JP5668964B2 - Method for outputting a color image to a recording medium - Google Patents

Description

  The present invention relates to a method for outputting a color image to a recording medium.

  2. Related Art Inkjet recording apparatuses that use resin-based or reactive ink such as photo-curing type or thermosetting type are known. In the case of using a photocurable ink, there is a merit that the formed image is excellent in weather resistance, but the surface of the recording medium is uneven because it is difficult to be absorbed by the recording medium.

  Japanese Patent Application Laid-Open No. 2004-228688 realizes a finish similar to that obtained by laminating an image surface without performing a lamination process, and adjusts the glossiness of the image according to the purpose of use of the image or the user's preference. It is described to provide an ink jet recording apparatus that can be used. The ink jet recording apparatus described in the cited document 1 is ejected from a color ink head that ejects color ink to a recording medium, a transparent ink head that ejects transparent ink, a color ink head, and a transparent ink head. ROM that stores a plurality of ejection total droplet number patterns that define the total number of droplets for each dot of ink to be used as a pattern, and the total number of ink droplets for each dot that are defined in the ejection total droplet number pattern And a control unit that controls the transparent ink head so that the number of droplets of the color ink discharged from the color ink head is subtracted from the transparent ink.

JP 2006-35688 A

  With the technique described in Patent Document 1, a finish similar to that obtained by laminating can be realized by adding a transparent ink, and irregularities due to the color ink on the surface of the recording medium are absorbed by the transparent ink. However, the unevenness of the color ink that forms each dot exists, and the unevenness of the color ink causes color mixing between adjacent dots, or the difference in the thickness of the laminate due to transparent ink is a cause of light reflection and refraction Therefore, there is a possibility that the intended color and appearance may not be obtained.

One embodiment of the present invention is a method for outputting a color image to a recording medium. This method includes the following steps.
-Adjusting the color of each dot of the color image by discharging at least one of a plurality of color inks onto the recording medium (color ink discharging step, color adjusting step).
-Before adjusting the above color (color adjusting step), discharging the base ink onto the recording medium so that the total number of droplets of ink forming each dot has a predetermined pattern (base) A step of discharging ink for use).

  In this method, the base ink is not particularly limited, but is preferably an ink that does not easily affect the color image to be formed, for example, a transparent ink, an achromatic ink such as white, or a light ink. When ink of primary color or a color close to the primary color is employed as the base ink, it is necessary to select the color ink for color adjustment in consideration of the color of the base ink in the color adjustment step.

  According to this method, a color image formed on the recording medium so as to have a desired pattern thickness can be obtained. A typical pattern is to make the total number of droplets constant, and form a recording medium in which a color image having a flat surface with no unevenness or suppressed unevenness is output (formed) on the surface ( Manufacturing, printing). The total number of droplets can be changed in accordance with the shape of the color image, or can be changed so as to have undulations, and a three-dimensional color image can be output.

  Furthermore, according to this method, the color ink for adjusting the color of the color image is present in parallel on the surface of the flat color image, for example. For this reason, it can suppress that the unevenness | corrugation of color ink becomes a factor of the color mixture between the adjacent dots, or the difference in the thickness of the laminate by transparent ink causes the factor of unintended light reflection and refraction. Therefore, it is possible to output a higher quality color image to the recording medium.

  In the step of discharging the base ink, dots that do not require color adjustment included in the color image are formed by discharging the base ink onto the recording medium so that the total number of droplets has a predetermined pattern. It is desirable to include that. When forming a color image, it is possible to output to a recording medium a color image that is not coated with color ink and that has a flat surface or a desired thickness including unevenness of a portion (location) that does not require color adjustment. Further, the contour of the portion to which the color ink is applied is formed by the portion that does not require color adjustment formed by the base ink that is applied first. Therefore, the spread of the color ink can be suppressed, and a color image with a clearer contour can be output to the recording medium.

  In this method, the total number of droplets is equal to or greater than the maximum number of droplets required to adjust the color of each dot. Further, before the step of discharging the base ink, the total number of droplets and each dot It is desirable to have a difference from the actual number of droplets required to adjust the color as the number of inks for the underlying ink (step of determining the number of inks for the underlying ink).

