JP5998596B2 - Print control apparatus and program - Google Patents

Description

  The present invention relates to a print control apparatus and a program.

  2. Description of the Related Art Printing apparatuses that perform printing using a liquid (for example, UV ink) that is cured by irradiation with light (a type of electromagnetic wave, for example, ultraviolet (UV)) are known. In such a printing apparatus, after a liquid is ejected from the nozzle of the head onto the medium, the dots formed on the medium are irradiated with light. By doing so, the dots are cured and fixed to the medium, so that it is possible to perform good printing even on a medium that hardly absorbs liquid (for example, see Patent Document 1).

JP 2000-158793 A

  A general UV ink contains a photopolymerization initiator (hereinafter also referred to as an initiator) as a catalyst. Then, when the UV ink is irradiated with UV, the initiator is activated, whereby polymerization of components such as monomers contained in the UV ink is started, and the ink is cured and fixed on the medium. Since this initiator has a yellowish color, the UV ink has a slight yellow component.

  In particular, this yellow tint is conspicuous when printing is performed using a transparent UV ink that does not contain a pigment component. For example, a transparent UV ink may be applied thickly on the image surface as an image glossiness adjustment or image coating material. In such a case, since the printed image looks yellowish due to the effect of the transparent ink, the image quality is likely to deteriorate. For this reason, it is difficult to print an image with good image quality by printing using transparent UV ink.

  An object of the present invention is to print an image with good image quality using a transparent UV ink.

The main invention for achieving the above object is to form a color image by ejecting a yellow ink and a color ink other than the yellow, and a clear ink containing a catalyst having a yellow component on the color image. A printing control apparatus that controls a printing apparatus that discharges to form a clear image, wherein each color gradation value and glossiness of red, green, and blue included in a first color space, and the above-mentioned included in a second color space A lookup table for associating the gradation values corresponding to the colors of the yellow ink, the non-yellow color ink, and the clear ink, and using the lookup table, the first color space The gradation value of each pixel constituting the color image and the glossiness of each pixel constituting the clear image are expressed in the second color space. When color conversion scale value to determine the tone value of the previous SL cleared in accordance with the glossiness, red included in the first color space, green, from the color tone values of the blue, the second color space A provisional gradation value of yellow included in the image is determined, and the provisional gradation value of yellow is decreased in accordance with the gradation of the yellow component included in the determined gradation value of clear. It is a printing control device.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

1 is a block diagram illustrating an overall configuration of a printer. FIG. 2 is a schematic side view illustrating a configuration of the printer 1. FIG. 2 is a diagram for explaining the arrangement of a plurality of short heads on the lower surface of the yellow head and the arrangement of nozzles of the short heads. It is a figure showing the flow of image printing operation | movement. It is a figure explaining how a color image looks when a clear image is formed on a color image. FIG. 6 is a schematic explanatory diagram of processing performed by a printer driver. It is a flowchart of the color conversion process of 1st Embodiment. It is a flowchart of the color conversion process of 2nd Embodiment.

  At least the following matters will become clear from the description of the present specification and the accompanying drawings.

A printing control apparatus that controls a printing apparatus that discharges yellow ink and color inks other than yellow to form a color image, and discharges clear ink containing a catalyst having a yellow component to form a clear image. Each of red, green, and blue color gradation values and glossiness included in the first color space, and the yellow ink, the non-yellow color ink, and the clear ink included in the second color space, respectively. A look-up table that associates the tone values corresponding to the colors of the image, and using the look-up table, the tone values of the respective pixels constituting the color image of the first color space and the clear image are obtained. When converting the glossiness of each of the pixels to the gradation value of the second color space, at least the glossiness is determined according to the glossiness To change the tone value of the rear and the gradation value of the yellow, print control apparatus, characterized in that.
According to such a printing control apparatus, it is possible to print an image with a good image quality using transparent UV ink in the printing apparatus.

In this printing control apparatus, it is preferable that the yellow gradation value is changed based on the determined clear gradation value after the clear gradation value is determined according to the glossiness. .
According to such a print control apparatus, the discharge amount of the clear ink and the discharge amount of the yellow ink are appropriately adjusted according to the magnitude of the glossiness of the clear image, and the yellowing of the image can be suppressed with high accuracy. I can do it.

In this printing control apparatus, it is desirable that the yellow gradation value in the pixel decreases as the clear gradation value in a pixel increases.
According to such a print control apparatus, even when the amount of clear ink ejected to a predetermined area increases (or decreases) according to the glossiness of the clear image, the entire color image and clear image in that area The yellow component is kept almost constant. Therefore, even when the clear image is formed thick, yellowing of the printed image can be made inconspicuous.

