP (Raster Image Processor) for converting the data into the bitmap data, the page description data is used instead of the network% data. May be used. When the same page description data is input to the computer systems 100 and 400, the same network% data is generated in the computer systems 100 and 400, and each of these network% data is a halftone dot for each. Converted to data.
[0033]
A feature of the computer system 100 shown in FIG. 1 as an embodiment of the present invention resides in processing contents executed inside the computer system 100 when functioning as a halftone dot conversion device. The computer system 100 will be described in detail below. To do. The computer system 400 used in the printing system 20 has the same configuration as the computer system 100 used in the proof system 10 in terms of hardware.
[0034]
The computer system 100 includes a main body 101 incorporating a CPU, a main storage device, a hard disk, a communication board, and the like, a CRT display 102 that displays a screen and a character string on a display screen 102a according to an instruction from the main body 101, By specifying an arbitrary position on the display screen 102a, a keyboard 103 for inputting user instructions and character information to the computer system 100, an instruction corresponding to an icon or the like displayed at that position is input. A mouse 104 is provided.
[0035]
The hardware configuration of the computer system 100 is as follows.
[0036]
FIG. 2 is a hardware configuration diagram of the computer system.
[0037]
In this hardware configuration diagram, a CPU (Central Processing Unit) 111, a RAM 112, an HDD (Hard Disk Drive) 113, an MO drive 114, a CD-ROM drive 115, and a communication board 116 are shown. 110 are mutually connected.
[0038]
The HDD 113 has a built-in hard disk 120 as a recording medium, and records and reproduces information on the hard disk 120.
[0039]
The communication board 116 is connected to a communication line such as a LAN. The computer system 100 shown in FIG. 1 can transmit and receive data to and from other computer systems such as the computer system 400 through the communication network 300 connected via the communication board 116.
[0040]
Also shown are a mouse 104, a keyboard 103, a CRT display 102, and a large inkjet printer 200 connected to the bus 110 via a plurality of I / O interfaces (not shown). In the computer system 400 shown in FIG. 1, a CTP 500 is connected to the bus 110 via an I / O interface (not shown) instead of the large inkjet printer 200.
[0041]
In this embodiment, one embodiment of the halftone dot program of the present invention is stored in the CD-ROM 105.
[0042]
FIG. 3 is a diagram showing an embodiment of the halftoning program of the present invention.
[0043]
As described above, in this embodiment, the halftone dot program 600 is stored in the CD-ROM 105. Here, the CD-ROM 105 is merely an example of a storage medium for storing the halftone dot program 600, and the halftone dot program of the present invention includes a hard disk (HD), a flexible disk (FD), and a magneto-optical (MO). You may memorize | store in other storage media, such as a disk and DVD.
[0044]
When the halftone dot conversion program 600 shown in FIG. 3 is executed in the computer system 100 shown in FIG. 1, the computer system 100 is operated as a halftone dot generation device that generates halftone dot data from halftone data. And is composed of a halftone value acquisition unit 610 and a halftone dot conversion unit 620. The halftone dot conversion unit 620 includes an AM halftone processing unit 621 and an FM halftone processing unit 622. The halftone value acquisition unit 610 and the halftone dot conversion unit 620 correspond to examples of the gradation value acquisition unit and the halftone dot conversion unit in the halftone conversion program of the present invention, respectively.
[0045]
The operation of each element of the halftone dot program 600 will be described later.
[0046]
FIG. 4 is a functional block diagram showing an embodiment of the halftone dot conversion apparatus of the present invention.
[0047]
The halftone dot conversion apparatus 700 shown in FIG. 4 is configured by installing and executing the halftone dot conversion program 600 shown in FIG. 3 in the computer system 100 shown in FIG. Section 710, AM halftone processing section 721, and FM halftone processing section 722. The halftone value acquisition unit 710, the AM halftone processing unit 721, and the FM halftone processing unit 722 include the halftone value acquisition unit 610, the AM halftone processing unit 621, and the halftone conversion program 600 illustrated in FIG. 4 corresponds to the FM halftone processing unit 622, but each element in FIG. 4 is configured by a combination of the hardware of the computer system 100 shown in FIG. 1 and an OS or application program executed on the personal computer. On the other hand, each element of the halftone dot program shown in FIG. 3 is different in that it is composed only of the application program.