  The total number of droplets may be the same as the maximum number of droplets required to adjust the color of each dot. The total number of droplets may be larger than the maximum number of droplets required to adjust the color of each dot, and in this case, each dot is formed by ejecting at least one drop of base ink. That is, the total number of droplets may be the number of droplets from which at least one droplet of base ink is ejected. By applying at least one layer of base ink (one drop), the influence of the surface of the recording medium on the color image can be suppressed. When the recording medium is a chromatic color, it is possible to suppress the surface color from affecting the color image by applying an achromatic background ink such as white. In addition, when the recording medium is transparent, the influence of the reflection of the transparent medium can be suppressed by applying an opaque or translucent base ink such as white.

  The base ink is preferably opaque (ink having a light shielding property). In a color image in which multiple colors are expressed by laminating colored transparent or translucent photo-curing ink, for example, resin or reactive color ink such as UV ink, the base ink is opaque. By doing so, color mixture (crosstalk) between adjacent dots (colors) can be suppressed.

The predetermined pattern of the total number of drops includes gradually increasing the total number of drops toward the color image at or around the edge of the color image. It is possible to suppress the occurrence of a significant step at or around the edge of the color image.

  Another aspect of the present invention is an apparatus that outputs a color image to a recording medium. This apparatus includes a first head unit that discharges a plurality of color inks onto a recording medium, and a base so that the total number of ink droplets forming each dot is a predetermined pattern prior to the first head. And a second head portion that ejects the ink for use. According to this apparatus, it is possible to output a color image having color ink on the surface and having no dot unit unevenness or suppressing dot unit unevenness to a recording medium.

  The number of base ink ejections may be determined on the host device side such as a personal computer. Further, the control unit of this apparatus may include a function for obtaining the difference between the total number of droplets and the actual number of droplets required for adjusting the color of each dot as the number of inks for foundation ink.

  Yet another embodiment of the present invention is an apparatus that outputs a color image to a recording medium. The apparatus includes a first head unit that ejects a plurality of color inks onto a recording medium, a second head unit that ejects base ink prior to the first head, and first and second heads. And a control unit for controlling the operation of the unit. The control unit has a function of adjusting the color of each dot of a color image by discharging at least one of a plurality of color inks onto a recording medium, and a total droplet of ink forming each dot before adjusting the color. And a function of ejecting the base ink onto the recording medium so that the number has a predetermined pattern.

Yet another embodiment of the present invention is a method for controlling an apparatus that outputs a color image to a recording medium. The output device includes a first head unit that ejects a plurality of color inks onto a recording medium, and a second head unit that ejects base ink prior to the first head unit. This control method includes the following steps.
The second head unit discharges the base ink onto the recording medium so that the total number of ink droplets forming each dot has a predetermined pattern.
The first head unit adjusts the color of each dot of the color image by discharging at least one of a plurality of color inks onto the recording medium.

  Before this control method and the step of discharging the base ink, the difference between the total number of droplets and the actual number of droplets required to adjust the color of each dot is used as the number of base ink discharges. It is desirable to have a step of obtaining and storing in the output buffer of the second head unit. The total number of droplets may be the number of droplets from which at least one droplet of base ink is ejected. Alternatively, the total number of droplets may be controlled to be constant.

1 is a diagram showing a schematic configuration of a system including a printer and a personal computer. 6 is a flowchart for explaining an example of a printer control method. The figure which shows typically each dot formed by the method of this embodiment 4A illustrates an example in which a color image is formed on a recording medium, and FIG. 4B illustrates an example in which the image is covered with a transparent ink. The figure which shows typically each dot formed by another method of this embodiment. FIG. 4 is a diagram illustrating a configuration of edges of a color image formed according to the present embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a system that outputs (forms) a color image to a recording medium. The system 1 includes a personal computer (hereinafter referred to as a PC) 20 serving as a host device, and a printer (device that outputs a color image) that outputs (prints) data supplied from the PC 20 to a recording medium (medium) 90. 10 and the like. The printer 10 is an ink jet printer, and includes a head unit 11 provided to reciprocate on a recording medium 90, and a drive mechanism (not shown) that supports the head unit 11 and reciprocates on the recording medium 90. ). The head unit 11 is not limited to a serial type that reciprocates, but may be a line type (line head).

