Abstract:
A printing apparatus, a printing method, an application program and a printing medium are disclosed. The printing apparatus is coupled to a control circuit which with the help of the application program, controls the operation of the printing apparatus. The printing apparatus contains at least two kinds of glossy recording materials with different concentrations. The printing apparatus performs glossy printing on a printing medium by controlling the usage of the two kinds of glossy recording materials.

Description:
[0001]    This application claims priority to Japanese Patent Application No. 2008-219135, filed Aug. 28, 2008, the entirety of which is incorporated by reference herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to a technology of printing an image by using recording materials including special glossy material with special gloss. 
         [0004]    2. Related Art 
         [0005]    According to the related art, after a background layer is formed on a print medium, printing is additionally performed on the background layer (for example, see JP-A-2002-530229). Such a method may be used for various printing methods. For example, in relation to an ink jet printer, after a metallic ink layer is formed on a print medium, color ink is printed on the metallic ink layer, so that metallic color with various hues can be produced. 
         [0006]    However, when printing metallic color while restricting the special glossy effect by a certain degree, the amount of metallic ink used must be reduced. In such a case, dots of the metallic ink are visible, so a decrease in the graininess of a printed image may become a problem. Such a problem occurs not just in the ink jet printer but in various printing apparatuses. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    An advantage of some aspects of the invention is to effectively print metallic color while allowing a special glossy effect to be compatible with fine granularity in a printed image. 
         [0008]    One embodiment of the invention is directed to a printing apparatus for performing printing by using a plurality of glossy recording materials, the printing apparatus comprising a carriage coupled to a print head having a plurality of ejection heads, wherein the carriage is further coupled to at least one cartridge coupled to the plurality of ejection heads, wherein the cartridge contains at least two kinds of glossy recording materials having different concentrations; a control circuit couple to the carriage and the plurality of ejection heads, and configured to control the plurality of ejection heads to perform printing, using at least one of the two kinds of glossy recording materials; and wherein the control unit is further configured to control a degree of desired special glossy effect by controlling a usage of the at least two kinds of glossy recording materials. 
         [0009]    In one aspect, the at least two kinds of glossy recording materials are comprised of a low-concentration glossy recording material and a high-concentration glossy recording material. 
         [0010]    In another aspect, when the degree of desired special glossy effect is increased, the control unit performs the printing by decreasing the usage of low-concentration glossy recording material while increasing the usage of high-concentration glossy recording material. 
         [0011]    In another aspect, when the degree of desired special glossy effect corresponds to an index less than or equal to a maximum achievable degree of gloss of the low-concentration glossy recording material, the control unit performs the printing by primarily using the low-concentration glossy recording material. 
         [0012]    In another aspect, the at least two kind of glossy recording materials have reflection angle dependence after being printed on a surface of a print medium. 
         [0013]    In another aspect, the control unit is capable of adjusting the special glossy effect by changing the usage of the high-concentration glossy recording material while maintaining the usage of the low-concentration glossy material at a constant level. 
         [0014]    In another aspect, the at least two kinds of glossy recording materials have reflection angle dependence after being printed on a surface of a print medium. 
         [0015]    In another aspect the at least two kinds of glossy recording materials include metal pigments, and wherein the metal pigments in one kind of glossy recording material have a density that is different from a density of another kind of glossy recording material. 
         [0016]    Another embodiment is directed to a method for performing printing by using a plurality of glossy recording materials, the method comprising: using a control unit, performing printing by filling at least a part of a print area of a print medium with dots formed by using at least two kinds of glossy recording materials having different concentrations; and using the control unit, controlling a degree of desired special glossy effect on the print area of the print medium by controlling a usage of at least two kinds of glossy recording materials. 