[0048]
The halftone value acquisition unit 710 of the halftone dot conversion apparatus 700 corresponds to an example of a gradation value acquisition unit in the halftone dot conversion apparatus of the present invention, and the AM halftone processing unit 721 and the FM halftone processing unit 722 are combined. The thing corresponds to an example of a halftoning unit in the halftoning apparatus of the present invention.
[0049]
Hereinafter, by describing each element of the halftone dot conversion apparatus 700 shown in FIG. 4, each element of the halftone dot conversion program 600 shown in FIG. 3 will also be described.
[0050]
The halftone value acquisition unit 710 constituting the halftoning apparatus 700 in FIG. 4 acquires halftone data 800 for each color of CMYK via the communication network 300 shown in FIG. In addition, the AM halftone processing unit 721 and the FM halftone processing unit 722 create halftone dot data by performing a halftoning process on the halftone data 800 acquired by the halftone value acquisition unit 710. The halftone dot image represented by the halftone dot data is composed of a so-called halftone dot image portion having a collective shape and small image portions scattered outside the halftone dot. The AM halftone processing unit 721 generates halftone dot data (AM binary data 810 in FIG. 4) representing halftone dot image portions of the halftone dot data, and the FM halftone processing unit 722 generates halftone dot data among the halftone dot data. Halftone dot data (FM binary data 820 in FIG. 4) representing small image portions scattered outside the point is generated. These halftone dot data are output to an output device such as the large-sized inkjet printer 200 shown in FIG. In the large inkjet printer 200, the halftone dot image portion is formed of CMYK dark ink, and the small image portions scattered outside the halftone dot are lighter than LC, LM, LY, and G colors having colors lighter than the respective colors of CMYK. A halftone dot image formed of ink is generated.
[0051]
The halftoning device 700 is basically configured as described above.
[0052]
Next, the halftone processing performed by the AM halftone processing unit 721 and the FM halftone processing unit 722 will be described in detail.
[0053]
FIG. 5 is a diagram illustrating an example of a halftone dot matrix used in the AM halftone processing unit.
[0054]
The halftone dot matrix 651 shown in FIG. 5 defines halftone dots, and the halftone dots have a size corresponding to the halftone value. The halftone dot matrix 651 has threshold values 651a to be compared with halftone values arranged in 10 rows × 10 columns, and each threshold value 651a outputs an image by a set of a large number of output points such as ink dots. 1 corresponds to each output point in the output device (here, the large-scale inkjet printer 200 shown in FIG. 1).
[0055]
In the AM halftone processing unit 721 shown in FIG. 4, one halftone value applied to the whole halftone dot matrix 651 is obtained based on the halftone value represented by the halftone data 800, and the value of each threshold 651a is obtained. To be compared. When the halftone value is larger than the threshold value 651a, the position corresponding to the threshold value 651a is set as an output point at which ink or the like is applied by the output device. Since an output point on which ink or the like is applied in this way corresponds to an example of a drawing element according to the present invention, such an output point is hereinafter referred to as a drawing element. A halftone dot is formed by the set of drawing elements. A halftone dot matrix 651 shown in FIG. 5 represents a set of drawing elements that increase in size as the halftone value increases, and defines typical halftone dots that are conventionally known.
[0056]
FIG. 6 is a diagram illustrating a state in which a set of drawing elements grows as the halftone value increases.
[0057]
FIG. 6 shows nine halftone dot matrices 651 that are also shown in FIG. Each halftone dot matrix 651 corresponds to a halftone value of 10% in the upper left corner, 20% in the upper middle, 30% in the upper right edge, 40% in the middle left edge,..., 90% in the lower right edge. As shown in FIG. An area 651b indicated by diagonal lines in each halftone dot matrix 651 represents a set of drawing elements, that is, this area 651b represents a halftone dot shape.