  The printer 10 further includes a transport device (feeder) 12 for sending the recording medium 90 to the head unit 11, a control device (control unit) 13 for controlling these, and a memory 14. The transport device 12 includes a plurality of transport rollers 12a for transporting the recording medium 90 in a predetermined posture, for example, horizontally with respect to the head unit 11. The conveyance device 12 intermittently conveys the recording medium 90 while conveying and stopping the recording medium 90 in accordance with the operation of the head unit 11.

  The head unit 11 of the printer 10 ejects photocurable ink, for example, ultraviolet curable ink (UV ink) that is cured by irradiation with ultraviolet rays. For this reason, the printer 10 of this example further includes an ultraviolet irradiation device (UV irradiation device) 15 installed downstream of the head unit 11 in the conveyance direction of the recording medium 90.

  The ultraviolet curable ink includes a radical polymerization ink containing a radical polymerizable compound as a polymerizable compound, a cation polymerization ink containing a cation polymerizable compound, and a hybrid type in which a radical polymerization ink and a cation polymerization ink are combined. An ink etc. can be mentioned. A photocurable ink is a photoinitiator that initiates a polymerization reaction between a polymerizable compound that is polymerized and cured with light other than ultraviolet light, and a polymerizable compound with light other than ultraviolet light, such as electron beams, X-rays, and infrared light. May be included. Further, the ink is not limited to the photo-curing type ink, and may be a resinous or reactive ink such as a thermosetting type.

  The recording medium 90 for which a color image is to be output by the printer 10 of this example may be various papers such as plain paper, recycled paper, and glossy paper, and may be a sheet-like material other than paper such as various fabrics and various non-woven fabrics. It may be a member, and may be a sheet-like object made of a material such as resin, metal, glass, or any other shape. However, when an object having a shape other than a sheet is used as a recording medium, it is preferable to employ a mechanism in which the head unit 11 moves relative to the object. Since the printer 10 of this example uses resinous ink that is cured by light or the like, a color image can be suitably formed on a recording medium such as non-absorbing resin.

  The PC 20 that supplies data for forming a color image to the printer 10 includes hardware resources for realizing a general-purpose computer such as a processor, a memory, and an input / output device. An OS 21 and an application program 22 that runs on the OS 21 are installed in the PC 20 so that contents including documents and images can be viewed, created, and edited. The PC 20 further includes a printer driver 23 having a function of converting multi-value data such as characters and images included in the content into print data (for example, binary data) 29 when the content is printed by the printer 10. Is installed. In the PC 20, the printer driver 23 is provided as a program recorded on a recording medium such as a hard disk or a ROM (not shown). The function as the printer driver 23 is realized by a processor (not shown) executing the program.

  The head unit 11 of the printer 10 includes a first head portion (first head) 11 a that discharges a plurality of color inks onto a recording medium 90 and a second head portion (second head) that discharges base ink. Head) 11b. The first head portion 11a includes a plurality of inkjet-type nozzles that respectively discharge a plurality of color inks. A typical first head 11 a includes four types of nozzles that discharge UV color inks of yellow (Y), magenta (M), cyan (C), and black (K) to the recording medium 90. Note that the number and / or color of the plurality of color inks ejected in the first head portion 11a is not limited to these.

  The second head portion 11b includes an inkjet nozzle that discharges a single type of base ink. The second head portion 11b is disposed upstream of the first head portion 11a in the paper feeding direction (the conveyance direction of the recording medium 90), and the recording medium 90 is grounded before the first head portion 11a. The UV ink for use is discharged. An example of the base ink is an opaque (light-blocking) white UV ink or a transparent UV ink (UV resin). Examples of the UV curable white ink include UV white ink 4600 series manufactured by Markem.