The print control apparatus includes a plurality of the lookup tables corresponding to the glossiness of the clear image, and uses the lookup table having a gloss smaller than the glossiness at the pixel position to be color-converted. The first color space in the pixel by interpolating using the second color space gradation value converted using the large glossy look-up table and the second color space gradation value. It is preferable that the color space gradation value is color-converted to the gradation value of the second color space.
According to such a printing control apparatus, it is possible to print a high-quality image in which yellowing is not noticeable while changing the glossiness to an arbitrary size.

In this printing control apparatus, it is preferable that the yellow ink and the clear ink are inks that are cured by being irradiated with light.
According to such a printing control apparatus, since it is possible to form a high-quality image in which yellowing is not noticeable, when printing is performed using a photocurable ink containing a yellowish reaction initiator. It is particularly effective.

In this printing control apparatus, it is preferable that the clear image is formed on the color image.
According to such a printing control apparatus, even when a clear image is formed on a color image, deterioration of the image quality of the color image when the clear image is seen is less noticeable.

  Also, a print control for controlling a printing apparatus that forms a color image by discharging yellow ink and a color ink other than yellow, and forms a clear image by discharging a clear ink containing a catalyst having a yellow component. A program for causing a device to perform color conversion processing, each of which includes red, green, and blue color gradation values and glossiness included in a first color space, the yellow ink included in a second color space, and the A lookup table is provided for associating tone values corresponding to the colors of the color ink other than yellow and the clear ink, and the color image of the first color space is configured using the lookup table. The gradation value of each pixel and the glossiness of each pixel constituting the clear image are changed to the gradation value of the second color space. When, in accordance with the glossiness, a program for executing a function of changing the gradation value of the yellow and gray scale values of at least the clear to the printing control device is apparent.

=== First Embodiment ===
<Basic configuration of printing apparatus>
As a form of a printing apparatus for carrying out the invention, an ink jet printer (printer 1) will be described as an example. The printer 1 is an image forming apparatus capable of forming (printing) an image on a medium by discharging a liquid (for example, ink) onto the medium such as paper, cloth, or a transparent film sheet. The liquid used for printing in the present embodiment is an ultraviolet curable ink (hereinafter also referred to as UV ink) that is cured by being irradiated with light (electromagnetic waves) such as ultraviolet light (hereinafter also referred to as UV). Details of the UV ink will be described later.

  The configuration of the printer 1 according to the first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a block diagram illustrating the overall configuration of the printer 1. FIG. 2 is a schematic side view showing the configuration of the printer 1.

  As shown in FIG. 1, the printer 1 is communicably connected to a computer 110 that is an external control device. A printer driver is installed in the computer 110. The printer driver will be described later.

  In order for the computer 110 to print an image on the printer 1, the print data converted from the image data according to the image to be printed is transmitted to the printer 1. The print data is data in a format that can be interpreted by the printer 1 and includes various command data and pixel data. The command data is data for instructing the printer 1 to execute a specific operation. This command data includes, for example, data such as command data indicating the transport amount of the printing medium. The pixel data is data related to pixels of an image to be printed.

  Here, a pixel is a unit element constituting an image, and an image is formed by arranging these pixels two-dimensionally. Pixel data in the print data is data (for example, gradation values) related to dots formed on the medium. The pixel data is composed of 2-bit data for each pixel. This 2-bit pixel data can represent one pixel in four gradations.

  The printer 1 includes a transport unit 10, a head unit 20, an irradiation unit 30, a detector group 50, and a controller 60 (see FIG. 1). The controller 60 controls each unit such as the transport unit 10 and the head unit 20 based on print data received from the computer 110 which is an external device, and prints an image on a medium. The situation in the printer 1 is monitored by the detector group 50, and the detector group 50 outputs the detection result to the controller 60. The controller 60 controls each unit based on the detection result output from the detector group 50.

<Transport unit 10>
The transport unit 10 is a medium transport unit that transports a medium (for example, a long film S wound in a roll shape) in a predetermined direction (hereinafter also referred to as a transport direction). The transport unit 10 includes an upstream transport roller 12A, a downstream transport roller 12B, and a transport drum 13 (see FIG. 2).

  When a transport motor (not shown) rotates, the upstream transport roller 12A and the downstream transport roller 12B rotate, and the transport drum 13 rotates. The film S along the peripheral surface of the transport drum 13 and pressed and supported by the upstream transport roller 12A and the downstream transport roller 12B is transported in the clockwise direction of FIG. 2 as the transport drum 13 rotates. That is, in the present embodiment, the conveyance direction of the medium is the rotation direction of the conveyance drum 13 (the direction of the circumferential surface of the drum). The medium transport speed (the rotational speed of the transport drum 13) by the transport unit 10 is controlled by the controller 60 so as to be a predetermined speed (almost constant speed).