[0058]
A region 651b corresponding to a halftone value of 10% represents a set of ten drawing elements. Similarly, each region 651b corresponding to each halftone value of 20%,. ... represents a set of 90 drawing elements. A drawing element that forms a halftone dot shape among the drawing elements is hereinafter referred to as a halftone dot drawing element. As will be described later, the halftone dot drawing element is formed with dark inks of CMYK colors in the output device, and this halftone dot drawing element corresponds to an example of the first drawing element according to the present invention. .
[0059]
In the AM halftone processing unit 721 shown in FIG. 4, AM binary data 810 representing halftone dots formed by a set of halftone dot drawing elements is generated by the processing as described above. The AM binary data 810 is shown in FIG. 1 is sent to an output device such as the large-scale inkjet printer 200 shown in FIG.
[0060]
Here, in the halftone dot matrix 651 shown here, only the inside of the halftone dot formed by the region 651b is filled. However, the FM halftone processing unit 722 shown in FIG. The drawing elements for noise, which are the drawing elements, are scattered. In order to disperse the noise drawing elements, a noise matrix representing the arrangement configuration of the noise drawing elements is required, and as this noise matrix, as a technique for outputting a continuous tone image with an inkjet printer or the like A conventionally known FM halftone dot matrix using the so-called FM halftone dot technique is applied. This FM halftone technique is a technique in which drawing elements are laid out at a density corresponding to the gradation value so that the mutual interval between the drawing elements is as wide as possible. In order to distinguish between this FM halftone dot and a normal halftone dot as illustrated in FIG. 6, the normal halftone dot may be expressed as an AM halftone dot below.
[0061]
FIG. 7 is a diagram illustrating an example of an FM halftone matrix in which FM halftone dots are defined.
[0062]
Similar to the halftone dot matrix 651 of the AM halftone dot shown in FIG. 5, the FM halftone dot matrix 652 shown here has thresholds 652a to be compared with halftone values arranged in 10 rows × 10 columns. The FM halftone matrix 652 defines FM halftone dots in a state where drawing elements are scattered.
[0063]
FIG. 8 is a diagram showing an FM halftone matrix obtained by improving the FM halftone matrix shown in FIG.
[0064]
The FM halftone matrix 652 shown in FIG. 7 is composed of threshold values 652a from a value “0” to a value “99”, whereas the FM halftone matrix 653 shown here has a value “10” to a value “ The threshold value 653a is up to “99” (partially overlapped).
[0065]
FIG. 9 is a diagram showing a state in which the FM halftone drawing elements defined by the FM halftone matrix shown in FIG. 8 increase as the halftone value increases.
[0066]
9 shows nine FM halftone matrixes 653 that are also shown in FIG. 8, and each FM halftone matrix 653 has halftone values of 10%, 20%,..., 90%. It corresponds to. A region 653b indicated by diagonal lines in each FM halftone matrix 653 represents a position where a drawing element is to be applied.
[0067]
As shown in FIG. 9, the region 653b where the drawing element is applied does not exist with respect to the 10% halftone value, and increases as the halftone value increases. To go. The range of tone values from which 0% to 10% of drawing elements are not applied represents a highlight area with low density (hereinafter, the range of gradation values to which no drawing elements are applied is referred to as a highlight range). ), This highlight range is an example of the predetermined range referred to in the present invention. In the following, this FM halftone matrix 653 is used as a noise matrix, and noise drawing elements are scattered outside the AM halftone dots in accordance with the FM halftone matrix 653. As will be described later, the noise drawing element is formed with light inks of LC, LM, LY, and G colors that are thinner than the CMYK colors in the output device, and this noise drawing element is referred to in the present invention. This corresponds to an example of two drawing elements. Here, in this FM halftone matrix 653, the fact that the drawing elements are not scattered in the highlight range means that when the halftone value represents a light color with a high density on the highlight side, the drawing elements for noise are not. It means not hit.
[0068]
The FM halftone processing unit 722 shown in FIG. 4 uses the FM halftone matrix 653 to perform the same processing as when the AM binary data 810 is created by the AM halftone processing unit 721, and the noise drawing element performs the processing. FM binary data 820 representing the FM halftone dot to be formed is generated. The FM binary data 820 is sent to an output device such as the large-scale inkjet printer 200 shown in FIG.