         [0017]    Another embodiment is directed to an application program on a computer system coupled to a printing apparatus, for controlling the operation of the printing apparatus to perform printing by using a plurality of glossy recording materials including a low-concentration glossy recording material and a high-concentration glossy recording material, the application program causing the computer system to execute using a control unit, printing by filling at least a part of a print area of a print medium with dots formed by using the plurality of glossy recording materials having different concentrations; and using the control unit, controlling a degree of desired special glossy effect on the print area of the print medium by controlling a usage of the plurality of glossy recording materials. 
         [0018]    Another embodiment is directed to a printed product printed by a plurality of glossy recording materials including a low-concentration glossy recording material and a high-concentration glossy material, the printed product including a print area of a print medium, at least part of which is filled with dots formed by using at the low-concentration glossy recording material and the high-concentration glossy material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
           [0020]      FIG. 1  is a block diagram schematically showing a configuration of a printing system according to an embodiment of the invention. 
           [0021]      FIG. 2  is a block diagram showing a configuration of a computer serving as a printing control apparatus. 
           [0022]      FIG. 3  is a block diagram showing a configuration of a printer. 
           [0023]      FIG. 4  is a graph showing the difference of characteristics of the glossiness of a printed product due to difference densities of metal pigment in metallic ink. 
           [0024]      FIG. 5  is a flowchart showing a printing process. 
           [0025]      FIG. 6  is a graph showing a method of determining the usage amounts of low density metallic ink and high density metallic ink. 
           [0026]      FIG. 7  is a graph showing a method of determining the usage amounts of low density metallic ink and high density metallic ink according to a modification. 
           [0027]      FIG. 8  is a graph showing a method of determining the usage amounts of low density metallic ink and high density metallic ink according to a modification. 
           [0028]      FIG. 9  is a graph showing a difference of characteristics of an index value regarding a special glossy effect of a printed product, which is caused by a difference of metal pigment in metallic ink. 
           [0029]      FIG. 10  is a graph showing a difference of characteristics of an index value regarding a special glossy effect of a printed product, which is caused by a difference of metal pigment in metallic ink. 
       
    
    
     DETAILED DESCRIPTION 
     A. Outline of a Printing System 
       [0030]      FIG. 1  is a block diagram schematically showing a printing system  10  according to an embodiment of the invention. As shown in  FIG. 1 , the printing system  10  includes a computer  100  serving as a printing control apparatus, and a printer  200  that prints an image under the control of the computer  100 . The printing system  10  may serve as a printing apparatus in a broad sense by allowing all elements thereof to be integrally formed with each other. 
         [0031]    The printer  200  according to the embodiment has Cyan ink, Magenta ink, Yellow ink and Black ink as color ink, and metallic ink. The metallic ink allows a special glossy effect to be produced on a printed product, and detailed description thereof will be given later. According to an embodiment, the color ink includes the black ink. 
         [0032]    The computer  100  includes a predetermined operating system installed therein, and an application program  20  executed under the control of the operating system. The operating system has a video driver  22  and a printer driver  24 . For example, if image data ORG is received from a digital camera  120  through a peripheral device interface  108 , the application program  20  displays an image, which is represented by the image data ORG, on a display  114  through the video driver  22 . Further, the application program  20  outputs the image data ORG to the printer  200  through the printer driver  24 . The image data ORG, which is sent to the application program  20  from the digital camera  120 , includes the three primary colors of red R, green G and blue B. 
         [0033]    The application program  20  according to an embodiment, can designate a region (hereinafter, referred to as a color region), which is filled with the three primary colors of R, G and B, and a region (hereinafter, referred to as a metallic region), which is filed with metallic color, in an arbitrary region of the image data ORG The metallic region may overlap the color region. More specifically, the two regions may be designated such that a color image is formed with the metallic color used as a background color. Further, the application program  20  can designate the level of an index regarding the special glossy effect. That is, the degree of the special glossy effect of the metallic region can be designated and controlled. The index regarding the special glossy effect will be described in detail later. 
         [0034]    The printer driver  24  includes a color conversion module  42 , a halftone module  44  and a print control module  46 . The print control module  46  includes a metallic dot formation module  47  and a color print module  48 . 