  One function of the memory 14 of the printer 10 is to temporarily store data supplied from the PC 20. The memory 14 includes a pattern storage unit 30 that stores the total number of droplets TDN and / or a pattern (function) of ink forming each dot, and a first buffer that stores data for the first head unit 11a. (A buffer for output of the first head unit 11a) 31 and a second buffer (buffer for output of the second head unit 11b) 32 for accumulating data for the second head unit 11b. The first buffer 31 stores printing data 29 supplied from the printer driver 23. In the pattern storage unit 30, the total number of droplets TDN is set as a fixed value or a function. If the total number of droplets TDN is a fixed value (constant value), a color image having a constant thickness is formed on the recording medium 90.

  The control unit 13 of the printer 10 includes a CPU, and controls each device included in the printer 10 according to a processing program 19 stored in the memory 14. For example, the control unit 13 controls the driving of the head unit 11, the operation of the first head unit 11a and the second head unit 11b, the operation of the ultraviolet irradiation device 15, and the like. The control unit 13 may perform control to eject one drop of each color ink per dot, and realizes one drop volume by discharging a plurality of small ink drops. The color image may be recorded by a so-called multi-drop method.

  The control unit 13 includes a difference calculation function 41, a background ink discharge function 42, and a color adjustment function (color ink discharge function) 43. The difference calculation function 41 adjusts the total number of droplets TDN ejected to form each dot of the color image and the color of each dot before ejecting the base ink from the second head unit 11b. The difference from the actual droplet number CDN required for the above is obtained as the ink discharge number UDN for the base, and is stored in the second buffer 32. The difference calculation function 41 sets the ejection number UDN of the base ink to the total droplet number TDN for dots that do not require color adjustment, that is, dots that have a droplet number CDN of zero.

  The base ink ejection function 42 is based on the ejection number UDN stored in the second buffer 32 before the color adjustment is performed by ejecting the color ink by the first head unit 11a. The base ink is ejected onto the recording medium 90. Therefore, for the dots from which the color ink is ejected by the first head portion 11a by the base ink discharge function 42, the base ink is set so that the total number of droplets TDN including the number of color ink droplets CDN is reached. Is discharged onto the recording medium 90. In addition, for the dots for which the color ink is not ejected by the first head portion 11a by the foundation ink ejection function 42, the foundation ink is ejected onto the recording medium 90 so that the total number of droplets TDN is reached.

  The color adjustment function 43 is based on the printing data 29 stored in the first buffer 31, and a plurality of color inks such as yellow (Y), magenta (M), cyan (C) and the like are recorded on the recording medium 90. The color of each dot forming a color image is adjusted by ejecting at least one color ink of black (K).

  In an example in which a color image is formed by ejecting ink of each color one by one, black (K) is used in one color, so the maximum number of droplets MDN required to adjust the color of each dot is yellow (Y ), Magenta (M), and cyan (C), respectively, “3”. Accordingly, the total droplet number TDN is a numerical value of 3 or more or a function indicating 3 or more. In the multi-drop method, the maximum droplet number MDN and the total droplet number TDN can be defined similarly.

  For the purpose of forming a color image with a flat surface on the recording medium 90, the total droplet number TDN may be set to a constant value (fixed value). An example of the total droplet number TDN in that case is a value equal to the maximum droplet number MDN, which is “3” in this example. The difference between the fixed total number of droplets TDN and the actual number of droplets CDN required to adjust the color of each dot by the printing data 29 is obtained as the ink ejection number UDN for the base, and the printing data 29 is used. Before discharging the color ink, the second head portion 11 b discharges the base ink onto the recording medium 90. For example, if the number of droplets CDN for adjusting the color of a certain dot is “2”, “1” droplets of base ink are ejected in advance. If the number of droplets CDN for adjusting the color of a dot is “3”, the base ink is not ejected in advance. Further, for dots that are not color-adjusted, “3” drops of base ink are ejected in advance.

  In this way, the total number of droplets TDN is formed for all dots forming a color image by discharging the base ink onto the recording medium 90 so that the total number of droplets TDN of the ink forming each dot is constant. Can be set to “3”, and the surface of the entire color image can be flattened.