  Outside the transport drum 13, a head unit 20 and an irradiation unit 30 are provided between the upstream transport roller 12 </ b> A and the downstream transport roller 12 </ b> B so as to face the peripheral surface of the transport drum. The film S transported by the rotation of the transport drum 13 is transported downstream in the transport direction while being printed in a printable region (region facing the head unit 20). That is, when the transport drum 13 transports the film S, the film S moves in the transport direction with respect to the head unit 20. The film S being transported is electrostatically attracted or vacuum attracted to the transport drum 13.

<Head unit 20>
The head unit 20 is a liquid ejection unit that ejects a liquid (UV ink in the present embodiment) onto the film S, and includes a plurality of heads (21 to 25) for each color of ink. The head unit 20 discharges UV ink onto the film S being conveyed, thereby forming UV ink dots on the film S and printing an image on the film S. The printer 1 of the present embodiment is a line printer, and the head unit 20 can form dots for the width of the film S at a time.

  In this embodiment, as shown in FIG. 2, the yellow head 21 that discharges yellow (Y) ink and the magenta (M) ink is discharged from the upstream side to the downstream side along the transport direction of the film S. There are provided color ink heads for each color, including a magenta head 22, a cyan head 23 for ejecting cyan (C) ink, and a black head 24 for ejecting black (K) ink. An image (color image) is formed by discharging each color ink of YMCK from these color ink heads. In addition to YMCK, a head that discharges UV ink of other colors such as white (W) may be provided, and an image may be printed using five or more colors of UV ink.

  On the downstream side in the transport direction of the black head 24, a clear head 25 that discharges transparent clear (CL) ink is provided so as to face the peripheral surface of the transport drum 13. The clear ink (CL) is an ink used for adjusting the glossiness of a printed image, protecting the surface of the image, improving the color developability of the color ink, and generally contains or does not contain a color material or a pigment. Is a small amount of transparent ink. In the present embodiment, a clear image is formed by applying clear ink on the color image formed by the color ink heads (21 to 24), and the glossiness of the color image is adjusted.

  In each head (21 to 25) of the head unit 20, a plurality of short heads are arranged in a staggered pattern along the width direction of the film S. FIG. 3 is a diagram illustrating the arrangement of a plurality of short heads on the lower surface of the yellow head 21 and the arrangement of the nozzles of the short heads. As shown in FIG. 3, the yellow head 21 is composed of three short heads 21A, 21B, and 21C. In each short head, a plurality of nozzles Nz are arranged at regular intervals (nozzle pitch) along the width direction of the film S. In the figure, the state in which the nozzles Nz are arranged in each head is indicated by two lines. By discharging yellow ink (Y) from the plurality of nozzles Nz, a plurality of yellow ink dots arranged in the width direction of the film S can be formed. Note that the number of short heads constituting one head is arbitrary, and four or more short heads may be used.

  Each nozzle Nz is provided with a drive element such as a piezo element. Then, when a drive signal generated by the controller 60 is applied to the drive element, the drive element is driven, and an ink droplet is ejected from the nozzle Nz. As a driving element other than the piezo element, for example, a heating element, an electrostatic actuator, or the like can be used.

  The other heads (22 to 25) other than the yellow head 21 have basically the same structure.

<Irradiation unit 30>
The irradiation unit 30 is an irradiation unit that irradiates light (UV) toward the ink landed on the film S. The UV ink dots formed on the film S are cured by receiving UV irradiation from the irradiation unit 30. In the printer 1, the irradiation unit 30 includes provisional curing irradiation units 31 to 34 that perform UV irradiation for temporary curing of UV ink, and a main curing irradiation unit 35 that performs UV irradiation for main curing. Two-stage curing is performed. Here, “temporary curing” is to cure the surface portion of the dots in order to suppress the flow of UV ink (dot spread) that has landed on the medium, or to prevent ink bleeding between dots. . Further, “main curing” is for completely curing the UV ink. Normally, the UV energy (UV irradiation amount) irradiated in “main curing” is larger than the UV energy (irradiation amount) irradiated in “temporary curing”.

The temporary curing irradiation units 31 to 34 are provided on the downstream side in the transport direction of the color ink heads 21 to 24, respectively (see FIG. 2), and temporarily cure the color ink dots formed by the upstream color ink heads. Irradiate UV to temporarily cure the dots. The temporary curing irradiation units 31 to 34 are each formed longer than the width of the film S to be printed. Further, a light emitting diode (LED) is used as a light source. The LED can easily change the irradiation energy by controlling the magnitude of the input current. The irradiation intensity of UV for temporary curing is, for example, about 10 to 100 mJ / cm ² .