         [0035]    The color conversion module  42  converts RGB color components of the color region of the image data ORG into color components, such as Cyan C, Magenta M, Yellow Y and Black K, which can be expressed through the printer  200 , with reference to a prepared color conversion table LUT. 
         [0036]    The halftone module  44  performs halftone processing relative to the color-converted image data by the color conversion module  42 , such that the gray scale of the image data is represented by a distribution of dots. In one embodiment, the well-known ordered dither method may be used for the halftone processing. In another embodiment, other half tone processing may be used. Further, in addition to the half tone processing method, an error diffusion method, and a tone production method by density pattern and a halftone technology may be used for the halftone processing. 
         [0037]    The print control module  46  rearranges the halftone-processed image data in a sequence by which the image data is transmitted to the printer  200 , and outputs the rearranged data to the printer  200  as print data. Further, the print control module  46  controls the printer  200  by outputting various commands such as a print start command or a print end command to the printer  200 . 
         [0038]    According to an embodiment, the print control module  46  includes the metallic dot formation module  47  and the color print module  48 . The metallic dot formation module  47  forms metallic ink dots on the metallic region designated by the application program  20 , and the color print module  48  forms color ink dots with respect to the halftone-processed image, that is, the image of the color region. 
       B. Apparatus Configuration 
       [0039]      FIG. 2  is a block diagram showing a configuration of the computer  100  serving as the printing control apparatus. The computer  100  is generally known in the art and includes a CPU  102 , a ROM  104 , a RAM  106  and the like, which are connected with each other through a bus  116 . 
         [0040]    The computer  100  includes a disk controller  109  for reading data from a flexible disk  124 , a compact disk  126  and the like, a peripheral device interface  108  for transmitting and receiving data to and from a peripheral device, and a video interface  112  for driving a display  114 . The peripheral device interface  108  is connected to the printer  200  and a hard disk  118 . Further, if the digital camera  120  or a color scanner  122  is connected to the peripheral device interface  108 , image processing can be performed relative to images obtained through the digital camera  120  or the color scanner  122 . Further, if a network interface card  110  is installed at the computer  100 , the computer  100  can read data stored in a memory device  310  through a communication line  300 . If image data to be printed is obtained, the computer  100  prints the image data by controlling the printer  200  through the functions of the printer driver  24 . 
         [0041]    Hereinafter, the configuration of the printer  200  will be described with reference to  FIG. 3 . As shown in  FIG. 3 , the printer  200  includes a mechanism that transfers a print medium P using a sheet transfer motor  235 , a mechanism that allows a carriage  240  to reciprocate in an axial direction of a platen  236  using a carriage motor  230 , a mechanism that drives a print head  241  mounted on the carriage  240  to eject ink and form dots, and a control circuit  260  that controls signal exchange among the sheet transfer motor  235 , the carriage motor  230 , the print head  241  and a manipulation panel  256 . 
         [0042]    The mechanism, which allows the carriage  240  to reciprocate in the axial direction of the platen  236 , includes a sliding shaft  233 , which is installed in parallel to a shaft of the platen  236  such that the carriage  240  slidably moves, a driving belt  231  extending between a pulley  232  and the carriage motor  230 , and a position sensor  234  that detects the original position of the carriage  240 . 
         [0043]    The carriage  240  includes a color ink cartridge  243  that stores the color inks such as Cyan ink C, Magenta ink M, Yellow ink Y and Black ink K. Further, the carriage  240  includes metallic ink cartridges  242  that each store two kinds of metallic inks S 1  and S 2 . The print head  241  provided at a lower portion of the carriage  240  includes ink ejection heads  244  to  247  corresponding to the four kinds of the color inks, and ink ejection heads  248  and  249  corresponding to the two kinds of the metallic inks. The ink cartridges  242  and  243  are installed in the carriage  240  from the top to the bottom, so the inks can be supplied to the ejection heads  244  to  249  from the cartridges  242  and  243 . 
