JP2019010849A - Image processing device, printer, image processing method, and image processing program - Google Patents

Abstract

To provide a printer capable of performing printing in which deterioration of printing quality is suppressed even when performing edge processing of an image in the printer using action liquid such as white ink and clear ink as a ground layer.SOLUTION: An image processing device generating print data causing a printer to execute printing on the basis of image data, comprises: a dot formation specification determination part determining dot formation specifications on the basis of the image data; and a print data generation part generating the print data on the basis of the dot formation specifications. The dot formation specification determination part independently performs edge processing to a contour pixel region of a partial image of color ink and edge processing to a contour pixel region of partial image of white ink (action liquid).SELECTED DRAWING: Figure 16

Description

  The present invention relates to an image processing apparatus, a printing apparatus including the image processing apparatus, an image processing method, and an image processing program that executes processing according to the image processing method.

Conventionally, in a printing apparatus that prints an image by ejecting ink droplets onto a printing medium, such as an ink jet printer, a printing apparatus that uses white ink in addition to chromatic ink such as cyan, magenta, and yellow, or black ink ( For example, a printing apparatus using a colorless or light clear ink (see, for example, Patent Document 2) is known.
The white ink is used, for example, to form a base layer for printing a color image on a transparent print medium or a chromatic print medium. The clear ink is used, for example, to promote predetermined wetting and fixing of ink droplets with chromatic color ink or black ink.
By the way, in such a printing apparatus, by reducing the size of the dots constituting the contour portion of the image to be printed or reducing the number of dots formed on the contour portion (image edge processing), There is known a method (see Patent Document 3) for improving image quality by preventing ink bleeding from occurring in an image outline.

JP 2009-241419 A JP-A-10-250216 JP 2011-167896 A

However, in the method described in Patent Document 3, the size of the contour of the image is reduced by reducing the size of the dots constituting the contour of the image to be printed or by reducing the number of dots formed on the contour. Although ink bleeding is suppressed and the contour portion can be made smoother, there is a problem in that the effect of using white ink or clear ink may be deteriorated.
Specifically, for example, the surface of a transparent print medium or a chromatic color print medium is reduced by reducing the size of the white ink dots in the region constituting the contour portion of the image or reducing the number of dots. This is a problem that the covering rate as the covering underlayer may be insufficient and may be transparent. In addition, for example, when the size of the clear ink dots in the region constituting the image outline is reduced or the number of dots is reduced, the ink is insufficiently fixed in the image outline. It is a problem that there are cases.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following application examples or forms.

  Application Example 1 An image processing apparatus according to this application example includes a first ink and a second ink that acts on the print medium and / or the first ink on the print medium with respect to the print medium. Is an image processing apparatus that generates print data for causing a printing apparatus that prints a print image to execute printing based on image data corresponding to the print image by forming a plurality of dots by discharging A dot formation specification determining unit for determining a dot formation specification including a position for forming the dot and a size of the dot based on the image data; and print data generation for generating the print data based on the dot formation specification And a contour of a partial image included in the first print image based on the image data corresponding to the first print image formed by the first ink A first edge extraction unit that extracts a first edge pixel region including a pixel to be detected, and the dot formation specification determination unit discharges the first edge pixel region when determining the dot formation specification. The edge processing for reducing the discharge density of the first ink can be executed, and the edge processing for reducing the discharge density of the second ink discharged to the first edge pixel region is not executed. To do.

The image processing apparatus according to the application example ejects the first ink and the second ink acting on the first ink on the print medium and / or the first ink on the print medium to form a plurality of dots. An image processing apparatus that generates print data for causing a printing apparatus that prints a print image to execute printing based on image data corresponding to the print image.
The image processing apparatus also includes a dot formation specification determining unit that determines a dot formation specification including a dot formation position and a dot size based on the image data, and print data generation that generates print data based on the dot formation specification. A first edge pixel region including pixels constituting the contour of the partial image included in the first print image based on the image data corresponding to the first print image formed by the first portion and the first ink And a first edge extraction unit.

  According to this application example, the dot formation specification determination unit can execute edge processing for reducing the discharge density of the first ink discharged to the first edge pixel region when determining the dot formation specification. Edge processing for reducing the discharge density of the second ink discharged to the edge pixel region is not executed. That is, the edge processing for the first edge pixel region performed when determining the dot formation specification is processing for the first print image using the first ink, and therefore the second ink in the first edge pixel region. Can be prevented from being insufficiently discharged (insufficiently imparted). As a result, it is possible to suppress an insufficient effect (for example, covering of a printing medium as a base layer or improvement of weather resistance of a printed image) that the second ink should exhibit in the first edge pixel region.

  Application Example 2 In the image processing device according to the application example, the edge process is a process of reducing the diameter of the dots and / or a process of reducing the number of dots formed.

  According to this application example, the edge that decreases the ejection density of the first ink ejected to the first edge pixel region (the pixel region that includes the pixels constituting the outline of the partial image included in the first print image). The process is a process of reducing the dot diameter and / or a process of reducing the number of dots formed. By reducing the diameter of the dots and / or reducing the number of dots formed, the discharge density of the first ink discharged and applied to the first edge pixel region can be reduced. It is possible to reduce the degree of ink bleeding that occurs in the contour portion of the partial image included in the print image, and it is possible to suppress a decrease in edge quality.

  Application Example 3 In the image processing apparatus according to the application example described above, based on the image data corresponding to the second print image configured by the second ink, the contour of the partial image included in the second print image A second edge extraction unit that extracts a second edge pixel region including the pixels that form a pixel, and the dot formation specification determination unit discharges the second edge pixel region when determining the dot formation specification. It is possible to execute edge processing for reducing the discharge density of the second ink.

The image processing apparatus according to the application example includes a second pixel that includes a pixel that forms an outline of a partial image included in the second print image, based on image data corresponding to the second print image formed by the second ink. A second edge extraction unit for extracting the edge pixel region.
In addition, the dot formation specification determination unit can execute edge processing for reducing the discharge density of the second ink discharged to the second edge pixel region when determining the dot formation specification.
According to this application example, the edge processing for reducing the ejection density of the second ink is performed on the contour region in the second print image with the second ink, so that the contour region in the first print image is performed. On the other hand, the second ink does not become insufficiently discharged (insufficiently applied). As a result, the action that the second ink should exhibit in the first edge pixel region is suppressed from becoming insufficient.

  Application Example 4 In the image processing apparatus according to the application example, the second ink is a white ink containing a white color material.

  For example, when a transparent resin film or chromatic paper is used for the print medium, it is preferable to use a white ink containing a white color material as the second ink, as in this application example. A simple underlayer can be formed.

  Application Example 5 In the image processing apparatus according to the application example, the second ink is a clear ink that does not substantially include a color material.

  As in this application example, it is preferable to use, as the second ink, for example, a clear ink that does not substantially include a color material as a working liquid that does not affect the color tone of a printed image. The working liquid is, for example, a working liquid that improves the fixability and abrasion resistance of the first ink to the printing medium, a working liquid that suppresses the deterioration of the color tone of the printed image and improves the weather resistance, and the first ink is wet There are working fluids that control spreading, and working fluids that improve the color tone and print quality of printed images.

  Application Example 6 A printing apparatus according to this application example includes the image processing apparatus according to the application example.