[0069]
FIG. 10 is a diagram illustrating a result of outputting AM halftone dots represented by AM binary data and FM halftone dots represented by FM binary data.
[0070]
FIG. 10 shows an AM halftone dot indicated by a region 651b in each halftone dot matrix 651 in FIG. 6 corresponding to each halftone value of 10%, 20%,. Nine halftone dot portions 850_1 for one pixel when the FM halftone dot indicated by the region 653b in the dot matrix 653 is output are shown side by side.
[0071]
An image portion 850_1a indicated by hatching in each halftone portion 850_1 corresponds to a region 651b of each halftone matrix 651 in FIG. 6, and an AM halftone dot is formed by a halftone dot drawing element. Further, an image portion 850_1b indicated by a cross in each halftone portion 850_1 corresponds to a region 653b of each halftone matrix 653 in FIG. 9, and FM halftone dots are formed by noise drawing elements.
[0072]
When the AM binary data 810 is sent from the AM halftone processing unit 721 shown in FIG. 4 and the FM binary data 820 is sent from the FM halftone processing unit 722, the large-scale inkjet printer 200 shown in FIG. The image portion 850_1a of the halftone dot portion 850_1 is output using dark ink of each color of CMYK to form a dark ink image 830. Further, by outputting the image portion 850_1b using light inks of LC, LM, LY, and G colors corresponding to CMYK colors, a light ink image 840 is formed, and a dark ink image 830 and a light ink image are formed. A halftone dot image 850 in which 840 is superimposed is generated. Therefore, according to the halftone dot conversion apparatus 700 of the present embodiment, even when periodic noise occurs during output, interference between the periodic noise and the halftone dot periodic structure can be suppressed. Furthermore, the overall roughness can be avoided by forming the noise drawing element with light ink having a light color.
[0073]
Here, in the halftone dot portion 850_1 in FIG. 10, as the halftone value increases to 10%, 20%,..., 90%, the number of halftone dot drawing elements increases, and the image portion 850_1a becomes larger in a lump. Furthermore, the number of noise drawing elements is increased, and the image portion 850_1b is scattered outside the image portion 850_1a. However, this noise drawing element is not shown in the halftone dot portion 850_1 at the upper left end of the highlight range (halftone value is 0% to 10%). Since the drawing element for noise is formed by light ink, the roughness is originally avoided. However, according to the halftone dot forming apparatus 700 of the present embodiment, the roughness is further suppressed when the density on the highlight side is light. be able to.
[0074]
In the above, description has been made with reference to FIGS. 5 to 10 showing one AM halftone dot and noise drawing elements scattered outside the AM halftone dot. Here, the AM halftone dot and the noise drawing element are formed. The halftone image to be performed will be described.
[0075]
FIG. 11 is a diagram illustrating an example of an image for dark ink. The dark ink image 830 also shown in FIG. 4 represents an image constituted by AM halftone dots arranged periodically.
[0076]
FIG. 12 is a diagram illustrating an example of a light ink image. The light ink image 840 also shown in FIG. 4 represents an image of FM halftone dots arranged irregularly.
[0077]
FIG. 13 is a diagram illustrating an example of a halftone image. The halftone dot image 850 also shown in FIG. 4 represents an image in which light ink images 840 that are noise drawing elements are scattered around the dark ink image 830 constituting the halftone dots. The dark ink image 830 is output with dark inks of CMYK colors by an output device such as the large-scale inkjet printer 200 of FIG. 1, and the light ink image 840 is a light of LC, LM, LY, G colors corresponding to the CMYK colors. A halftone image 850 is generated by being output with ink so as to be superimposed on the dark ink image 830.
[0078]
The description so far is focused on one of the four colors of CMYK, and the halftone dot processing as described above may be performed on the halftone data of each color of CMYK, as described below. Depending on the color, halftone processing may be used properly.
[0079]
FIG. 14 is a diagram for explaining how to use halftone processing according to color.