         [0044]    The control circuit  260  of the printer  200  includes the CPU, the ROM, the RAM, the peripheral device interface and the like, which are connected with each other through the bus. The control circuit  260  controls main scanning and sub-scanning operations of the carriage  240  by controlling operations of the carriage motor  230  and the sheet transfer motor  235 . Further, if the print data is received from the computer  100  through the PIF, the control circuit  260  drives the ink ejection heads  244  to  249  by supplying driving signals corresponding to the print data to the ink ejection heads  244  to  249  in correspondence with the main scanning and sub-scanning operations of the carriage  240 . 
         [0045]    The printer  200  having the hardware configuration as described above drives the carriage motor  230  to allow the ink ejection heads  244  to  249  to reciprocate relative to the print medium P in the main scanning direction. Further, the printer  200  drives the sheet transfer motor  235  to move the print medium P in the sub-scanning direction. The control circuit  260  forms ink dots of appropriate colors at appropriate positions on the print medium P by driving the nozzles at proper times based on the print data corresponding to the reciprocation (main scanning) of the carriage  240  and the movement (sub-scanning) of the print medium P. In this way, the printer  200  can print a color image on the print medium P. In one embodiment, the metallic ink is contained in the detachable cartridge installed in the printer  200 . However, in another embodiment the metallic ink may be contained in an ink tank provided separately from the printer  200 , and the ink tank may be connected with the printer  200 . In yet another embodiment, the metallic ink may be contained in a container integrally formed with the printer  200 . 
       C. Characteristics of Metallic Ink 
       [0046]    As described above, in one embodiment the printer  200  in the embodiment has the metallic ink cartridge  242  that receives the two kinds of the metallic inks S 1  and S 2 . The metallic ink allows the special glossy effect to be produced on the printed product. For example, the metallic ink may use an oil-based ink composition including metal pigments, organic solvents and resins to produce the metallic effect. In order to effectively obtain a metallic effect, in one embodiment the metal pigment includes flat plate-shaped particles. When the flat plate-shaped particle has a long diameter of X, a short diameter of Y and a thickness of Z in a plane, it is preferable that a 50% average particle diameter R50 of the particle is 0.5 μm to 3 μm, which corresponds to a diameter of a circle calculated from an area of the X-Y plane of the flat plate-shaped particles. In this embodiment, it is also preferred that a formula R50/Z&gt;5 is satisfied. For example, the metal pigment may be formed using aluminum or an aluminum alloy and may also be formed by crushing a metal deposition film. The metal pigment included in the metallic ink may have a density of about 0.1 weight % to about 10.0 weight %. However, the metallic ink is not limited to the above composition. That is, the metallic ink may employ various compositions if the metallic ink includes special glossy material with special gloss. Further, the metallic ink has optical properties such as reflection angle dependence after the metallic ink is printed on the surface of the print medium, so the metallic ink has various appearances corresponding to different observation angles. 
         [0047]    Further, the two kinds of the metallic inks used for the embodiment include metal pigments having densities different from each other. In one embodiment, the metallic ink including the metal pigment having a relatively high density will be referred to as high density metallic ink, and the metallic ink including the metal pigment having a relatively low density will be referred to as low density metallic ink. In one embodiment, the low density metallic ink S 1  has a composition of aluminum pigment of 0.5 weight %, glycerin of 20 weight %, triethyleneglycol monobutyl ether of 40 weight %, and BYK-UV3500 of 0.1 weight % (manufactured by BYK Chemie of Japan). The high density metallic ink S 2  has a composition of the aluminum pigment of about 1.5 weight %, the glycerin of about 20 weight %, the triethyleneglycol monobutyl ether of about 40 weight %, and the BYK-UV3500 of about 0.1 weight %. 
