JP5877054B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus having a two-color or three-color printing function that forms a plurality of images on a recording medium so as to overlap each other with a single color or two chromatic inks and an achromatic ink.

  Conventionally, as one of image forming apparatuses, an ink jet printing apparatus using a so-called single-pass method has been used. In such a single-pass printing apparatus, a line head having a length longer than the width of the printing range is used, and when the recording medium passes once under the line head, all print areas are formed and printed. . In this single-pass printing apparatus, since it is necessary to provide a large amount of ink jet heads, the manufacturing cost of the entire apparatus is high and expensive. On the other hand, as an inexpensive inkjet print, there is a two-color printing apparatus that records an image by ejecting two colors of chromatic ink and achromatic ink onto a recording medium. However, in such an ink jet printing apparatus having only two colors, the number of colors of the printed matter is limited, so that there is a problem that the expressive power of the image is lowered.

  Here, there is a technique for improving expressive power by using colored paper for a two-color ink jet printing apparatus, but if expensive colored paper is used for all printing paper, the printing cost becomes high. There is also.

  In order to solve such a problem, there is, for example, Patent Document 1. In the technique disclosed in Patent Document 1, for example, by specifying a page part including a photo such as a cover, colored paper is fed to the page part, and a white recording medium is used for the other part. Paper is fed. Thereby, colored paper can be used only for a specific page from the entire printed matter, and the printing cost can be reduced.

JP-A-9-188017

  However, the technique disclosed in Patent Document 1 has a problem that the operation is complicated because it is necessary for the user to specify a page number for inserting colored paper. In addition, since there are various types of images in printed materials, it is difficult for the user himself to determine which color recording medium is optimal for the image to be printed for each page. The operation of was also cumbersome.

  This type of situation is common to various image forming apparatuses such as an electrophotographic system and a stencil printing system as well as an ink jet printing apparatus.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can acquire a pseudo color image corresponding to a full color image with low cost, effort, and high expressive power.

In order to solve the above-described problem, an image forming apparatus according to the present invention described in claim 1 includes:
The input full-color image data is color-converted, and based on the color-converted full-color image data, one or two kinds of chromatic recording material (for example, chromatic ink) and an achromatic recording material (for example, An image forming apparatus (for example, a head unit 110 in FIG. 1) is used to form a pseudo color image including two-color printing on a recording medium (for example, printing paper) using an achromatic ink. For example, the inkjet printing apparatus 100) of FIG.
Paper feeding means for selectively supplying recording media of a plurality of colors to the image forming means (for example, the paper feeding trays 120, 130 (130a, 130b, 130c) in FIG. 1, the transport roller 183, the paper transport means 370 in FIG. 2) When,
Of the chromatic colors present in the full-color image data, a color that can reproduce an approximate color with the pseudo-color image and has an occupation area ratio with respect to the full-color image equal to or greater than a predetermined value (for example, 3 in FIG. 10). An image from which “red” on the page or a predetermined color (for example, “skin color” on page 3 in FIG. 10) is set as one or a plurality of representative colors, and color information including data on the representative colors is acquired. Color information acquisition means (for example, the input image information acquisition unit 332 in FIG. 2);
Based on the color information, as a recording medium to be used for forming the pseudo color image, a recording medium having a color corresponding to the acquired color information is selected and fed to the image forming unit. A paper feed control means for controlling the paper feed means (for example, a paper feed switching control unit 333a in FIG. 2)
It is characterized by providing.

  The image forming apparatus of the present invention described in claim 2 is the image forming apparatus of the present invention described in claim 1, wherein the color information includes attribute data of the full-color image, and the full-color image. As color conversion patterns (for example, color conversion patterns in FIGS. 3A to 3C) used for color conversion of image data, a plurality of colors having different chromatic color conversion ranges used for forming the pseudo color image are used. Of the conversion patterns, color conversion selection means (for example, the color conversion pattern switching unit 333b in FIG. 2) for selecting a color conversion pattern corresponding to the color information, and the selected full color using the selected color conversion pattern Color conversion means (for example, a color conversion circuit 337b in FIG. 2) for color-converting image data, and the image color information acquisition means includes attribute data of the full-color image. And acquires the color information.

  Furthermore, the image forming apparatus according to the third aspect of the present invention is the image forming apparatus according to the first or second aspect, wherein the information on the color of the recording medium that can be selected by the paper feeding unit is acquired. Paper color information acquisition means (for example, paper color information acquisition unit 334 in FIG. 2) is further provided, and the paper feed control means feeds the recording medium having a color different from the representative color to the image forming means. The sheet feeding means is controlled.

  The image forming apparatus of the present invention described in claim 4 is the image forming apparatus of the present invention described in claim 3, wherein the sheet feeding control means is configured such that the representative color is a chromatic color constituting the pseudo color image. A white recording medium is selected when the hue is the same as or opposite to the chromatic color, and a chromatic recording medium is selected when the representative color is the adjacent hue of the chromatic color constituting the pseudo color image.

  Further, in the image forming apparatus of the present invention described in claim 5, in the image forming apparatus of the present invention described in claim 3, the paper feed control unit selects a chromatic recording medium that approximates the representative color. It is characterized by doing.