  Note that when the purpose is to form a smooth color image on the recording medium 90 even if the surface is not flat, the total number of droplets TDN is sufficiently longer than the dot unit and has a long period. It can be defined by a function (pattern) that changes. By changing the total number of droplets TDN, a color image with a smooth surface or a color image smoothly swelled in a shape reflecting a pattern or a picture, for example, a color image is obtained. Can be formed (output) on top.

  FIG. 2 is a flowchart illustrating an example of a control method of the printer 10 of the present example. In step 101, color image data is input from the PC 20. In step 102, the number of droplets CDN for each dot that outputs a color image is calculated based on the print data 29. In step 103, for each dot, the difference UDN between the preset total droplet number TDN and the actual droplet number CDN is calculated. This difference becomes the ejection number UDN of the base ink. For dots that are included in the color image and do not require color adjustment, the ejection number UDN of the base ink is set to the total droplet number TDN.

  In step 104, before discharging the color ink, the second head unit 11b discharges the base ink by the number of droplets of the difference (discharge number) UDN to form the base of each dot forming the color image. . In the portion where the color ink is not ejected, dots are formed with the base ink.

  Thereafter, in step 105, the first head unit 11a applies at least one (a maximum of three colors) of yellow (Y), magenta (M), cyan (C), and black (K) to a predetermined color. Eject in order and adjust the color of each dot in the color image. In step 106, ultraviolet rays (UV) are irradiated to cure the ink and fix each dot. The ultraviolet rays may be irradiated to fix the base ink separately from the color ink after discharging the base ink in step 104. Further, each time ink of each color is ejected, the ink may be fixed with ultraviolet rays.

  FIG. 3 schematically shows each dot of the color image 95 output (formed) on the recording medium 90 by the method of this example. FIG. 4A schematically shows each dot when a color image 99 is formed by ejecting only the color inks 81Y, 81M, 81C and 81K on the recording medium 90 using the printing data 29. FIG. FIG. 4B shows the state of each dot of the color image 98 whose surface is covered with a transparent resin 89.

  As shown in FIG. 4A, when the color image 99 is formed by ejecting only the color inks 81Y to 81K, the number of ejected inks varies depending on the color represented by the dots. For this reason, the heights of the dots 99d forming the color image 99 are different, and the surface of the color image 99 is uneven. For this reason, since the surface of the color image 99 is physically uneven, there is a possibility that the touch may be uncomfortable, the foreign matter may be caught on the uneven surface of the color image, the image quality may be deteriorated, and the durability of the color image may be impaired. There is. Further, the height of the dot 99d differs depending on the color, and the color inks 81Y to 81C stacked from the lower side to form the dot 99d may be seen from an oblique direction depending on the conditions, and the adjacent dot 99d. There is also a possibility of color mixing between.

  As shown in FIG. 4B, since the height of the dots 98d forming the color image 98 is made constant by overlapping the transparent resin (droplet) 89, the surface of the color image 98 becomes smooth. However, the color inks 81Y to 81C are still stacked from the lower side (recording medium side), and there is a possibility of color mixing between adjacent dots. Furthermore, since the thickness and shape of the transparent resin 89 vary, there is a possibility that the intended color and appearance may not always be obtained due to unintended reflection or refraction. In particular, the UV inks 81 </ b> Y to 81 </ b> C are typically colored and transparent, so even if they are covered with the transparent resin 89, crosstalk is likely to occur between adjacent dots.

  In contrast, in the color image 95 formed by the method according to the present invention shown in FIG. 3, before the color inks 81Y to 81K are ejected, the difference UDM between the total droplet number TDN and the actual droplet number CDN. Only the base ink 85 is ejected and stacked on the recording medium 90. Therefore, the height of all the dots 95d forming the color image 95 is constant, and the color image 95 having a smooth and flat surface can be formed on the recording medium 90. Further, the color inks 81Y to 81K are not stacked from the bottom, that is, from the recording medium 90 side, but are stacked from the top in the opposite direction, that is, from the surface 95s of the surface of the color image 95. For this reason, since the surface 95s of the color image 95 is formed of any one of the color inks 81Y to 81K, the portion of the color image 95 that requires color adjustment is mixed between adjacent dots, unintended reflection, There is little refraction.