The main curing irradiation unit 35 is provided on the downstream side in the transport direction of the clear head 25 (see FIG. 2), and is formed by the color image formed by the color ink heads 21 to 24 on the upstream side and the clear head 25. The clear image is irradiated with UV for main curing. Thereby, the color image printed on the medium (film S) and the clear image formed on the color image are fully cured. The main curing irradiation section 35 is formed longer than the width of the film S to be printed. Further, an LED or a lamp (metal halide lamp, mercury lamp, etc.) is used as a light source. The irradiation intensity of UV for main curing is, for example, about 1000 mJ / cm ² .

  A temporary curing irradiation unit (not shown) for temporarily curing the clear ink dots may be provided between the clear head 25 and the main curing irradiation unit 35.

<Detector group 50>
The detector group 50 is for monitoring the status of the printer 1. The detector group 50 includes a rotary encoder, an optical sensor, and the like (all not shown). The rotary encoder detects the amount of rotation of the upstream conveyance roller 12A and the downstream conveyance roller 12B (or the conveyance drum 13). The optical sensor detects the leading edge position of the film S (the position of the printing edge on the downstream side in the conveying direction), the trailing edge (the position of the printing edge on the upstream side in the conveying direction), and the like according to the situation.

<Controller 60>
The controller 60 controls the printer 1. The controller 60 includes an interface unit 61, a CPU 62, a memory 63, and a unit control circuit 64.

  The interface unit 61 transmits and receives data between the computer 110 that is an external device and the printer 1. The CPU 62 is an arithmetic processing device for performing overall control of the printer 1. The memory 63 is for securing an area for storing a program of the CPU 62, a work area, and the like, and is configured by a storage element such as a RAM or an EEPROM. The CPU 62 controls each unit such as the transport unit 10 and the head unit 20 via the unit control circuit 64 in accordance with a program stored in the memory 63.

<Overview of image printing operation>
An operation for printing an image using the printer 1 will be briefly described. FIG. 4 is a diagram illustrating the flow of the image printing operation.

  First, the glossiness of an image to be printed is set. The greater the glossiness is set, the more glossy images can be formed. For example, the glossiness is set in advance in a plurality of stages (for example, four stages of high gloss, medium gloss, low gloss, and low mat) in the printer driver, and the glossiness is set via a user interface (not shown). This is done by the user selecting a desired gloss level. A printer driver (installed in the computer 110 in this embodiment) generates print data from the set glossiness data and image data to be printed, and transmits the print data to the printer 1.

  When the printer 1 receives print data from the computer 110, a color image is printed using color ink (YMCK), and then a clear image is printed using clear ink (CL).

  The controller 60 of the printer 1 intermittently ejects each color ink (YMCK) while the medium passes through the area facing the head unit 20 while conveying the medium by rotating the conveyance drum 13 at a constant speed. To form dots. That is, the dot formation process and the medium transport process are performed simultaneously. As a result, a dot row composed of a plurality of UV ink dots along the medium width direction is formed on the medium, and an image (color image) is formed by arranging a plurality of dot rows in the transport direction. The formed dot rows are each irradiated with UV for temporary curing from the irradiation portion for temporary curing of the irradiation unit 30, and the color ink dots (YMCK) are temporarily cured.

  After a color image with color ink dots (YMCK) is formed, a clear image with clear ink dots (CL) is formed on the color image. The clear image forming operation is basically the same as the color image forming operation.

  Thereafter, UV for main curing is irradiated from the main curing irradiation unit 35 to the formed color image and clear image, and the ink dots are fixed by the main curing of the ink dots. As a result, a clear image is printed over the color image.

=== Characteristics of printing using UV ink ===
<Composition of UV ink>
First, the UV ink used for printing will be described. The UV ink is an ink containing an ultraviolet curable resin, and is cured by undergoing a photopolymerization reaction in the ultraviolet curable resin when irradiated with UV. The UV ink used in this embodiment contains a polymerizable compound, a catalyst such as a photopolymerization initiator, and other additives.

  A polymerizable compound is a compound capable of undergoing a polymerization reaction when irradiated with light. Specific examples of the polymerizable compound include various (meth) acrylate monomers, various (meth) acrylate oligomers, various vinyl monomers, various vinyl ether monomers, and the like.

  A photopolymerization initiator (hereinafter also referred to as an initiator) is a catalyst having a function of efficiently initiating polymerization of a polymerizable compound when irradiated with light. When the UV ink is irradiated with UV, the initiator is activated to form a reaction start point. Then, the reaction start point activates double bonds such as oligomers, the oligomers are bonded to each other, and finally the ink is changed from liquid to solid by polymerizing in a network.