         [0048]    Hereinafter, the difference in characteristics between the low density metallic ink S 1  and the high density metallic ink S 2  will be described with reference to  FIG. 4 .  FIG. 4  is a graph showing the glossiness (incidence angle is 20°) of a printed product as a function of a duty, which represents a ratio of dots occupied in a print region, when performing printing by using the low density metallic ink S 1  and the high density metallic ink S 2 . As shown in  FIG. 4 , in the case of using the low density metallic ink S 1 , as the duty is increased from zero, the glossiness is increased. When the duty has a value of D 1 , the glossiness reaches the maximum value B 1 max (about 200) of the low density ink. Then, as the duty is increased more, the glossiness is significantly reduced. In the case of using the high density metallic ink S 2 , as the duty is increased from zero, the glossiness is increased with a higher slope as compared with the case of using the low density metallic ink S 1 . When the duty has the value of D 1 , the glossiness reaches the maximum value B 2 max (about 500) of the high density ink. Then, as the duty is increased more, the glossiness is slightly reduced. As described above, there is a large difference in the glossiness of the printed product depending on the amount of the metal pigment included in the metallic inks S 1  and S 2 . 
         [0049]    Further, the glossiness may be represented by one index regarding the special glossy effect of the metallic region. There are exceptions, but the special glossy effect is increased as the glossiness is increased. That is, as it can be seen from  FIG. 4 , the special glossy effect is increased using the metallic ink including the metal pigment with the high density and significantly varies depending on the duty, as compared with the case of using the metallic ink including the metal pigment with the low density. In this regard, when printing using the metallic ink including the metal pigment with the high density, the special glossy effect can be significantly increased. However, when performing printing in which the special glossy effect is restricted, the duty is reduced and the dots of the metallic ink are visible, so the fine granularity of the printed image may be reduced. When printing using the metallic ink including the metal pigment with the low density, the special glossy effect cannot be significantly increased. However, when performing printing in which the special glossy effect is restricted, the dots of the metallic ink are not easily visible and the duty is relatively large, so the fine granularity of the printed image may be improved. 
       D. Printing Process 
       [0050]    Hereinafter, the printing process performed by the printer driver  24  under the control of the computer  100  will be described.  FIG. 5  is a flowchart showing the printing process according to one embodiment. If the printing process starts, the computer  100  receives image data including the color region and the metallic region from the application program  20  through the printer driver  24  (Step S 100 ). In addition, the computer  100  receives an index value regarding the special glossy effect of the metallic region. The received index value may be set in advance, or may be selected by a user through the application program  20 . According to one embodiment, the index value represents the glossiness. For example, the computer  100  receives an input with the glossiness having a value of 300. In another embodiment, the computer  100  may receive a ratio with respect to the maximum value of the index value or a gray scale number representing the degree of the special glossy effect, instead of the index value. 
         [0051]    After the image data is received, the computer  100  converts the RGB image data to CMYK image data with respect to the color region of the image data (Step S 1102 ). After the CMYK image data is obtained, the computer  100  performs halftone processing by using the halftone module  44  to generate data which can be transmitted to the printer  200  (Step S 104 ). After the halftone processing, the computer  100  prints the metallic region included in the image data, which is received in Step S 100 , by controlling the printer  200  through the metallic dot formation module  47  (Step S 106 ). If the metallic region is completely printed, the computer  100  controls the printer  200  through the color print module  48  so that the halftone-processed color region is printed (Step S 108 ). 
         [0052]    The printing process will be described in detail with reference to  FIG. 6 .  FIG. 6  is a graph showing the amount of the low density metallic ink S 1  and the high density metallic ink S 2  which are used for printing the metallic region. As shown in  FIG. 6 , when the desired glossiness received in Step S 100  is equal to or less than the maximum gloss value B 1 max of the low density ink, the computer  100  performs printing by using only the low density metallic ink S 1  corresponding to the received glossiness. When the desired glossiness received in Step S 100  corresponds to the maximum gloss value B 1 max of the low density ink, the amount of the low density metallic ink S 1  used corresponds to the duty D 1  shown in  FIG. 4 . 