  According to this application example, since the printing apparatus includes the image processing apparatus according to the application example described above, the first edge pixel area (the pixel area including the pixels constituting the contour of the partial image included in the first print image is included) ), The second ink can be prevented from being insufficiently discharged (insufficiently applied). As a result, in printing that requires the second ink, the effects that the second ink should exert (for example, covering the print medium as the underlayer and improving the weather resistance of the printed image) are suppressed. Printing can be performed.

  Application Example 7 An image processing method according to this application example includes a first ink and a second ink that acts on the print medium and / or the first ink on the print medium with respect to the print medium. Is an image processing method for generating print data for causing a printing apparatus that prints a print image to execute printing based on image data corresponding to the print image by forming a plurality of dots by discharging A dot formation specification determining step for determining a dot formation specification including a position for forming the dot and a size of the dot based on the image data; and print data generation for generating the print data based on the dot formation specification And a contour of the partial image included in the first print image based on the process and the image data corresponding to the first print image constituted by the first ink. A first edge extraction step of extracting a first edge pixel region including a pixel to be formed, wherein the dot formation specification determination step includes the step of determining the dot formation specification in the first edge pixel region. Edge processing for reducing the discharge density of the first ink to be discharged can be executed, and edge processing for reducing the discharge density of the second ink to be discharged to the first edge pixel region is not executed. And

In the image processing method of this application example, the first ink and the second ink acting on the first ink on the print medium and / or the second ink acting on the print medium are ejected onto the print medium to form a plurality of dots. This is an image processing method for generating print data for causing a printing apparatus that prints a print image to execute printing based on image data corresponding to the print image.
The image processing method also includes a dot formation specification determining step for determining a dot formation specification including a dot formation position and a dot size based on the image data, and print data generation for generating print data based on the dot formation specification. Based on the process and image data corresponding to the first print image constituted by the first ink, a first edge pixel region including pixels constituting the contour of the partial image included in the first print image is extracted. A first edge extracting step.

  According to this application example, the dot formation specification determination step can execute edge processing for reducing the discharge density of the first ink discharged to the first edge pixel region when determining the dot formation specification. Edge processing for reducing the discharge density of the second ink discharged to the edge pixel region is not executed. That is, the edge processing for the first edge pixel region performed when determining the dot formation specification is processing for the first print image using the first ink, and therefore the second ink in the first edge pixel region. Can be prevented from being insufficiently discharged (insufficiently imparted). As a result, it is possible to suppress an insufficient effect (for example, covering of a printing medium as a base layer or improvement of weather resistance of a printed image) that the second ink should exhibit in the first edge pixel region.

  Application Example 8 In the image processing method according to the application example, the edge process is a process of reducing the diameter of the dots and / or a process of reducing the number of dots formed.

  According to this application example, the edge that decreases the ejection density of the first ink ejected to the first edge pixel region (the pixel region that includes the pixels constituting the outline of the partial image included in the first print image). The process is a process of reducing the dot diameter and / or a process of reducing the number of dots formed. By reducing the diameter of the dots and / or reducing the number of dots formed, the discharge density of the first ink discharged and applied to the first edge pixel region can be reduced. It is possible to reduce the degree of ink bleeding that occurs in the contour portion of the partial image included in the print image, and it is possible to suppress a decrease in edge quality.

  Application Example 9 In the image processing method according to the application example, the outline of the partial image included in the second print image based on the image data corresponding to the second print image configured by the second ink. A second edge extraction step for extracting a second edge pixel region including the pixels constituting the pixel, wherein the dot formation specification determination step discharges the second edge pixel region when determining the dot formation specification. It is possible to execute edge processing for reducing the discharge density of the second ink.

The image processing method of this application example includes a second pixel that includes a pixel that forms an outline of a partial image included in the second print image, based on image data corresponding to the second print image formed by the second ink. A second edge extraction step of extracting the edge pixel region.
In the dot formation specification determination step, edge processing for reducing the discharge density of the second ink discharged to the second edge pixel region can be executed when determining the dot formation specification.
According to this application example, the edge processing for reducing the ejection density of the second ink is performed on the contour region in the second print image with the second ink, so that the contour region in the first print image is performed. On the other hand, the second ink does not become insufficiently discharged (insufficiently applied). As a result, the action that the second ink should exhibit in the first edge pixel region is suppressed from becoming insufficient.

  Application Example 10 An image processing program according to this application example is characterized in that, in the image processing apparatus that generates print data described in the application example, the process of generating the print data can be executed.

  According to this application example, a plurality of dots are formed by ejecting the first ink and the second ink acting on the first ink on the print medium and / or the first ink on the print medium to the print medium. As a result, it is possible to generate print data for executing printing in which an operation that the second ink should exhibit is suppressed from being insufficient for a printing apparatus that prints a print image.

1 is a front view illustrating a configuration of a printing apparatus according to a first embodiment. 1 is a block diagram illustrating a configuration of a printing apparatus according to a first embodiment. Schematic diagram showing an example of the arrangement of nozzles in the print head Illustration of basic functions of the printer driver Conceptual diagram of edge extraction processing Matrix indicating the pixel to be calculated when performing edge extraction processing for each channel Matrix that shows an example of the gradation value of the pixel to be calculated Example of print image to be printed on print media Example of a dot matrix showing a base image and a letter T written on the base image Matrix showing examples of extracted edge pixels A dot matrix showing an example of a partial image of the first ink subjected to edge processing A dot matrix showing an example of a partial image by the second ink subjected to edge processing A dot matrix showing an example in which partial images of the first ink and the second ink subjected to edge processing are overlaid Matrix showing examples of edge pixels extracted in the prior art A dot matrix in which the edge T and the background image overlapped with the background image in the prior art 6 is a flowchart showing a flow of image processing in the first embodiment.

  DESCRIPTION OF EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention. In the following drawings, the scale may be different from the actual scale for easy understanding. Further, in the coordinates added to the drawings, the Z-axis direction is the vertical direction, the + Z direction is the upward direction, the X-axis direction is the front-rear direction, the -X direction is the forward direction, the Y-axis direction is the left-right direction, and the + Y direction is the left direction. The XY plane is a horizontal plane.

(Embodiment 1)
FIG. 1 is a front view showing the configuration of the printing apparatus 1 according to the first embodiment, and FIG. 2 is a block diagram of the same.
The printing apparatus 1 includes a printer 100 and an image processing apparatus 110 connected to the printer 100.
The printer 100 is an ink jet printer that prints a desired image on a long print medium 5 that is supplied in a rolled state based on print data received from the image processing apparatus 110.

<Basic configuration of image processing apparatus>
The image processing apparatus 110 includes a printer control unit 111, an input unit 112, a display unit 113, a storage unit 114, and the like, and controls a print job that causes the printer 100 to perform printing. The image processing apparatus 110 is configured using a personal computer as a preferred example.
Software for operating the image processing apparatus 110 includes general image processing application software (hereinafter referred to as an application) that handles image data to be printed, print data for controlling the printer 100 and causing the printer 100 to execute printing. Includes printer driver software to be generated (hereinafter referred to as printer driver). The printer driver is the “image processing program” in the present invention.
That is, the image processing apparatus 110 controls the printer 100 via print data for causing the printer 100 to print a print image based on the image data.
Note that the printer driver is not limited to an example configured as a functional unit by software, and may be configured by firmware, for example. For example, the firmware is mounted on an SOC (System on Chip) in the image processing apparatus 110.