  Further, the UV ink may contain additives such as a color material (pigment, dye, etc.), a solvent, a surfactant, a polymerization inhibitor, and a polymerization accelerator.

<About yellowing by clear UV ink>
Since the initiator contained in the UV ink usually has a yellow component, the UV ink often has a slight yellowish color. In the color (YMCK) UV ink, the yellow color of the initiator is not noticeable because the color material contained is dark. On the other hand, a clear (CL) UV ink that does not contain a coloring material may cause problems during printing because the yellow component of the initiator tends to be noticeable and does not become completely colorless and transparent.

  FIG. 5 is a diagram illustrating how a color image looks when a clear image is formed on the color image. The figure shows a case where a clear image is formed on a color image (shaded portion) formed on a medium as viewed from the side. The figure on the left is when the clear image is thinly formed (clear image thickness = h1), and the figure on the right is when the clear image is thick (clear image thickness = h2 (h1 <h2). ) And). A plurality of black circles shown in the clear image represents an initiator (catalyst) contained in the clear UV ink.

  When adjusting the glossiness of an image using clear UV ink, if the clear image is thinly formed, the amount of clear ink ejected per unit area is small, so it is included in the unit area. The amount of initiator is also reduced (the left figure in FIG. 5). In this case, since the yellow component is small, yellowing of the image is hardly noticeable.

  On the other hand, when printing an image with high glossiness, the amount of clear ink ejected per unit area increases in order to form a thick clear image. In this case, the amount of the initiator contained in the unit area is also increased (the diagram on the right side of FIG. 5). That is, the yellow component becomes dark and yellowing is easily noticeable. Therefore, the color image formed under the clear image looks strongly yellow when viewed through the clear image. As a result, the entire image is recognized as yellowish, and the image quality seems to deteriorate. In this specification, such a phenomenon that an image looks yellow with clear ink is called “yellowing” of the image.

<Method of eliminating yellowing>
As a method of eliminating the yellowing of the image, a method of adjusting the amount (discharge amount) of the yellow ink that forms the color image according to the amount of the yellow component contained in the clear ink that forms the clear image can be considered.

  The degree of yellowing is affected by the thickness of the clear image formed on the color image, as described with reference to FIG. That is, as the amount of clear ink ejected in a predetermined area increases, the amount of initiator present in that area increases, and the yellow component becomes darker and the degree of yellowing of the image increases. Therefore, the total amount of yellow components in the region is adjusted by reducing the amount of yellow ink discharged in that region by the amount that the yellow component has increased by the clear ink. That is, the gradation of yellow indicated by the original image data is reproduced by adjusting the ejection amounts of the clear ink (CL) and the yellow ink (Y).

  The discharge amount of the clear ink (CL) and the yellow ink (Y) is adjusted by changing each gradation value using the LUT in the color conversion process when the print data is generated from the image data by the printer driver. Is done.

=== Specific Description of Printing Process ===
Processing performed by the printer driver during image printing will be described.

<About the printer driver>
FIG. 6 is a schematic explanatory diagram of processing performed by the printer driver. The printer driver is a program that causes the computer 110 (corresponding to a print control apparatus in the present embodiment) to execute various processes.

  Computer programs such as an application program 114 and a printer driver 116 are installed on the computer 110. The application program 114 is an image editing program, for example. The user creates color image data to be printed and glossiness data representing the glossiness of a clear image formed on the color image by the application program 114, and gives an instruction to print the image. Upon receiving a print instruction, the application program 114 outputs image data and glossiness data to the printer driver 116.

  Since the printer driver 116 generates print data from the image data and glossiness data output from the application program 114, the resolution conversion process (S101), the color conversion process (S102), the halftone process (S103), and the rasterization process ( S104) is performed. Hereinafter, various processes performed by the printer driver 116 will be described.

  The resolution conversion process (S101) is a process for converting image data (text data, image data, etc.) into bitmap data of print resolution. The image data after the resolution conversion processing is assumed to be composed of 256-gradation RGB data (RGB color space image data) representing a color image and glossiness data representing the glossiness of the clear image.

  The color conversion process (S102) is a process for converting RGB data into YMCK data (image data in the YMCK color space) and converting glossiness data into CL data (image data represented by CL gradation values). is there. The YMCK data is data corresponding to the color ink color of the printer 1.

  In the present embodiment, a color space including data representing each color of red (R), green (G), and blue (B) and data representing the magnitude of glossiness is defined as a first color space. A color space including data representing each color of yellow (Y), magenta (M), cyan (C), black (K), and clear (CL) is defined as a second color space.