         [0053]    Further, when the desired glossiness received in Step S 100  is larger than the maximum gloss value B 1 max of the low density ink, the computer  100  performs printing by using the low density metallic ink S 1  and the high density metallic ink S 2 . More specifically, as the degree of desired glossiness received in Step S 100  is increased, the amount of the low density metallic ink S 1  used is reduced and the amount the high density metallic ink S 2  used is increased. In the event when the degree of desired glossiness received in Step S 100  corresponds to the maximum gloss value B 2 max of the high density ink, the amount of the high density metallic ink S 2  used corresponds to the duty D 1  and the amount of the low density metallic ink S 1  used is zero. 
         [0054]    The amount of the ink used may be easily determined by using a table in which the index value regarding the special glossy effect corresponds to the usage amounts of the low density metallic ink S 1  and the high density metallic ink S 2 . Further, the arrangement of dots formed by the low density metallic ink S 1  and dots formed by the high density metallic ink S 2  may be determined by the combination of the usage amounts of the low density metallic ink S 1 , the high density metallic ink S 2 , and a distribution of the two kinds of dots. 
         [0055]    In one embodiment, when the desired glossiness is equal to or larger than the maximum gloss value B 1 max of the low density ink is received, the duty of the low density metallic ink S 1  and the high density metallic ink S 2  is equal to the constant duty D 1  through the sum of the two duties. However, the embodiments of the invention are not limited thereto. That is, the duty may not necessarily be constant. For example, the duty may be increased as the desired glossiness is increased. Further, when the desired glossiness is equal to or less than the maximum gloss value B 1 max of the low density ink, even though the high density metallic ink S 2  is used at the same time, no problem occurs if the low density metallic ink S 1  is mainly used. 
         [0056]    When performing the printing within the range of the index regarding the special glossy effect, the desired degree of glossiness may not be obtained by using the low density metallic ink S 1 , by which the fine granularity of the printed image may be easily ensured. In such a case, the metallic region is printed by combining the low density metallic ink S 1  and the high density metallic ink S 2 . At this time, as the received index regarding the special glossy effect is increased, the amount of the low density metallic ink S 1  used is reduced and the use amount of the high density metallic ink S 2  is increased. More specifically, when performing printing in which the special glossy effect is restricted, the duty of the high density metallic ink S 2  is reduced. In this situation, the desired graininess of the printed image may not be achieved. However, as the special glossy effect is increased, the duty of the high density metallic ink S 2  is increased, so the graininess of the printed image does not matter. Thus, as the required special glossy effect is reduced, printing is performed by mainly using the low density metallic ink S 1  by which the fine granularity may be easily ensured. Further, as the required special glossy effect is increased, printing is performed mainly using the high density metallic ink S 2  having a large special glossy effect. Consequently, the metallic color can be properly printed while preventing the fine granularity of the printed image from being reduced. 
         [0057]    When performing the printing within the range of the index regarding the special glossy effect which can be obtained using the low density metallic ink S 1  by which the fine granularity of the printed image may be easily ensured, only the low density metallic ink S 1  is used. Thus, the metallic color can be properly printed while ensuring the fine granularity of the printed image. 
         [0058]    In one embodiment, the maximum gloss value B 1 max of the low density ink is employed as a threshold value and the usage amounts of the low density metallic ink S 1  and the high density metallic ink S 2  vary depending on the desired glossiness. However, the threshold value is not limited to the maximum gloss value B 1 max of the low density ink. That is, the threshold value may be properly set by taking the duty of the metallic ink and the graininess of the printed image into consideration. For example, when the graininess is not a serious problem in a range of a low duty, the threshold value may be set to be less than the maximum gloss value B 1 max of the low density ink. 