The printer control unit 111 includes a CPU 115, an ASIC 116, a DSP 117, a memory 118, a printer interface unit (I / F) 119, and the like, and performs centralized management of the entire printing apparatus 1.
The input unit 112 is information input means as a human interface. Specifically, for example, a port to which a keyboard or an information input device is connected.
The display unit 113 is an information display unit (display) as a human interface, and is related to information input from the input unit 112, an image to be printed on the printer 100, and a print job under the control of the printer control unit 111. Information etc. are displayed.
The storage unit 114 is a rewritable storage medium such as a hard disk drive (HDD) or a memory card. The storage unit 114 stores software (a program operated by the printer control unit 111) that operates the image processing apparatus 110, images to be printed, and print jobs. Related information and the like are stored.
The memory 118 is a storage medium that secures an area for storing a program for the CPU 115 to operate, a work area for the operation, and the like, and includes a storage element such as a RAM or an EEPROM.

<Basic configuration of printer 100>
The printer 100 includes a printing unit 10, a moving unit 20, a control unit 30, and the like. The printer 100 that has received the print data from the image processing apparatus 110 controls the printing unit 10 and the moving unit 20 by the control unit 30 to print an image on the print medium 5 (image formation).
The print data is image formation data obtained by converting image data so that the printer 100 can print the image data using an application and printer driver included in the image processing apparatus 110, and includes a command for controlling the printer 100.
The image data includes, for example, general full color image information or text information obtained by a digital camera or the like.

The printing unit 10 includes a head unit 11, an ink supply unit 12, and the like.
The moving unit 20 includes a main scanning unit 40, a sub scanning unit 50, and the like. The main scanning unit 40 includes a carriage 41, a guide shaft 42, a carriage motor (not shown), and the like. The sub-scanning unit 50 includes a supply unit 51, a storage unit 52, a conveyance roller 53, a platen 55, and the like.

  The head unit 11 includes a print head 13 and a head control unit 14 having a plurality of nozzles (nozzle groups) that discharge printing ink (hereinafter referred to as ink) as ink droplets. The head unit 11 is mounted on the carriage 41 and reciprocates in the main scanning direction along with the carriage 41 moving in the main scanning direction (X-axis direction shown in FIG. 1). While the head unit 11 (printing head 13) moves in the main scanning direction, the ink droplets are ejected onto the printing medium 5 supported by the platen 55 under the control of the control unit 30, thereby forming dots along the main scanning direction. Are formed on the print medium 5.

  The ink supply unit 12 includes an ink tank and an ink supply path (not shown) that supplies ink from the ink tank to the print head 13. The ink tank, the ink supply path, and the ink supply path to the nozzle that ejects the same ink are provided independently for each ink.

  As the ink, for example, as a color ink set made of a dark ink composition, a four-color ink set obtained by adding black (K) to a three-color ink set of cyan (C), magenta (M), and yellow (Y) and so on. Further, for example, eight colors including ink sets such as light cyan (Lc), light magenta (Lm), light yellow (Ly), and light black (Lk) made of a light ink composition in which the density of each color material is lightened. There are color ink sets. The color ink (including black (K), light black (Lk), etc.) constituting these color ink sets is the “first ink” in the present invention.

The ink used by the printer 100 includes white ink (hereinafter referred to as white ink (W)) in addition to the color ink set for color printing. The white ink (W) is an ink for forming a base layer in the printed image, and is ejected before the color ink is ejected onto the printing medium 5.
For example, when a transparent resin film or a chromatic paper material is used as the printing medium 5, a white ink (W) and a sufficient undercoat layer are necessary to make the printed image a color image of a predetermined color. Form.
That is, the white ink (W) is a “second ink” that exhibits an action as a base layer that makes a printed image a color image of a predetermined color.
The white ink (W) ejection specifications (ink droplet size and ink droplet ejection density) may be determined in advance as appropriate specifications corresponding to the specifications of the print medium 5 under sufficient evaluation. preferable.

A piezo method is used as a method for ejecting ink droplets (inkjet method). The piezo method is a method in which a pressure corresponding to a print information signal is applied to ink stored in a pressure chamber by a piezoelectric element (piezo element), and ink droplets are ejected (discharged) from a nozzle communicating with the pressure chamber for printing.
The method for ejecting ink droplets is not limited to this, and other printing methods in which ink is ejected in droplets to form dot groups on the print medium 5 may be used. For example, a system in which ink is continuously ejected in droplets from a nozzle with a strong electric field between the nozzle and the acceleration electrode placed in front of the nozzle, and printing is performed by giving a print information signal from the deflection electrode while the ink droplet is flying, Alternatively, the ink droplets are ejected in accordance with the print information signal without deflecting (electrostatic suction method), the pressure is applied to the ink with a small pump, and the nozzle is mechanically vibrated with a crystal resonator or the like to force For example, a method of ejecting ink droplets, a method of heating and foaming ink with a microelectrode in accordance with a print information signal, and ejecting ink droplets to perform printing (thermal jet method) may be used.

The moving unit 20 (the main scanning unit 40 and the sub-scanning unit 50) moves the print medium 5 relative to the head unit 11 (print head 13) under the control of the control unit 30.
The guide shaft 42 extends in the main scanning direction and supports the carriage 41 in a slidable contact state, and the carriage motor serves as a drive source for reciprocating the carriage 41 along the guide shaft 42. That is, the main scanning unit 40 (carriage 41, guide shaft 42, carriage motor) moves the carriage 41 (that is, the print head 13) in the main scanning direction along the guide shaft 42 under the control of the control unit 30. Let

The supply unit 51 rotatably supports a reel on which the print medium 5 is wound in a roll shape, and sends the print medium 5 to the transport path. The storage unit 52 rotatably supports a reel around which the print medium 5 is wound, and winds the print medium 5 that has been printed from the conveyance path.
The transport roller 53 includes a driving roller that moves the print medium 5 in the sub-scanning direction (Y-axis direction shown in FIG. 1) that intersects the main scanning direction, a driven roller that rotates as the print medium 5 moves, and the like. A conveyance path for conveying the medium 5 from the supply unit 51 to the storage unit 52 via the printing region of the printing unit 10 (the region in which the print head 13 moves in the main scanning direction on the upper surface of the platen 55) is formed.

The control unit 30 includes an interface unit (I / F) 31, a CPU 32, a memory 33, a drive control unit 34, and the like, and controls the printer 100.
The interface unit 31 is connected to the printer interface unit 119 of the image processing apparatus 110 and transmits / receives data between the image processing apparatus 110 and the printer 100. The image processing apparatus 110 and the printer 100 may be directly connected by a cable or the like, or may be indirectly connected via a network or the like. Further, data transmission / reception may be performed between the image processing apparatus 110 and the printer 100 via wireless communication.

The CPU 32 is an arithmetic processing device for controlling the entire printer 100.
The memory 33 is a storage medium that secures an area for storing a program for the CPU 32 to operate, a work area for the operation, and the like, and includes a storage element such as a RAM or an EEPROM.
The CPU 32 controls the printing unit 10 and the moving unit 20 via the drive control unit 34 according to the program stored in the memory 33 and the print data received from the image processing apparatus 110.

The drive control unit 34 controls driving of the printing unit 10 (head unit 11 and ink supply unit 12) and the moving unit 20 (main scanning unit 40 and sub-scanning unit 50) based on the control of the CPU 32. The drive control unit 34 includes a movement control signal generation circuit 35, a discharge control signal generation circuit 36, and a drive signal generation circuit 37.
The movement control signal generation circuit 35 is a circuit that generates a signal for controlling the movement unit 20 (the main scanning unit 40 and the sub-scanning unit 50) in accordance with an instruction from the CPU 32.
The ejection control signal generation circuit 36 generates a head control signal for selecting a nozzle for ejecting ink, selecting an ejection amount, controlling ejection timing, and the like according to an instruction from the CPU 32 based on the print data. It is.
The drive signal generation circuit 37 is a circuit that generates a basic drive signal including a drive signal for driving the piezoelectric element of the print head 13.
The drive control unit 34 selectively drives the piezoelectric elements corresponding to the respective nozzles based on the head control signal and the basic drive signal.