  Further, since the color image 95 is raised beforehand by the base ink 85 and the color inks 81Y to 81K are arranged on the surface 95s of the color image 95, the base ink 85 may not be transparent and is opaque. Thus, the ink 85 having a light shielding property can be used. By using the opaque base ink 85, crosstalk can be further suppressed. Furthermore, dots that do not require color adjustment of the color image 95, typically dots at the edge of the color image 95, can be formed by stacking opaque, for example, white base ink 85. Therefore, it is easy to emphasize the edge of the color image 95, and a sharper color image 95 can be formed on the recording medium 90.

  As described above, in the apparatus 10 and the method of this example, even if an ink that easily forms irregularities on the surface of the recording medium 90 such as a curable type, a resin property, or a reactive property such as a UV ink is used, the coloring surface is formed by the base ink. Therefore, a flat color image with a more natural texture can be obtained.

  As described above, the total number of droplets TDN is equal to or greater than the maximum number of droplets MDN required to adjust the color of each dot. The total number of droplets TDN can be made larger than the maximum number of droplets MDN, and the entire background of the color image 95 can be formed with the base ink 85.

  That is, the influence of the surface of the recording medium 90 can be reset by placing one or more layers of the base ink 85, and a high-quality color image 95 can be formed on the various recording media 90. For example, the total number of droplets TDN is set to “4”, and at least one drop of base ink may be applied onto the recording medium 90 before applying the color ink onto the recording medium 90. In the case of the transparent recording medium 90, the reflection from the opposite side can be suppressed by using the opaque base ink 85. In the case of the recording medium 90 having a ground color, the influence of the ground color can be suppressed by using the base ink 85 that can cancel the ground color.

  FIG. 5 shows different examples of color images output (formed) on the recording medium 90 by the method of this example. The color image 96 shown in FIG. 5 is output with the total droplet number TDN of each dot set to “4”. For this reason, before the color inks 81 </ b> C to 81 </ b> K are applied to the recording medium 90 by the first head portion 11 a, at least one drop (one layer) 86 of base ink on the recording medium 90 by the second head portion 11 b. 85 is applied. Also in this color image 96, since the thickness of each dot 96d is constant, a color image 96 having a smooth surface can be output to the recording medium 90. Further, since the color inks 81C to 81K are stacked from the surface 96s side of the color image 96, a clear color image can be obtained in the same manner as the color image 95 described above. Furthermore, since the influence of the ground color of the recording medium 90 can be suppressed by the base ink 85, a clearer color image can be obtained.

  In the above description, an example in which the total number of droplets TDN is set constant has been described. However, as described above, the total number of droplets TDN may be changed in a long-term cycle (pattern). Even in that case, the color ink is laminated from the surface side of the color image, and the color ink (at least one of a plurality of color inks) exists on the surface of the color image. For this reason, crosstalk can be suppressed, and deterioration of the quality of a color image due to reflection or refraction can be suppressed.

  As shown in FIG. 6, it is also effective to change the total number of droplets TDN stepwise or smoothly at or around the edge 97e of the color image 97. In the edge (boundary) area of a color image or an area (printing area) for printing a color image, droplets having a total droplet number TDN are rapidly stacked on the surface of the recording medium 90. Therefore, a step with a large difference may occur at the edge or the periphery of the color image or print area. The total number of droplets TDN is controlled so as to gradually increase as the color image 97 is approached at or around the edge 97e of the color image 97 or the print area using a function or a look-up table (LUT). By controlling the total number of droplets TDN in such a manner, it is possible to form an inclined or fine step on the edge 97e or the periphery of the color image 97 or the print region using the base ink 85. For this reason, it is possible to prevent a significant step from occurring at the edge or the periphery of the color image or the print area. In places where the level difference is remarkable, the touch becomes abnormal, the color image is easily damaged, foreign matter is easily accumulated, and the edge level difference can be reduced or smoothed to prevent such problems.