         [0059]    In another embodiment, the printer  200  can store the two kinds of the metallic inks including the metal pigment with densities different from each other, and the computer  100  uses one or a combination of the two kinds of the metallic inks in response to the special glossy effect required for the printed product, so that the fine granularity of the printed image can be compatible with the special glossy effect. However, metallic ink to be used is not limited to the two kinds of the metallic inks. For example, the printer  200  may store three kinds or more of metallic inks. In such a case, the computer  100  may use one or M combinations (M denotes an integer of 2 or more) of N kinds of the metallic inks (N denotes an integer of 3 or more) in response to the special glossy effect required for the printed product. Thus, the special glossy effect and the fine granularity can be controlled in a wider range, so that printing can be performed to obtain desired special glossy effect while properly ensuring the fine granularity. 
         [0060]    In another embodiment, the computer  100  prints the metallic region by varying the amount of the low density metallic ink S 1  used depending on the special glossy effect required for the printed product. However, a predetermined amount of the low density metallic ink S 1  may be used in a predetermined range (in  FIG. 7 , glossiness of B 3  to B 4 ) of the required special glossy effect. For example, as shown in  FIG. 7 , the low density metallic ink S 1  corresponding to a duty D 2  may be always used and the amount of the high density metallic ink S 2  used may be changed in a range of from zero to a duty D 3  according to the required special glossy effect. The predetermined range may be properly set. For example, the predetermined range may be set between the maximum gloss value B 1 max of the low density ink and the maximum gloss value B 2 max of the high density ink as shown in  FIG. 6 . Thus, the fine granularity can be ensured using the low density metallic ink S 1 , so that the fine granularity can be compatible with the special glossy effect. 
         [0061]    In another embodiment, the computer  100  uses one or a combination of the two kinds of the metallic inks in response to the special glossy effect required for the printed product, so that the fine granularity of the printed image can be compatible with the special glossy effect. However, only one of the two kinds or more of the metallic inks stored in the printer  200  may be always used. For example, as shown in  FIG. 8 , when the input glossiness is equal to or less than a threshold value B 5 , the metallic region may be printed only with the low density metallic ink S 1 . However, when the input glossiness is larger than the threshold value B 5 , the metallic region may be printed only with the high density metallic ink S 2 . In the case of using only the high density metallic ink S 2 , if the amount of the high density metallic ink S 2  used exceeds the amount corresponding to a duty D 5  smaller than the duty D 1 , the fine granularity can be compatible with the special glossy effect in a case in which the graininess of the printed image does not matter. 
         [0062]    In another embodiment, the glossiness is used as the index regarding the special glossy effect. However, the index regarding the special glossy effect is not limited thereto. That is, various indexes can be used. For example, an index value In 1  regarding the special glossy effect, which is expressed by Equation 1 below, may be used. Further, an index value In 2  regarding the special glossy effect, which is expressed by Equation 2 below, may be used. 
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         L* 2 : lightness when a light receiving angle is 0° (irradiation angle is −45°) 
         L* 3 : lightness when a light receiving angle is −65° (irradiation angle is −45°) 
       
     
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                    
                   2 
                 
               
             
           
         
       
     
         [0066]      FIG. 9A  is a graph showing the relationship between the density of metal pigment and the index value In 2  regarding the special glossy effect. As shown in  FIG. 9A , in the case of using the low density metallic ink S 1 , as the duty is increased, the index value In 2  regarding the special glossy effect is also increased. However, the slope of the increase in the index value In 2  is gentle and the index value In 2  does not reach  2  even if the duty has a value of 50. Meanwhile, in the case of using the high density metallic ink S 2 , as the duty is increased, the index value In 2  regarding the special glossy effect is also increased. However, the slope of increase in the index value In 2  is steep as compared with the case of using the low density metallic ink S 1 . Further, when the duty has a value of 50, the index value In 2  reaches about 6. Meanwhile, referring to  FIG. 4  showing the relationship between the index value (glossiness) and the duty, the peak of the index value (glossiness) is indicated by the duty D 1 , and the index value (glossiness) is reduced if the duty exceeds the peak. However, the peak of the index value In 2  regarding the special glossy effect does not occur in the duty range of 5 to 50 shown in  FIG. 9A . 