<Print head>
FIG. 3 is a schematic diagram illustrating an example of an arrangement of nozzles in the print head 13. FIG. 3 shows a state viewed from the lower surface of the print head 13.
As shown in FIG. 3, the print head 13 includes seven nozzle rows 130 (white ink nozzle row W, black ink nozzle row K) in which a plurality of nozzles for ejecting each ink are arranged at a predetermined nozzle pitch. , Cyan ink nozzle array C, magenta ink nozzle array M, yellow ink nozzle array Y, light magenta ink nozzle array LM, and light cyan ink nozzle array LC). The nozzle rows 130 are aligned and arranged so as to be parallel to each other at a constant interval (nozzle row pitch) along a direction (X-axis direction) intersecting the sub-scanning direction (Y-axis direction). It is out.

The nozzle row 130 includes two nozzle chips 131 that extend in the Y-axis direction and are arranged in series, and the nozzle chips 131 are aligned at regular intervals (nozzle pitch) along the sub-scanning direction (Y-axis direction). 200 nozzles # 1 to # 200 are arranged in parallel.
The nozzle chip 131 is manufactured by a MEMS (Micro Electro Mechanical Systems) manufacturing process using, for example, a silicon wafer as a basic material and applying a semiconductor process. The 200 nozzles included in the nozzle chip 131 have the same ink ejection characteristics, or An approximate “nozzle group” is formed.
In addition, each nozzle is provided with a drive element (piezoelectric element such as the piezo element described above) for driving each nozzle to eject ink droplets.

  With the above configuration, the control unit 30 supports the print head 13 along the guide shaft 42 with respect to the print medium 5 supplied to the print region by the sub-scanning unit 50 (the supply unit 51 and the transport roller 53). Is moved in the main scanning direction (X-axis direction) while the ink droplets are ejected (applied) from the print head 13 and the sub-scanning direction (Y that intersects the main scanning direction by the sub-scanning unit 50 (conveying roller 53)). A desired image is formed (printed) on the print medium 5 by repeating the transport operation (feed operation) for moving (sub-scanning) the print medium 5 in the axial direction.

<Basic functions of the printer driver>
FIG. 4 is an explanatory diagram of the basic functions of the printer driver.
Printing on the print medium 5 is started when print data is transmitted from the image processing apparatus 110 to the printer 100. The print data is generated by the printer driver.
The basic contents of the print data generation process will be described below with reference to FIG.

  The printer driver receives image data from the application, converts it into print data in a format that can be interpreted by the printer 100, and outputs the print data to the printer 100. When converting image data from an application into print data, the printer driver performs resolution conversion processing, color conversion processing, halftone processing, rasterization processing, command addition processing, and the like.

That is, the printer driver includes a resolution conversion processing unit, a color conversion processing unit, a halftone processing unit, a rasterization processing unit, a command addition processing unit, and the like that perform these processes as functional units using software (or firmware) ( (Not shown).
The resolution conversion processing unit, the color conversion processing unit, and the halftone processing unit constitute a “dot formation specification determination unit” that determines the dot formation specification including the dot formation position and the dot size based on the image data. . The description of the dot formation specification determination unit will be described later.
The rasterization processing unit and the command addition processing unit constitute a “print data generation unit” that generates print data based on the dot formation specification determined by the dot formation specification determination unit.
The printer driver (image processing program) performs processing according to the following procedure in each functional unit.

The resolution conversion process is a process of converting the image data output from the application into a resolution (print resolution) when printing on the print medium 5. For example, when the print resolution is specified as 720 × 720 dpi, vector format image data received from the application is converted into bitmap format image data with a resolution of 720 × 720 dpi. Each pixel data of the image data after the resolution conversion process is composed of pixels arranged in a matrix. Each pixel has a gradation value of, for example, 256 gradations (a predetermined number of gradations) in the RGB color space. That is, the pixel data after resolution conversion indicates the gradation value of the corresponding pixel.
Pixel data corresponding to one column of pixels arranged in a predetermined direction among pixels arranged in a matrix is called raster data. The predetermined direction in which the pixels corresponding to the raster data are arranged corresponds to the moving direction (main scanning direction) of the print head 13 when printing an image.

The color conversion process is a process for converting RGB data into data in the CMYK color system space. The CMYK colors are cyan (C), magenta (M), yellow (Y), and black (K), and the image data in the CMYK color system space is data corresponding to the ink color that the printer 100 has. Therefore, for example, when the printer 100 uses 10 types of inks of the CMYK color system, the printer driver generates image data in a 10-dimensional space of the CMYK color system based on the RGB data.
This color conversion processing is performed based on a table (color conversion lookup table LUT) in which gradation values of RGB data and gradation values of CMYK color system data are associated with each other. The pixel data after the color conversion processing is, for example, CMYK color system data of 256 gradations (predetermined number of gradations) represented by the CMYK color system space.

The halftone process is a process for converting, for example, data of 256 gradations (predetermined number of gradations) to data of the number of gradations that can be formed by the printer 100 (number of gradations lower than the predetermined number of gradations). By this halftone processing, for example, data indicating 256 gradations is converted into, for example, 1-bit data indicating 2 gradations (with or without dots) or 4 gradations (without dots, small dots, medium dots, large dots). It is converted into halftone data that determines dot formation specifications, such as 2-bit data shown. Specifically, from the dot generation rate table corresponding to the gradation value (0 to 255) and the dot generation rate, the dot generation rate corresponding to the gradation value (for example, in the case of 4 gradations, no dot, small Pixel data is created so that dots are formed in a dispersed manner using the dither method, error diffusion method, etc. at the obtained generation rate. The As described above, in the halftone process, halftone data for determining the formation specifications of the dots formed by the nozzle group that ejects the same color (or the same kind) of ink is generated.
That is, the halftone data arranged in a matrix form is data indicating the dot formation specifications including the dot formation position and the dot size.

  The rasterization process is a process of rearranging pixel data arranged in a matrix (for example, 1-bit or 2-bit halftone data as described above) according to the dot formation order at the time of printing. In the rasterizing process, the image data constituted by the pixel data (halftone data) after the halftone process is assigned to each pass operation in which the print head 13 (nozzle array) ejects ink droplets while moving in the main scanning. Is included. When the allocation process is completed, the pixel data arranged in a matrix is allocated to the actual nozzles forming each raster line constituting the print image in each pass operation.

The command addition process is a process for adding command data corresponding to the printing method to the rasterized data. The command data includes, for example, transport data related to the transport specifications of the print medium 5 (the amount of movement and speed in the sub-scanning direction (Y-axis direction)).
These processes by the printer driver are performed by the ASIC 116 and the DSP 117 (see FIG. 2) under the control of the CPU 115, and the generated print data is transmitted to the printer 100 via the printer interface unit 119 by the print data transmission process. Is done.