[0080]
Here, instead of the AM halftone processing unit 721 and the FM halftone processing unit 722 shown in FIG. 4, an AM halftone processing unit 721 ′ and an FM halftone processing unit 722 ′ that perform different use are used. To do.
[0081]
The AM halftone processing unit 721 ′ and the FM halftone processing unit 722 ′ receive halftone data 800_1, 800_2, 800_3, and 800_4 for each color of CMYK, and are subjected to a halftoning process. Here, the halftone data 800_1, 800_2, and 800_3 of the CMK three colors among the four colors of CMYK are subjected to a halftoning process in the AM halftone processing unit 721 ′ and the FM halftone processing unit 722 ′. The halftone data 800_4 of Y color among the CMYK4 colors is not subjected to the halftone processing by the FM halftone processing unit 722 ′, but only the halftone processing by the AM halftone processing unit 721 ′. Is done.
[0082]
As a result of such use of the halftone processing performed by the AM halftone processing unit 721 ′ and the FM halftone processing unit 722 ′, as for CMK3 colors, AM binary data (810_1, 810_2, 810_3) representing the AM halftone is used. ) And FM binary data (820_1, 820_2, 820_3) representing noise drawing elements scattered outside the AM halftone dot, and only AM binary data (810_4) representing the AM halftone dot is obtained for the Y color. .
[0083]
Since the density of the Y color is lower than the density of the three CMK colors, the interference between the periodic noise generated in an ink jet printer or the like and the halftone dot structure is unlikely to occur in the Y color, and the AM halftone dot that is originally intended to be reproduced is used as it is in the Y color. Therefore, it is desirable to properly use as described above.
[0084]
Next, a modified example of proper use of halftone processing will be described.
[0085]
FIG. 15 is a diagram for explaining a modified example of proper use of the halftone processing.
[0086]
Here, instead of the AM halftone processing unit 721 ′ and the FM halftone processing unit 722 ′ shown in FIG. 14, an AM halftone processing unit 721 ″ and an FM halftone processing unit 722 ″ that perform different use are used. Shall be used. The AM halftone processing unit 721 ″ and the FM halftone processing unit 722 ″ also receive halftone data 800_1, 800_2, 800_3, and 800_4 of each color of CMYK, and are each subjected to a halftoning process. Here, halftone data 800_1 for K color among CMYK4 colors is subjected to halftoning processing in AM halftone processing unit 721 ″ and FM halftone processing unit 722 ″. Of these, the halftone data 800_2, 800_3, and 800_4 of the CMY three colors are not subjected to the halftoning process by the FM halftone processing unit 722 ″, and the halftone processing by the AM halftone processing unit 721 ″ is performed. Only processing is applied.
[0087]
As a result of the use of halftone processing in the AM halftone processing unit 721 ″ and the FM halftone processing unit 722 ″, AM binary data 810_1 and FM binary data 820_1 are obtained for the K color. , AM binary data 810_2, 810_3, and 810_4 are obtained for three colors of CMY.
[0088]
Since the density of the K color is higher than the density of the CMY three colors, the interference between the periodic noise generated in an ink jet printer or the like and the halftone dot structure occurs remarkably in the K color. Therefore, it is desirable to use only halftone dots for the K colors of the four CMYK colors, using halftone dots with scattered noise halftone dots, and using halftone dots for the CMY3 colors to use AM halftone dots that are originally intended to be reproduced. .
[0089]
The description of the first embodiment has been completed, and a second embodiment different from the first embodiment will be described. The halftoning apparatus of the present embodiment has the same components as the halftoning apparatus 700 shown in FIG. 4, but the processes performed in the AM halftone processing unit and the FM halftone processing unit are different. Only the differences from the first embodiment will be described below.
[0090]
FIG. 16 is a functional block diagram showing a second embodiment of the halftone dot conversion apparatus of the present invention.
[0091]
The halftone dot conversion apparatus 701 shown in FIG. 16 includes a halftone value acquisition unit 710, an AM halftone processing unit 731 and an FM halftone processing unit 732. The halftone processing unit 701 shown in FIG. Only the operations of the AM halftone processing unit 731 and the FM halftone processing unit 732 are different from the dot conversion device 700.