         [0067]    When the index value In 2  regarding the special glossy effect is received in Step S 100 , the computer  100  may determine the usage amounts of the low density metallic ink S 1  and the high density metallic ink S 2  based on  FIG. 9B  (Step S 106 ). That is, when the index value In 2  regarding the special glossy effect is equal to or less than a value I 1  (which corresponds to a duty D 6  of the low density metallic ink S 1 ), only the low density metallic ink S 1  is used. Further, when the index value In 2  regarding the special glossy effect is positioned between the value I 1  and a value I 2  (which corresponds to a duty D 6  of the high density metallic ink S 2 ), the amount of the low density metallic ink S 1  used may be gradually reduced and the amount of the high density metallic ink S 2  used may be increased. Determination of the usage amounts of the low density metallic ink S 1  and the high density metallic ink S 2  are not limited to the example of  FIG. 9B . That is, the determination of the usage amounts of the inks S 1  and S 2  may be performed in various ways, similarly to the embodiment in which the glossiness is employed as the index value. 
         [0068]    For example, an index value In 3  regarding the special glossy effect, which is expressed by Equation 3 below, may be used as an index value regarding the special glossy effect.  FIG. 10  is a graph showing the relationship between the density of metal pigment and the index value In 3  regarding the special glossy effect. The relation shown in  FIG. 10  is similar to the relation shown in  FIG. 9A , so the usage amounts of the low density metallic ink S 1  and the high density metallic ink S 2  may be determined similarly to the case of using the index value In 2  regarding the special glossy effect. 
         [0000]        In 3= L*   1   −L*   3    Equation 3 
         [0069]    In another embodiment, the printing system  10  (printing apparatus in a broad sense) including the computer  100  and the printer  200  performs the printing process as shown in  FIG. 5 . However, the CPU of the control circuit  260  of the printer  200  may perform printing process equal to the printing process. Thus, image data received from a digital camera and various memory cards and the like can be properly printed through the printer  200 , without using the computer  100 . 
         [0070]    In another embodiment, the printer  200  is a serial ink jet printer that forms ink dots by ejecting ink droplets on the print medium P while moving the ink ejection heads  244  to  249 . However, the printing scheme is not limited thereto. For example, the invention can be applied to a printer, in which ink ejection heads are arranged over a width of the print medium P, and a laser printer that forms dots by attaching toner powder of each color on the print medium using static electricity, instead of ejecting ink droplets. Further, when the invention can be applied to the laser printer, toner powder including metal pigment and the like is used instead of metallic ink. In addition, the invention can be properly applied to a press using a plate. 
         [0071]    The application program or functions described in this application may be implemented as software code to be executed by one or more processors using any suitable computer language such as, for example, Java, C++ or assembly using, for example, conventional or object-oriented techniques. The software code may be stored as a series of instructions, or commands on a computer-readable medium, such as a random access memory (RAM), a read-only memory (ROM), a magnetic medium such as a hard-drive or a floppy disk, or an optical medium such as a CD-ROM. Any such computer-readable medium may also reside on or within a single computational apparatus, and may be present on or within different computational apparatuses within a system or network. 
         [0072]    The present invention can be implemented in the form of control logic in software or hardware or a combination of both. The control logic may be stored in an information storage medium as a plurality of instructions adapted to direct an information processing device to perform a set of functions disclosed in embodiments of the present invention. Based on the disclosure and teachings provided herein, a person of ordinary skill in the art will appreciate other ways and/or methods to implement the present invention. 
         [0073]    The above description is illustrative and is not restrictive. Many variations of the invention will become apparent to those skilled in the art upon review of the disclosure. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the pending claims along with their full scope or equivalents. 
         [0074]    The embodiment of the invention has been described. However, the embodiment of the invention is not limited thereto. That is, various modifications can be made within the scope of the invention. For example, the invention can be realized in the form of a printing method, a program, a storage medium, a printed product and the like, as well as the printing apparatus.