<Contour maintenance processing>
In addition to the basic functions of the printer driver described above, the printer driver of this embodiment further includes a contour maintenance processing function.
The contour maintenance processing function is a function for improving the image quality by making the contour of a partial image such as characters and lines included in a print image smoother (suppressing the disturbance of the contour).
In general printing, the dots formed by ink droplets are absorbed by the print medium to fix the printed image on the print medium. However, ink droplets are ejected onto the print medium at a density that exceeds the absorption capacity of the print medium. When applied, the print medium may not absorb ink droplets and the ink may overflow. The overflow of ink means that a part of the ink droplet moves from the landing position. In particular, if ink overflows in the contour (edge pixel area) of the image to be printed, the ink will flow out to the portion where the image should not be formed. As a result, the contour of the image is disturbed, and the image quality of the printed image Will deteriorate. Therefore, by performing the contour maintenance process for reducing the amount of ink ejected to the edge pixel area of the printed image, it is possible to suppress the overflow of ink at the edge portion.
The contour maintenance processing function provided in the image processing apparatus according to the present embodiment will be described below.

The contour maintenance processing function includes functions such as edge extraction processing and edge processing.
That is, the printer driver of the present embodiment further includes a contour maintenance processing unit as a functional unit by software (or firmware) (see FIG. 16 described later). The contour maintenance processing unit is a functional unit in the dot formation specification determination unit, and includes an edge extraction unit, an edge processing unit, and the like (not shown).

The edge extraction unit includes a color edge extraction unit and a base edge extraction unit (see FIG. 5 described later).
The color edge extraction unit is the “first edge extraction unit” in the present invention. The base edge extraction unit is a “second edge extraction unit” in the present invention.
The color edge extraction unit is a functional unit that extracts a pixel region including edge pixels that form the outline of a partial image included in a print image configured with color ink.
The print image constituted by the color ink (first ink) is the “first print image” in the present invention. Hereinafter, for the sake of clarity, the first print image is referred to as a color print image. The pixel region including the edge pixels constituting the contour of the partial image included in the color print image is the “first edge pixel region” in the present invention. Hereinafter, the first edge pixel region is referred to as a color edge pixel region.

The background edge extraction unit is a functional unit that extracts a pixel region including edge pixels that form the contour of a partial image included in an image as a background layer formed of white ink (W).
The print image constituted by the white ink (W) (second ink) is the “second print image” in the present invention. Hereinafter, for the sake of clarity, the second print image is referred to as a base image. The pixel area including the edge pixels constituting the contour of the partial image included in the base image is the “second edge pixel area” in the present invention. Hereinafter, the second edge pixel region is referred to as a base edge pixel region.

The edge processing unit forms dots so as to reduce the discharge density of the color ink and white ink (W) discharged to the color edge pixel region and the background edge pixel region that are the target regions of the contour maintenance process extracted by the edge extraction unit. It is a functional part that sets specifications.
The processing of each functional unit will be specifically described below.

<Edge extraction processing>
The edge extraction process is a process of extracting edge pixels constituting the contour of the partial image included in the print image based on the image data, and extracting an edge pixel region that is an object of the edge process. The partial image is a character, line, pattern, or the like included in the print image. In other words, the edge pixels extracted by the edge extraction process described below and an image surrounded by the edge pixels can also be called partial images.

FIG. 5 is a conceptual diagram of edge extraction processing.
The edge extraction process is divided into a color edge extraction process performed in the color edge extraction unit (color edge extraction process) and a background edge extraction process performed in the background edge extraction unit (background edge extraction process).
The color edge extraction step is a “first edge extraction step” in the present invention, and the base edge extraction step is a “second edge extraction step” in the present invention.

In the color edge extraction process, a color edge pixel region including edge pixels that form the contour of a partial image included in the color print image G1 is extracted based on the image data D1 corresponding to the color print image G1.
In the color edge extraction processing, first, RGB image data (R, G, B) of the color print image G1 is decomposed into red (R), green (G), and blue (B) channels, and each channel is separated. Edge pixels (Rf, Gf, Bf) are extracted. The edge pixel extraction algorithm will be described later.
Next, the pixels at positions determined as edge pixels in each channel are merged, and the result is extracted as edge pixels RGBf of the partial image included in the color print image G1.

  Next, an edge pixel region RGBm (color edge pixel region) to be subjected to subsequent edge processing is determined for the edge pixel RGBf extracted by the edge extraction processing. The target range (edge pixel region RGBm) for performing edge processing on the extracted edge pixel RGBf is set in advance by setting the surrounding pixel range centering on the edge pixel RGBf as the number of pixel pitches away from the edge pixel RGBf. deep. The number of pitches that designates this range is preferably determined appropriately as a result of sufficient evaluation in advance corresponding to the characteristics of the material and ink used for the print medium 5. It may be changed according to designation by the user of the image processing apparatus 110. The designation by the user can be input from the input unit 112 via a user interface screen (UI screen) displayed on the display unit 113 as a function of the printer driver, for example.

In the background edge extraction process, a background edge pixel area including edge pixels that form the contour of the partial image included in the background image G2 is extracted based on the image data D2 corresponding to the background image G2 formed by the white ink (W). .
Since the image data D2 is a single channel of white ink (W), the edge pixel Wf is extracted from the image data D2 as it is.
Next, for the edge pixel Wf extracted by the edge extraction process, an edge pixel area Wm (background edge pixel area) to be subjected to subsequent edge processing is determined. The target range (edge pixel region Wm) on which the edge processing is performed on the extracted edge pixel Wf is the number of pixel pitches that are separated from the edge pixel Wf independently of the color edge extraction processing, as in the color edge extraction processing. Can be specified.

<Edge pixel extraction algorithm>
FIG. 6 is a matrix showing calculation target pixels when performing edge extraction processing for each channel.
The edge extraction processing is performed using target pixels (target pixels) for determining whether or not they are edge pixels and image data (gradation values) of four pixels among the surrounding 3 × 3 pixels. Among the 3 × 3 pixels shown in FIG. 6, the pixel 0 is the target pixel, and the pixels 2, 4, 5, and 7 are calculation target pixels for determination.
Whether or not the pixel is an edge pixel is determined based on a difference between the gradation value of the pixel of interest 0 and the gradation values of the surrounding pixels 2, 4, 5, and 7. The difference between the gradation value of the pixel of interest 0 and the gradation value of any one of the pixels 2, 4, 5, and 7 exceeds a predetermined threshold, and the gradation value (density) of the pixel of interest 0 is predetermined. When it is larger than the gradation value of the surrounding pixels exceeding the threshold, the target pixel 0 is determined as an edge pixel.
Further, the target pixel 0 when there is no calculation target pixel around the target pixel 0 is regarded as an end pixel, and the end pixel is also determined as an edge pixel.

  Note that the predetermined threshold for determining the edge pixel is preferably set in advance as an appropriate value, but can be changed according to the designation of the user (the user of the printing apparatus 1 or the image processing apparatus 110). Also good. The designation by the user can be input from the input unit 112 via a user interface screen (UI screen) displayed on the display unit 113 as a function of the printer driver, for example.

FIG. 7 is a matrix showing an example of the gradation value of the calculation target pixel.
If the determination threshold is 90, for example, the difference between the gradation value 120 of the pixel of interest 0 and the gradation value 25 of the surrounding pixel 2 is 95, so the pixel of interest 0 is determined as an edge pixel. The

  Note that the edge extraction processing is not limited to the above-described method as long as it is a method for determination based on the degree or distribution of gradation value differences. For example, a calculation method may be performed on eight pixels around the target pixel 0, or a determination method may be performed based on the degree of gradient of change in gradation value in a wider range.