[0092]
The halftone value acquisition unit 710 obtains halftone data 800 for each color of CMYK via the communication network 300 shown in FIG. The halftone data 800 is sent to both the AM halftone processing unit 731 and the FM halftone processing unit 732.
[0093]
The AM halftone processing unit 731 generates AM binary data 810 representing a halftone dot on the basis of the halftone data 800 sent from the halftone value obtaining unit 710 by the same processing as in the first embodiment. The generated AM binary data 810 is sent to an output device such as the large-sized inkjet printer 200 of FIG. 1, and is also sent to the FM halftone processing unit 732, unlike the first embodiment.
[0094]
First, the FM halftone processing unit 732 also performs FM binary data 820 (representing noise drawing elements) by the same processing as in the first embodiment based on the halftone data 800 sent from the halftone value obtaining unit 710. (See FIG. 4).
[0095]
Here, the FM binary data 820 generated by the FM halftone processing unit 732 is sent to the output device as it is, and halftone dots and noise drawing elements based on the AM binary data 810 and the FM binary data 820 are formed on the recording paper. Then, in the image portion where the halftone dot and the noise drawing element overlap, a lot of ink is overlaid. When a large amount of ink is overlaid on the recording paper, the amount of ink will cause the ink to overflow and flow out on the recording paper, or the recording paper will absorb and absorb a large amount of ink, or the ink will dry. There is a risk that defects such as cracks in the film or peeling of the film that causes ink to peel off may occur. In order to solve this problem, the FM halftone processing unit 732 according to the present embodiment performs processing for omitting the noise drawing elements in the image portion where the halftone dots and the noise drawing elements overlap.
[0096]
The FM halftone processing unit 732 thins out the image portion overlapping with the AM binary data 810 sent from the AM halftone processing unit 731 from the generated FM binary data 820, and generates corrected FM binary data 821. The generated corrected FM binary data 821 is sent to an output device such as the large-scale inkjet printer 200 of FIG.
[0097]
In the large-scale inkjet printer 200, the dark ink image 830 based on the AM binary data 810 is output using the CMYK color dark inks, and the corrected light ink image 841 based on the corrected FM binary data 821 is LC, LM, LY. , G output using each light ink to create a halftone image 851. The halftone dot image 851 is an image in which the dark ink image 830 and the light ink image 840 of the halftone dot image 850 shown in FIG. 13 overlap with each other so that the light ink is omitted. Is the same as the halftone image 850 of FIGS. As described above, in the image portion where the halftone dot and the noise drawing element overlap, it is possible to prevent problems such as film peeling by omitting the noise drawing element. The use of can be suppressed.
[0098]
This is the end of the description of each embodiment.
[0099]
In the above description, an example of a halftoning device connected to a large inkjet printer is shown. However, the halftoning device of the present invention is not necessarily required to be connected to an inkjet printer. Instead, it may be an apparatus independent of the printer, or may be connected to a printer other than the ink jet printer.
[0100]
Further, in the above description, an example of a halftone dot conversion unit has been described in which noise drawing elements are scattered outside the halftone dots based on FM halftone dots in which the drawing elements increase or decrease according to the gradation value. For example, the halftone dot conversion unit may disperse a fixed number of noise drawing elements outside the halftone dot regardless of the gradation value.
[0101]
In the above description, a halftone dot matrix in which the shape of one halftone dot is defined is shown as an embodiment of the halftone dot matrix of the present invention. However, the halftone dot matrix of the present invention is composed of a plurality of halftone dots. The halftone dot group shape may be defined.
[0102]
【The invention's effect】
As described above, according to the halftone dot conversion apparatus, halftone dot conversion program, and halftone dot matrix storage medium of the present invention, the interference between the periodic noise and the halftone dot periodic structure is small, and the roughness in the highlight is avoided. Is also realized.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a printing system and a proof system configured to incorporate an embodiment of the present invention.
FIG. 2 is a hardware configuration diagram of a computer system.
FIG. 3 is a diagram showing an embodiment of a halftoning program of the present invention.
FIG. 4 is a functional block diagram showing an embodiment of the halftone dot conversion apparatus of the present invention.