  In the above example, the difference calculation function 41 for calculating the total droplet number TDN and the like is implemented in the control unit 13 of the printer 10, but this function may be provided in the printer driver 23 of the PC 20.

  Further, in this example, yellow (Y), magenta (M), cyan (C), and black (K) color inks are used as color inks, but the color of the ink used is limited to this. It is not something. For example, eight colors including light yellow (LY), light magenta (LM), light cyan (LC), and light black (LK) may be used as the color ink. In this example, an opaque (light-shielding) ink is used as the base ink, but the base ink is not limited to this. For example, a colorless and transparent ink may be used.

10 Printer (A device that outputs a color image to a recording medium)
11a 1st head part, 11b 2nd head part 13 Control unit, 41 Difference calculation function, 42 Underground ink discharge function 43 Color adjustment function, 90 Recording medium

Claims (11)

A method for outputting a color image to a recording medium,
Adjusting the color of each dot of the color image by discharging at least one of a plurality of color inks onto the recording medium;
Before adjusting the color, discharging the base ink onto the recording medium so that the total number of ink droplets forming each dot has a predetermined pattern;
The predetermined pattern of the total droplet number includes gradually increasing the total droplet number toward the color image at or around the edge of the color image.   2. The discharge of the base ink according to claim 1 is performed so that the dots included in the color image do not require color adjustment and the base ink has a predetermined number of droplets. Forming by discharging onto the recording medium. In Claim 1 or 2, the total number of droplets is equal to or greater than the maximum number of droplets required to adjust the color of each dot,
Before discharging the base ink, the difference between the total number of droplets and the actual number of droplets required to adjust the color of each dot is obtained as the number of discharges of the base ink. Further comprising a method.   4. The method according to claim 3, wherein the total number of droplets is the number of droplets from which at least one droplet of the base ink is ejected.   5. The method according to claim 1, wherein the base ink is opaque. An apparatus for outputting a color image to a recording medium,
A first head unit that ejects a plurality of color inks to the recording medium;
Prior to the first head, a second head unit that ejects the base ink so that the total number of ink droplets forming each dot has a predetermined pattern;
A memory storing a predetermined pattern of the total number of droplets,
The apparatus, wherein the predetermined pattern of total droplet number includes gradually increasing the total droplet number toward the color image at or around an edge of the color image. In Claim 6 , it further has a control unit,
The total number of droplets is greater than or equal to the maximum number of droplets required to adjust the color of each dot,
The control unit includes a function of obtaining a difference between the total number of droplets and an actual number of droplets required for adjusting the color of each dot as the number of inks for the underlying ink. 8. The apparatus according to claim 6 , wherein the base ink is opaque. An apparatus for outputting a color image to a recording medium,
A first head unit that ejects a plurality of color inks to the recording medium;
A second head part for discharging ink for base prior to the first head part;
A control unit for controlling the operation of the first and second head portions,
The control unit is
A function of adjusting the color of each dot of the color image by discharging at least one of a plurality of color inks onto the recording medium;
Before adjusting the color, including a function of discharging the base ink onto the recording medium so that the total number of ink droplets forming each dot has a predetermined pattern,
The apparatus, wherein the predetermined pattern of total droplet number includes gradually increasing the total droplet number toward the color image at or around an edge of the color image. A method for controlling an apparatus for outputting a color image to a recording medium,
The output device includes a first head unit that ejects a plurality of color inks to the recording medium, and a second head unit that ejects base ink prior to the first head unit,
The control method is
The second head unit ejects the base ink onto the recording medium such that the total number of ink droplets forming the dots has a predetermined pattern;
The first head section includes adjusting at least one of a plurality of color inks onto a recording medium to adjust the color of each dot of the color image;
The control method, wherein the predetermined pattern of the total droplet number includes gradually increasing the total droplet number toward the color image at or around an edge of the color image. In claim 10 , the total number of droplets is greater than or equal to the maximum number of droplets required to adjust the color of each dot,
Before discharging the ink for the background, the difference between the total number of droplets and the actual number of droplets required to adjust the color of each dot is obtained as the number of ink discharged for the background. The control method further includes storing in an output buffer of the second head unit.

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