<Edge processing>
Edge processing is converted into data that reduces the discharge density of ink (color ink, white ink (W)) discharged to the edge pixel area (color edge pixel area, base edge pixel area) described above when determining dot formation specifications. It is processing to do. A discharge density means the ratio of the dot formation area per unit area.
In the edge processing of the present embodiment, when determining the dot formation specification, it is converted into data for decreasing the discharge density of the color ink discharged to the color edge pixel area, and the discharge density of the white ink (W) discharged to the base edge pixel area The data is converted to data that decreases That is, in the edge processing, the discharge density of the white ink (W) discharged to the color edge pixel region is not reduced.

As a method of reducing the ink discharge density, there are a method of reducing the size of ink droplets (reducing the diameter of dots), a method of reducing the discharge density of ink droplets, and the like.
The method of reducing the ink droplet size (decreasing the diameter of the dot) is that the halftone data indicates a plurality of dot sizes such as four gradations (no dots, small dots, medium dots, large dots). This is a method of converting to smaller dots when the data is composed of two or more bits.

  One method for converting to smaller dots is to convert the dot size (ink droplet size) to smaller size data after generating halftone data. That is, the halftone data is changed to a dot size smaller by one size (or two sizes). Note that reducing the size by 1 for small dots and reducing the size by 2 for medium dots means changing to “no dot”.

  As another method of converting to smaller dots, there is a method of converting the gradation value to a smaller value for the CMYK color image data before the halftone process, that is, after the color conversion process. Specifically, for example, in CMYK color image data after color conversion processing, pixel data having a predetermined gradation number corresponding to ink ejection (applying) is changed to a smaller gradation number (for example, a value of 1/2). ).

  The method of reducing the density of ink droplet ejection is a method of generating print data in which the printing apparatus 1 is controlled so that the density of ink droplet ejection is reduced. That is, this is a method of reducing the number of ejections of ink droplets to be ejected (number of dots formed).

  As a method of reducing the ink discharge density, a method of combining a method of reducing the size of ink droplets (reducing the dot diameter) and a method of reducing the discharge density may be used. Specifically, this is a method of reducing the discharge density while converting the dot size (ink droplet size) to a smaller size.

  The method of reducing the ink discharge density and the degree thereof (edge processing strength) may vary depending on the specifications of the print medium 5, and the degree of disturbance of the contour of the partial image may differ. It is preferable to set an appropriate specification corresponding to each specification of the print medium 5. In addition, the permissible level with respect to the degree of disturbance of the outline of the partial image varies depending on the type and purpose of the partial image, the preference of the user (user of the printing apparatus 1 or the image processing apparatus 110), and the like. Anyway. The designation by the user can be input from the input unit 112 via a user interface screen (UI screen) displayed on the display unit 113 as a function of the printer driver, for example.

<Example of contour maintenance processing>
FIG. 8 is an example of a print image G to be printed on the print medium 5.
The print image G is composed of a base image G2 of the base layer constituted by white ink (W) and a color print image G1 formed on the upper layer of the base image G2 by color ink.
The color print image G1 shown in FIG. 8 is an image of three characters (A, B, T) with black ink (K), and the base image G2 is below each of the three characters (A, B, T). It is an image of a ground image (Wa, Wb, Wt) constituting the formation.
Character A, character B, and character T are partial images included in the color print image G1, respectively. Further, the base image Wa, the base image Wb, and the base image Wt are partial images included in the base image G2.

Hereinafter, description will be made by paying attention to the base image Wt and the character T written on the base image Wt.
FIG. 9 is an example of a dot matrix indicating the base image Wt and the character T written in the base image Wt.
The base image Wt is composed of white ink (W) of 23 × 24 large dots, and the letter T is composed of a horizontal line of 17 × 3 large dots by black ink (K) and a large dot of 3 × 14. It consists of vertical lines.
The black circles and white circles shown in FIG. 9 indicate the landing state of the ink droplets, and the dots that are actually formed are such that the ink droplets penetrate the surface of the print medium 5 and the gaps between the black circles and the white circles are reduced. Spread wet.

FIG. 10 is a matrix showing an example of edge pixels extracted from the image shown in FIG.
A black circle indicates the position of the edge pixel constituting the outline of the character T included in the color print image G1 formed by the black ink (K), and a white circle indicates the background image included in the background image G2 formed by the white ink (W). The position of the edge pixel which comprises the outline of Wt is shown.
The outline in the background image Wt is performed independently of the image data corresponding to the character T based on the image data corresponding to the background image Wt by the background edge extraction unit. Extracted.
Edge pixel regions (color edge pixel region and background edge pixel region) as the target region of edge processing are determined as pixel regions including these edge pixels. Here, only the position of the edge pixel is used as the edge pixel region. explain. That is, the case where the pixel pitch number n (the number of pixel pitches away from the edge pixel) for designating the range for setting the edge pixel region is n = 0 will be described.

FIG. 11 shows the ink droplet landing state of the black ink (K) constituting the character T when the edge processing is performed on the set edge pixel region. In the edge processing, the edge pixel area of the character T (here, the edge pixel constituting the outline of the character T) is changed from a large dot to a small dot.
FIG. 12 shows the ink droplet landing state of the white ink (W) constituting the base image Wt when the edge processing is performed on the set edge pixel region. Similarly in this edge processing, the edge pixels constituting the contour of the background image Wt are changed from large dots to small dots.

FIG. 13 shows a dot matrix in which the edge-processed character T and the base image Wt are overlapped. That is, it is a dot matrix indicating the ink droplet landing state corresponding to the actual printing state.
As can be seen from the figure, ink droplets that form small dots are applied to the positions of edge pixels that form the outline of the letter T instead of ink droplets that form large dots. As a result, the black ink (K) is prevented from overflowing at the position of the edge pixel constituting the outline of the character T and the outline is disturbed, and the letter T can be printed with a smooth outline.
For the base image Wt, only the outermost peripheral pixels constituting the base image Wt are extracted as edge pixel regions, and the positions of the edge pixels constituting the outline of the character T and the surrounding pixels are large. It remains a dot. That is, unlike the prior art described below, the coverage as a base layer covering the surface of the print medium 5 does not become insufficient near the outline of the character T.

FIG. 14 is a matrix showing an example of edge pixels extracted in the prior art for the image shown in FIG.
In the prior art, the base image G2 of the base layer composed of the white ink (W) is not subjected to edge extraction and edge processing independently. In the case of the image shown in FIG. The edge pixel of the base image Wt for the character T is extracted. Therefore, as shown in FIG. 14, for the base image Wt, the surrounding pixels of the character T are extracted as edge pixels.

FIG. 15 shows a dot matrix in which a character T subjected to edge processing and a base image Wt are overlapped with each other in the prior art.
In the prior art, an area including edge pixels around the character T is extracted as an edge pixel area, and edge processing (processing for reducing ink discharge density) is performed on the entire edge pixel area including the edge pixel area. In other words, since the process of reducing the discharge density of the white ink (W) has been performed, for example, there is a region where the coverage as the underlayer is insufficient, such as a region surrounded by a broken line in FIG. Was.

<Image processing flow>
FIG. 16 is a flowchart showing a flow of image processing in the present embodiment.
An image processing method according to the present embodiment, that is, a print data generation method based on image data will be described with reference to a flowchart.
First, image data (RGB data) for printing is acquired (step S1).
Next, the specification of the base image for printing (the base image G2 of the base layer constituted by the white ink (W)) is determined (step S2). Specifically, the area for printing the background image G2 and the gradation value (density) are determined. These specifications are prepared as specifications corresponding to the specifications of the print medium 5 and the image to be printed. However, the prepared specifications can be changed each time printing is performed.