FIG. 5 is a diagram illustrating an example of a halftone dot matrix used in an AM halftone processing unit.
FIG. 6 is a diagram showing a state in which a set of drawing elements grows as the halftone value increases.
FIG. 7 is a diagram illustrating an example of an FM halftone matrix in which FM halftone dots are defined.
FIG. 8 shows an improved FM halftone matrix.
FIG. 9 is a diagram illustrating a state in which the FM halftone drawing elements defined by the FM halftone matrix shown in FIG. 8 increase as the halftone value increases.
FIG. 10 is a diagram illustrating a result of outputting an AM halftone dot represented by AM binary data and an FM halftone dot represented by FM binary data.
FIG. 11 is a diagram illustrating an example of an image for dark ink.
FIG. 12 is a diagram illustrating an example of an image for light ink.
FIG. 13 is a diagram illustrating an example of a halftone image.
FIG. 14 is a diagram for explaining how to use halftone processing according to color.
FIG. 15 is a diagram illustrating a modified example of proper use of halftone processing.
FIG. 16 is a functional block diagram showing a second embodiment of the halftoning device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Proof system 20 Printing system 100 Computer system 101 Main body part 102a Display screen 102 CRT display 103 Keyboard 104 Mouse 105 CD-ROM
106 MO
110 Bus 111 CPU (Central processing unit)
112 RAM
113 HDD (Hard Disk Drive)
114 MO drive 115 CD-ROM drive 116 Communication board 120 Magnetic disk 200 Large inkjet printer 300 Communication network 400 Computer system 500 CTP
600 halftone conversion program 610 halftone value acquisition unit 620 halftone conversion unit 621 AM halftone processing unit 622 FM halftone processing unit 700 halftone conversion device 710 halftone value acquisition unit 721 AM halftone processing unit 722 FM halftone processing Part 800 halftone data 800_1,..., 800_4 halftone data 810, 810_1,..., 810_4, 820_1,...

Claims (7)

In a halftone dot conversion device for converting gradation image data representing an image with gradation values into halftone dot image data representing an image with halftone dots having a size corresponding to the gradation value,
A gradation value acquisition unit for obtaining a gradation value of the gradation image data;
The halftone dot is formed by a set of first drawing elements corresponding to the gradation value obtained by the gradation value acquisition unit, and the color of the first drawing element is outside the halftone dot. A halftoning apparatus comprising: a halftoning unit for interspersing second drawing elements having a light color. 2. The halftone dot according to claim 1, wherein the halftone dot conversion unit is configured to disperse the second drawing element outside the halftone dot for a gradation value excluding a predetermined range in highlight. Device. The gradation image data represents an image with a gradation value representing a halftone density of 0% to 100%,
The halftone dot conversion unit uses, as the predetermined range, a range in which a lower limit value of a gradation value is 0% and an upper limit value is a value between 5% and 15%. The halftone dot conversion apparatus according to claim 2. The halftone dot conversion apparatus according to claim 1, wherein the halftone dot conversion unit increases or decreases the number of second drawing elements scattered outside the halftone dot in accordance with a gradation value. The gradation image data represents images of four colors of cyan, magenta, yellow, and black,
2. The halftone dot conversion according to claim 1, wherein the halftone dot forming unit is to disperse the second drawing element outside the halftone dot only when the color of the image is the black. apparatus. The gradation image data represents images of four colors of cyan, magenta, yellow, and black,
2. The halftone dot conversion unit is characterized in that the second drawing element is scattered outside the halftone dot only when the color of the image is a color other than the yellow color. The halftone dot converting apparatus. In a halftone dot conversion program for converting gradation image data expressing an image with gradation values into halftone dot image data expressing an image with halftone dots of a size corresponding to the gradation value,
A gradation value acquisition unit for obtaining a gradation value of the gradation image data;
The halftone dot is formed by a set of first drawing elements corresponding to the gradation value obtained by the gradation value acquisition unit, and the color of the first drawing element is outside the halftone dot. A halftone dot conversion program comprising: a halftone dot conversion unit for interspersing second drawing elements having a light color.

Images