  In the color conversion process, the printer driver 116 refers to a table (look-up table LUT) in which RGB gradation values and glossiness in the first color space are associated with YMCK and CL gradation values in the second color space. Is done by doing. The data after the color conversion process is composed of 256 gradation YMCK data indicating a color image and 256 gradation CL data indicating a clear image. Details of the color conversion process will be described later.

  The halftone process (S103) is a process of converting high gradation number data into gradation number data that can be formed by the printer 1. Here, 256-gradation YMCK data is converted to 4-gradation YMCK data, and similarly, 256-gradation CL data is converted to 4-gradation CL data. In the halftone process, a dither method, a γ correction, an error diffusion method, or the like is used. The four gradations of YMCK data and CL data are dot data indicating dot formation (no dot, small dot, medium dot, large dot) of each pixel. Note that the data may be converted into data of two gradations indicating the presence or absence of dots instead of the four gradations.

  The rasterization process (S104) is a process for changing two-dimensional image data in the order of data to be transferred to the printer 1. The rasterized data is output to the printer 1 as pixel data included in the print data. The printer 1 ejects ink from each nozzle in accordance with dot data of four gradations, and forms dots (small dots, medium dots, or large dots) on each pixel on the medium.

<Color conversion processing>
FIG. 7 is a flowchart schematically illustrating the process performed in the color conversion process (S102) of the first embodiment.

  The image data before the color conversion process is data indicating a two-dimensional digital image. The digital image is configured by two-dimensionally arranging pixels, and pixel data indicating 256 gradations of RGB in the first color space and data L indicating glossiness are assigned to each pixel. . In the color conversion process, the data of the first color space is converted into the data of the second color space by using a lookup table (LUT) for each of the pixel data constituting the image data.

  Hereinafter, the image data of the first color space in a certain pixel is expressed as (R1, G1, B1, L1). Then, the image data in the second color space in the pixel after color conversion is described as (Y1, M1, C1, K1, CL1).

  First, the printer driver refers to a plurality of levels of glossiness set by the user at the start of printing for the position (target position) of a pixel subject to color conversion processing (S121). The data representing the glossiness is represented as L1 as described above. Normally, the glossiness is set so that the entire image has a uniform glossiness, and therefore glossiness data is assigned to L1 for all pixels. However, it is possible to set different glossiness for each region.

  It should be noted that the glossiness can be set to zero. In this case, the discharge amount of the clear ink (CL) becomes zero, and a clear image is not formed on the color image.

  Using the above-described LUT, the printer driver converts the gloss level data L1 at the target position into a clear gradation value (CL1), and determines the clear (CL) gradation value (S122). Since the thickness of the clear image to be formed in that portion is determined according to the magnitude of the glossiness, the discharge amount of the clear ink (CL) necessary for forming the clear image is also determined. The discharge amount of the clear ink is adjusted by the clear gradation value set in the LUT. That is, by using the LUT, it is possible to determine the clear gradation value CL1 corresponding to the glossiness data L1.

  After the clear gradation value (CL1) is determined, the color gradation value is converted from the RGB gradation value to the YMCK gradation value. First, the tone value represented by (R1, G1, B1) in the first color space is converted to the color tone value to (Y ′, M1, C1, K1) in the second color space (S123). .

  Here, the yellow tone value Y ′ is not the final tone value Y1 corresponding to the actual ejection amount of the yellow ink (Y). In the conventional color conversion, the gradation value of each color of YMCK is determined as it is by converting the data in the RGB color space into the data in the YMCK color space. The size of Y ′ is changed (adjusted) according to the gradation value. That is, it can be said that the yellow gradation value Y ′ in S123 is a provisional gradation value.

  Finally, the actual gradation value (Y1) of yellow is calculated from the temporary gradation value (Y ′) of yellow and the clear gradation value (CL1), and the gradation value of yellow (Y) is determined. (S124).

When the tone of the yellow component included in the clear ink represented by a gray level value CL1 and CL1 _Y, minute yellow component corresponding to the CL1 _Y causes yellowing of the image. Therefore, when forming a color image, CL1 _Y is subtracted from the temporary gradation value _Y ′ of yellow ink, and the actual gradation value of yellow is determined as Y1 = Y′−CL1 _Y. That is, the total yellow component in the area is represented by the sum of the yellow component of the color image and the yellow component of the clear image in a certain area.

  In the present embodiment, the series of processing (color conversion processing) in S102 is efficiently performed using an LUT.

Note that the yellow gradation CL1 _Y when the clear gradation value is CL1 may be experimentally obtained in advance. For example, a clear image is printed at a plurality of gloss levels (a plurality of gradations) using a clear ink used in actual printing. Then, by colorimetry each clear image, previously obtained relation between CL1 and CL1 _Y. In addition, a coefficient k such that CL1 _Y = CL1 × k may be set from the relationship thus obtained, and CL1 _Y may be calculated by calculation.