Next, the image data acquired in step S1 and the image data corresponding to the base image G2 determined in step S2 are converted into a resolution (printing resolution) for printing on the print medium 5 (step S3). By this resolution conversion processing, the image data (D1, D2) shown in FIG. 5 is obtained.
Next, the edge extraction process of the partial image is performed based on the image data (D1, D2) for which the resolution conversion process has been completed (step S4, edge extraction process). Specifically, edge pixels (RGBf, Wf (see FIG. 5)) of the partial image are obtained, and edge pixel regions (RGBm, Wm (see FIG. 5)) are determined based on the extracted edge pixels (RGBf, Wf). To do. At this time, if necessary, the predetermined threshold value for determining the edge pixel and the pixel pitch number n (the number of pixel pitches away from the edge pixel) for designating the range for setting the edge pixel region are changed. Can do.
Here, the color edge extraction step for extracting the edge pixel region RGBm (color edge pixel region) is the “first edge extraction step” in the present invention, and the background for extracting the edge pixel region Wm (background edge pixel region). The edge extraction step is a “second edge extraction step” in the present invention.

  Next, color conversion processing is performed on the image data (D1, D2) for which resolution conversion processing has been completed in step S3 to obtain CMYK color image data (step S5). Since the image data D2 is a single channel of white ink (W), there is no need to perform color conversion processing when it is set in advance as CMYK color image data.

Next, halftone processing is performed on the CMYK color image data to generate halftone data indicating dot formation specifications including dot formation positions and dot sizes (step S6 (halftone processing step)). ).
The CMYK color image data is, for example, data composed of pixel data of 256 gradations (predetermined number of gradations). As described above, the halftone data is lower than the predetermined gradation number constituting the dot formation specification. Data consisting of logarithmic pixel data (1 bit data indicating 2 gradations (with and without dots) and 2 bit data indicating 4 gradations (without dots, small dots, medium dots and large dots)).
Next, among the halftone data obtained by the halftone process, for the halftone data of the color ink, the edge process is performed on the data of the edge pixel region RGBm, and the halftone data of the white ink (W) In step S7, edge processing is performed on the data of the edge pixel region Wm. That is, edge processing is not performed on the data of the edge pixel region RGBm for the halftone data of white ink (W).
The process from step S3 to step S7 is a “dot formation specification determination process” for determining a dot formation specification including a dot formation position and a dot size based on the image data.

Next, rasterization processing is performed on the halftone data (step S8), and finally command addition processing is performed to generate print data (step S9), thereby completing the processing.
The steps S8 and S9 are “print data generation steps” for generating print data based on the dot formation specifications.

Note that step S6 (halftone processing step) and step S7 (edge processing step) have been described as independent processes, that is, step S7 (edge processing step) is performed after step S6 (halftone processing step). As described above, halftone data may be generated while performing edge processing.
Specifically, when image data converted into the CMYK color system is subjected to halftone processing for each individual pixel according to the dot generation rate table, pixels corresponding to the edge pixel region (RGBm, Wm) A method of generating halftone data while performing a process of reducing the ink discharge density in accordance with the set edge processing intensity may be used.

As described above, according to the image processing apparatus, the printing apparatus, the image processing method, and the image processing program according to the present embodiment, the following effects can be obtained.
The dot formation specification determination unit included in the image processing apparatus of the present embodiment reduces the discharge density of the color ink discharged to the color edge pixel region (the region constituting the contour of the partial image using color ink) when determining the dot formation specification. The edge processing to be performed can be executed, and the edge processing to reduce the discharge density of the white ink (W) discharged to the color edge pixel region is not executed. That is, since the edge processing for the color edge pixel region performed when determining the dot formation specification is processing for a color print image with color ink, white ink (W) is insufficiently ejected (unapplied) in the color edge pixel region. Can be eliminated. As a result, it is suppressed that the action (covering the printing medium 5 as a base layer) that the white ink (W) should exhibit in the color edge pixel region is insufficient.

  The edge process for reducing the discharge density of the color ink discharged to the color edge pixel area is a process for reducing the dot diameter and / or a process for reducing the number of dots formed. By this edge processing, the discharge density of the color ink discharged to the color edge pixel region can be reduced. For example, the degree of ink bleeding that occurs in the contour portion of the partial image included in the color print image is reduced. And the deterioration of the edge quality can be suppressed.

In addition, the image processing apparatus 110 according to the present embodiment is based on image data corresponding to a background image formed of white ink (W), and includes a background edge pixel area including pixels that form the contour of a partial image included in the background image. A background edge extraction unit is provided for extracting (a region constituting the outline of the partial image by white ink (W)). When determining the dot formation specification, the dot formation specification determination unit can execute edge processing for reducing the discharge density of the white ink (W) discharged to the base edge pixel region.
According to the present embodiment, the edge processing for reducing the discharge density of the white ink (W) is performed on the contour area (background edge pixel area) in the background image with the white ink (W), so that the color print image is displayed. The white ink (W) does not become insufficiently discharged (insufficiently applied) with respect to the contour area in FIG. As a result, the action that the white ink (W) should exhibit in the color edge pixel region is suppressed from becoming insufficient.

  Also, when a transparent resin film or chromatic paper is used for the print medium 5 and a white ink (W) containing a white color material is used as the second ink, the white ink (W) is insufficiently discharged. A good underlayer can be formed without causing (insufficient provision).

  In addition, since the printing apparatus 1 includes the image processing apparatus 110, the area in which the white ink (W) is insufficiently ejected (unapplied) in printing that requires a base layer using the white ink (W) by using the printing apparatus 1. And good printing can be performed.

  Further, according to the image processing method of the present embodiment, the dot formation specification determination step includes the step of determining the color ink to be ejected to the color edge pixel region (the region constituting the contour of the partial image using color ink) when determining the dot formation specification. Edge processing for reducing the discharge density can be executed, and edge processing for reducing the discharge density of the white ink (W) discharged to the color edge pixel region is not executed. That is, since the edge processing for the color edge pixel region performed when determining the dot formation specification is processing for a color print image with color ink, white ink (W) is insufficiently ejected (unapplied) in the color edge pixel region. Can be eliminated. As a result, it is suppressed that the action (covering the printing medium 5 as a base layer) that the white ink (W) should exhibit in the color edge pixel region is insufficient.

In addition, the image processing method according to the present embodiment is based on the image data corresponding to the background image formed by the white ink (W), and the background edge pixel region including the pixels constituting the outline of the partial image included in the background image is obtained. A base edge extraction step for extraction is provided.
In the dot formation specification determination step, edge processing for reducing the discharge density of the white ink (W) discharged to the base edge pixel region can be executed when determining the dot formation specification.
According to the present embodiment, the edge processing for reducing the discharge density of the white ink (W) is performed on the contour area (background edge pixel area) in the background image with the white ink (W), so that the color print image is displayed. The white ink (W) does not become insufficiently discharged (insufficiently applied) with respect to the contour area in FIG. As a result, the action that the white ink (W) should exhibit in the color edge pixel region is suppressed from becoming insufficient.

  In addition, the image processing program according to the present embodiment (that is, the program that can execute the process of generating print data in the image processing apparatus 110 or the process of generating print data in the above-described image processing method can be executed). According to the program, the white ink is applied to the printing apparatus 1 that prints the print image by ejecting the color ink and the white ink (W) to the print medium 5 to form a plurality of dots. It is possible to generate print data for executing printing in which the effect of the underlayer to be exhibited by (W) is suppressed.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be added to the above-described embodiment. A modification will be described below. Here, the same components as those in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.

(Modification 1)
In the first embodiment, it has been described that in the edge processing, the discharge density of the white ink (W) discharged to the color edge pixel region is not reduced. That is, the edge processing for the color edge pixel region is not performed for the white ink (W). Specifically, as described with reference to FIG. 13, with respect to the base image Wt, only the outermost peripheral pixels constituting the base image Wt are extracted as edge pixel regions, and form the outline of the character T. The position of the edge pixel and the surrounding pixels are not subject to edge processing of the background image Wt and remain large dots.
However, if the white ink (W) has a necessary and sufficient function as a base layer to be exhibited, the white ink is used in the color edge pixel region (the region constituting the contour of the partial image by the color ink). Edge processing for (W) may be performed.

  That is, in this modification, in the image processing apparatus 110, the dot formation specification determination unit reduces the discharge density of the white ink (W) discharged to the color edge pixel region within a predetermined range when determining the dot formation specification. Edge processing can be executed. In the image processing method, the dot formation specification determination step can execute edge processing for reducing the discharge density of the white ink (W) discharged to the color edge pixel region within a predetermined range when determining the dot formation specification. It is characterized by being.

Specifically, in the edge processing in the edge processing unit (edge processing step), when determining the dot formation specifications, it is converted into data that reduces the discharge density of the white ink (W) discharged to the color edge pixel region within a predetermined range. To do.
Here, the predetermined range is a range up to a limit where the action to be exerted by the white ink (W) is ensured in a necessary and sufficient range, and in advance according to the characteristics of the material and ink used for the print medium 5. It is preferable to appropriately determine the result as a result of performing sufficient evaluation in correspondence, but it may be changed according to designation by a user (a user of the printing apparatus 1 or the image processing apparatus 110).

According to the image processing apparatus (image processing method) according to this modification, the discharge density of the color ink and the white ink (W) discharged to the color edge pixel region is reduced. As a result, it is possible to suppress the color ink from overflowing and disturbing the outline at the position of the edge pixel constituting the outline of the color print image, and the color print image having a smooth outline can be printed.
Further, since the discharge density of the white ink (W) discharged to the color edge pixel region is a discharge density that ensures a necessary and sufficient range for the action that the white ink (W) should exhibit, the surface of the print medium 5 The covering ratio as a base layer covering the film does not become insufficient.

(Modification 2)
In the first embodiment, the white ink (W) is described as an example of the second ink. However, the second ink is not limited to the white ink (W). For example, the second ink that acts on the print medium 5 and / or the color ink on the print medium 5 may be a clear ink that does not substantially include a color material.
As the clear ink, a working liquid that improves the fixability and abrasion resistance of the color ink to the printing medium 5, a working liquid that suppresses the deterioration of the color tone of the printed image and improves the weather resistance, and controls the wetting and spreading of the color ink. There are working fluids, working fluids that improve the color tone and print quality of printed images.
Since the clear ink does not substantially include a color material, the clear ink does not affect the color tone of the printed image or has little effect.

  DESCRIPTION OF SYMBOLS 1 ... Printing apparatus, 5 ... Print medium, 10 ... Printing part, 11 ... Head unit, 12 ... Ink supply part, 13 ... Print head, 14 ... Head control part, 20 ... Moving part, 30 ... Control part, 31 ... Interface 32: CPU, 33: Memory, 34: Drive control unit, 35: Movement control signal generation circuit, 36: Discharge control signal generation circuit, 37 ... Drive signal generation circuit, 40 ... Main scanning unit, 41 ... Carriage, 42 DESCRIPTION OF SYMBOLS ... Guide shaft, 50 ... Sub-scanning part, 51 ... Supply part, 52 ... Storage part, 53 ... Conveyance roller, 55 ... Platen, 100 ... Printer, 110 ... Image processing apparatus, 111 ... Printer control part, 112 ... Input part, 113 ... Display unit, 114 ... Storage unit, 115 ... CPU, 116 ... ASIC, 117 ... DSP, 118 ... Memory, 119 ... Printer interface unit, 130 ... No Le column, 131 ... nozzle tip.

Claims (10)

Printing is performed by ejecting a first ink and a second ink that acts on the print medium and / or the first ink on the print medium to form a plurality of dots on the print medium. An image processing apparatus that generates print data for causing a printing apparatus that performs image printing to execute printing based on image data corresponding to the print image,
Based on the image data, a dot formation specification determination unit for determining a dot formation specification including a position for forming the dot and a size of the dot;
A print data generation unit that generates the print data based on the dot formation specifications;
Based on the image data corresponding to the first print image constituted by the first ink, a first edge pixel region including pixels constituting the outline of the partial image included in the first print image is extracted. A first edge extraction unit that performs
The dot formation specification determination unit can execute edge processing for reducing the discharge density of the first ink discharged to the first edge pixel region when determining the dot formation specification, and the first edge An image processing apparatus that does not execute edge processing for reducing the discharge density of the second ink discharged to the pixel region.   The image processing apparatus according to claim 1, wherein the edge processing is processing for reducing the diameter of the dots and / or processing for reducing the number of dots formed. Based on the image data corresponding to the second print image constituted by the second ink, a second edge pixel region including pixels constituting the outline of the partial image included in the second print image is extracted. A second edge extraction unit
The dot formation specification determination unit is capable of executing edge processing for reducing the discharge density of the second ink discharged to the second edge pixel region when determining the dot formation specification. The image processing apparatus according to claim 1 or 2.   The image processing apparatus according to claim 1, wherein the second ink is a white ink containing a white color material.   The image processing apparatus according to claim 1, wherein the second ink is a clear ink that does not substantially include a color material.   A printing apparatus comprising the image processing apparatus according to any one of claims 1 to 5. Printing is performed by ejecting a first ink and a second ink that acts on the print medium and / or the first ink on the print medium to form a plurality of dots on the print medium. An image processing method for generating print data for causing a printing apparatus for printing an image to execute printing based on image data corresponding to the print image,
Based on the image data, a dot formation specification determining step for determining a dot formation specification including a position for forming the dot and a size of the dot;
A print data generation step for generating the print data based on the dot formation specifications;
Based on the image data corresponding to the first print image constituted by the first ink, a first edge pixel region including pixels constituting the outline of the partial image included in the first print image is extracted. A first edge extraction step that includes:
In the dot formation specification determination step, when the dot formation specification is determined, an edge process for reducing a discharge density of the first ink discharged to the first edge pixel region can be executed, and the first edge An image processing method, wherein edge processing for reducing the discharge density of the second ink discharged to the pixel region is not executed.   The image processing method according to claim 7, wherein the edge process is a process of reducing the diameter of the dots and / or a process of reducing the number of dots formed. Based on the image data corresponding to the second print image constituted by the second ink, a second edge pixel region including pixels constituting the outline of the partial image included in the second print image is extracted. Including a second edge extraction step,
The dot formation specification determination step can execute an edge process for reducing a discharge density of the second ink discharged to the second edge pixel region when determining the dot formation specification. The image processing method according to claim 7 or 8.   6. An image processing program for generating print data according to claim 1, wherein the process for generating the print data can be executed. 7.

Images