Further, the this case CL1 and CL1 _Y, nearly so can be considered proportional to, the larger the gradation value CL1 clear, relationship gradation value Y1 of yellow decreases is established. That is, even when the same color image is printed, the thicker the clear image formed on the color image, the smaller the amount of yellow ink ejected to form the color image. Therefore, even when the clear image is formed thick, yellowing of the image can be made inconspicuous.

<Effects of First Embodiment>
In the first embodiment, the printer driver performs red, green, and blue color gradation values (R1, G1, B1) and glossiness (L1) included in the first color space, and a clear color included in the second color space. The color conversion process is performed using a look-up table that associates the tone value (CL1), the tone value (Y1) of yellow, and the tone values (M1, C1, K1) of other colors. At this time, at least the clear gradation value and the yellow gradation value are changed according to the glossiness of the clear image to be formed. Thereby, even when a clear image is formed on a color image, yellowing of the image can be made inconspicuous and an image with good image quality can be printed.

=== Second Embodiment ===
In the first embodiment, an image is printed by the user selecting a desired gloss level from a plurality of gloss levels set in advance. In the second embodiment, a case will be described in which the glossiness of a print image is set to an arbitrary value by the user.

A printing apparatus for carrying out the second embodiment is a printing apparatus similar to the printer 1 described above.
The flow of the printing operation of the second embodiment is basically the same as that of the first embodiment (see FIG. 4). However, the glossiness setting is different in that the user can set any glossiness between 0% and 100%. The gloss level is set via a user interface (not shown). Here, it is assumed that a clear image is not formed when the gloss level is set to 0%, and a clear image corresponding to “high gloss” in the first embodiment is formed when the gloss level is set to 100%. Do.

<Color Conversion Processing of Second Embodiment>
In the printing process performed by the printer driver in the second embodiment, the processing operation in the color conversion process (S102 in FIG. 6) is different from that in the first embodiment.
In the second embodiment, the printer driver uses six look-up table LUTs corresponding to the glossiness of a clear image (LUTs corresponding to glossiness 0%, 20%, 40%, 60%, 80%, and 100%). I have. As described in the first embodiment, each LUT uses the (R, G, B) gradation value and the gloss level (L) of the first color space as the (Y, M) of the second color space. , C, K, CL). Note that the number of LUTs provided in the printer driver is not limited to six.

FIG. 8 is a flowchart of color conversion processing according to the second embodiment.
First, the printer driver refers to the gloss level set by the user at the start of printing for the position (target position) of the pixel subject to color conversion processing (S221). Here, description will be made assuming that glossiness = X%.

  Next, the printer driver searches a look-up table (glossiness A% LUT) corresponding to a glossiness lower than the glossiness referenced in S221 and a look-up table (glossiness B%) corresponding to a high glossiness. The two LUTs are selected (S222). For example, when the glossiness X = 65%, the LUT corresponding to the glossiness 60% and the LUT corresponding to the glossiness 80% are selected.

Next, the printer driver performs clear (CL) gradation value conversion using the two LUTs selected in S222 (S223A, S223B). Here, glossiness X% is converted to a clear gradation value (CL1A) using glossiness A% LUT, and glossiness X% is converted to a clear gradation value (CL1B) using glossiness B% LUT. Converted.

  Next, the printer driver calculates a weight α (S224). The weight α corresponds to the ratio of the glossiness difference between the glossiness X% and the glossiness A% to the glossiness difference corresponding to the two LUTs selected in S222. In the above example, α = (X−A) / (BA) = (65−60) / (80−60) = 0.25.

Next, the printer driver uses the two clear gradation values CL1A and CL1B calculated in S223 and S224 and the weight α calculated in S224 to perform the interpolation of the clear gradation value as in the following equation. (S225), a clear gradation value CL1 is determined.
(CL1) = (1-α) × (CL1A) + α × (CL1B)

  After the clear gradation value is determined, the color gradation value is converted. First, the color gradation value is converted using the glossiness A% LUT (S226A). Here, the data (R1, G1, B1) in the first color space is converted into data (Y′A, M1A, C1A, K1A) in the second color space. Similarly, the color gradation value is converted using the glossiness B% LUT (S226B), and the data of (R1, G1, B1) is converted to (Y′B, M1B, C1B, K1B). Then, color tone values are interpolated using the weight α in the same manner as the above-described interpolation (S227), and color tone values (Y ′, M1, C1, K1) are calculated.

  Finally, as in S124 of the first embodiment, the yellow tone value is determined using the clear tone value CL1 and the yellow provisional tone value Y ′ (S228). A gradation value Y1 is determined.

<Effects of Second Embodiment>
In the second embodiment, color conversion processing is performed by performing interpolation using a plurality of LUTs to print a color image and a clear image. As a result, it is possible to form an image with good image quality that is less noticeable of yellowing while adjusting the glossiness of the clear image to be formed to a desired size.

=== Other Embodiments ===
Although the printer and its control device as one embodiment have been described, the above embodiment is for facilitating the understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About printing devices>
In the above-described embodiment, the printing apparatus that discharges ink while transporting the medium by rotating the transport drum has been described. However, the present invention is not limited to this. For example, a printing device that performs printing while transporting a medium in a plane, or a so-called serial type that performs printing by alternately repeating the operation of transporting a medium and the operation of ejecting ink while moving a head. It may be a printing device.

<About the head unit 20>
In the above-described embodiment, an example of printing an image using four color inks of YMCK and clear (CL) ink has been described. However, the present invention is not limited to this. For example, printing may be performed using inks of other colors such as light cyan (LC), light magenta (LM), and white (W).

  The arrangement of the color ink heads in the head unit 20 is arranged in the order of YMCK from the upstream side in the transport direction, but is not limited to this. For example, the order of the arrangement of the yellow head (Y) and the magenta head (M) may be switched, or two black heads (K) are arranged. It is good also as a different structure from a head.

<About the printer driver>
In each of the above-described embodiments, the printer driver processing is performed by the computer 110 (PC). However, the printer driver may be installed in the controller 60 of the printer 1 and the printer driver processing may be performed by the printer itself. In this case, the printer 1 has a built-in print control device.

1 Printer 10 transport unit, 12A upstream transport roller, 12B downstream transport roller,
13 Conveying drum,
20 head units, 21 yellow heads, 22 magenta heads,
23 Cyan head, 24 Black head, 25 Clear head 30 Irradiation unit, 31-34 Temporary curing irradiation unit, 35 Curing irradiation unit,
50 detector groups,
60 controller, 61 interface, 62 CPU, 63 memory,
64 unit control circuit,
110 computers,
114 application programs, 116 printer drivers,
S film

Claims (5)

A printing apparatus for forming a color image by discharging yellow ink and a color ink other than yellow, and forming a clear image by discharging a clear ink containing a catalyst having a yellow component onto the color image A printing control device for controlling,
The color gradation values and glossiness of red, green, and blue included in the first color space, and the yellow ink, the color ink other than yellow, and the clear ink included in the second color space, respectively. It has a lookup table that correlates the corresponding gradation values,
Using the look-up table, the gradation value of each pixel constituting the color image in the first color space and the glossiness of each pixel constituting the clear image can be calculated in the second color space. When converting colors to key values,
Determining the gray scale value before Symbol cleared in accordance with the glossiness,
A temporary gradation value of yellow included in the second color space is determined from each color gradation value of red, green, and blue included in the one color space;
The print control apparatus , wherein the yellow provisional gradation value is decreased according to the gradation of the yellow component included in the determined gradation value of the clear . The print control apparatus according to claim 1 ,
The printing control apparatus according to claim 1, wherein the yellow gradation value in the pixel decreases as the clear gradation value in a pixel increases. The print control apparatus according to claim 1 or 2 ,
A plurality of lookup tables according to the glossiness of the clear image;
Converted using the gradation value of the second color space converted using the look-up table having a gloss smaller than the gloss at the pixel conversion target position and the look-up table having a large gloss By interpolating with the gradation values of the second color space,
A print control apparatus, wherein the gradation value of the first color space in the pixel is color-converted to the gradation value of the second color space. The print control apparatus according to any one of claims 1 to 3 ,
The printing control apparatus according to claim 1, wherein the yellow ink and the clear ink are inks that are cured by being irradiated with light. A printing apparatus for forming a color image by discharging yellow ink and a color ink other than yellow, and forming a clear image by discharging a clear ink containing a catalyst having a yellow component onto the color image A program for causing a printing control apparatus to control to execute color conversion processing,
The color gradation values and glossiness of red, green, and blue included in the first color space, and the yellow ink, the color ink other than yellow, and the clear ink included in the second color space, respectively. It has a lookup table that correlates the corresponding gradation values,
Using the look-up table, the gradation value of each pixel constituting the color image in the first color space and the glossiness of each pixel constituting the clear image can be calculated in the second color space. When converting colors to key values,
Determining the gray scale value before Symbol cleared in accordance with the glossiness,
A temporary gradation value of yellow included in the second color space is determined from each color gradation value of red, green, and blue included in the one color space;
A program for causing the printing control apparatus to execute a function of decreasing the yellow temporary gradation value according to the gradation of the yellow component included in the determined clear gradation value .

Images