Further, the image forming apparatus of the present invention as set forth in claim 6, the paper to get Te image forming apparatus odor of the present invention according to claim 2, the information relating to the color of selectable the recording medium in the sheet feeding means A color information acquisition unit, wherein the paper feed control unit controls the paper feed unit to feed a chromatic recording medium similar to the representative color, unlike the representative color, to the image forming unit; with, before Symbol color converting means, of the full-color image data input, the image portion having the color information that approximates the color information of the selected said recording medium is printed onto a colorless the amount of recording material as 0 Color conversion processing is performed so that

  Furthermore, an image forming apparatus of the present invention described in claim 7 is the image forming apparatus of the present invention described in claim 6, wherein an image portion having color information approximate to the color information of the selected recording medium is selected. Among them, a conversion target area including any one of a character edge, an image outline or a point is extracted, and the extracted conversion target area is replaced with a pixel of color information different from the color information of the selected recording medium. A replacement processing unit (for example, an edge extraction unit 382 and a synthesis processing unit 383 in FIG. 17) is further provided.

  According to the present invention, a pseudo color image corresponding to a full color image can be acquired with low cost, effort, and high expressive power.

  That is, according to the image forming apparatus of the present invention described in claim 1, in an image forming apparatus that prints a pseudo color image using two or three color recording materials including an achromatic recording material, One or a plurality of colors are used as representative colors, and color information including data of the representative colors (chromatic colors) is acquired. Then, the paper feeding unit selects a color recording medium corresponding to the acquired color information and feeds it to the image forming unit to form a pseudo color image. On the other hand, when inputting image data of a monochrome image, the image forming means forms a monochrome image on a white recording medium as usual. Here, the representative color of the full-color image can be, for example, a chromatic color having the largest count number by counting the number of pixels for each constituent color of the full-color image.

  For this reason, it is possible to selectively select a recording medium of a color suitable for improving the expressiveness of a page for forming a pseudo color image without requiring the user to specify the color of the full color image page or the paper to be used in advance. Can be used for In addition, since an inexpensive white paper is used for a monochrome image as usual, the cost of the entire printed matter can be reduced. As a result, a pseudo color image corresponding to a full color image can be acquired with low cost, effort, and high expressive power.

  According to the above invention, when generating a pseudo color image corresponding to a full color image, a color conversion pattern corresponding to a representative color or attribute of the full color image is used for color conversion of full color image data. Here, as the color conversion pattern, a color conversion pattern that always assigns the color of the chromatic recording material to the color portion of the full-color image, or the recording material of the chromatic color only in the warm color system portion such as magenta, red, yellow, etc. Includes patterns that assign colors in a limited way.

  Therefore, for example, in a full-color image including characters in which the character that the user wants to emphasize is a color character, the color conversion pattern that assigns the color of the chromatic recording material to all the color character portions is used for color conversion, and the pseudo-color image Characters that you want to emphasize can be highlighted with chromatic colors. For full-color images including photographs, skin color and red color are given priority on the pseudo-color image by using a color conversion pattern that assigns the color of the chromatic recording material only to warm colors such as magenta, red, and yellow for color conversion. Can be expressed appropriately. As a result, the printed matter intended by the user can be acquired by the pseudo color image.

  According to the image forming apparatus of the present invention described in claim 3, when the pseudo color image corresponding to the full color image is formed on the recording medium in the image forming apparatus of the present invention described in claim 1 or 2, the full color A recording medium having a color different from the representative color of the image is used. In this case, the constituent colors of the full-color image other than the representative color can be expressed by a color mixture of the color of the chromatic recording material used for printing and the color of the recording medium, or by the color of the recording medium.

  For example, if the representative color is blue and the recording medium includes light blue paper, the blue color of the image can be expressed with a small amount of recording material by selecting the light blue paper. Also, for example, when the representative color is red or skin color, and the recording medium includes a yellow sheet, by selecting the yellow sheet, the magenta recording material and the yellow recording medium can be selected. The expression power of red and skin color can be improved. As described above, according to the present invention, more colors can be reproduced at low cost by automatically selecting colored paper having a color different from the representative color of the full-color image.

  In the image forming apparatus according to the fourth aspect of the present invention, the same hue, opposite hue, and adjacent hue are hues defined by positions on the hue circle. The hue circle is a pie chart in which the entire hue is arranged in an annular shape, and there is also one that shows the hue as an angle. On this hue circle, complementary colors are provided at opposite positions. Therefore, the same hue means a hue belonging to the same angle in the hue ring, the opposite hue means a hue belonging to an angle inverted by 180 degrees in the hue ring, and the adjacent hue is a range of adjacent angles in the hue ring. Refers to hues belonging to.

  According to the image forming apparatus of the present invention described in claim 4, the image forming apparatus of the present invention described in claim 3 is used when forming a chromatic color constituting a pseudo color image, that is, a pseudo color image. If the color of the chromatic recording material and the representative color of the full-color image have the same hue, the image part of the pseudo color image corresponding to the image part of the representative color of the full-color image is the chromatic color of the same color. Expressed in ink. Therefore, the recording medium used for forming the pseudo color image can be a low-cost white paper instead of a colored paper.

  Also, if the color of the chromatic recording material used to form the pseudo color image is a color opposite to the representative color of the full color image, temporarily use colored paper in combination with the chromatic recording material. However, a color close to the representative color of a full-color image cannot be expressed. For this reason, the image part of the pseudo color image corresponding to the image part of the representative color of the full color image is printed using the achromatic recording material (black recording material). Therefore, the recording medium used for forming the pseudo color image can be a low-cost white paper instead of a colored paper.

  Furthermore, when the color of the chromatic recording material used when forming the pseudo color image is a color of a hue adjacent to the representative color of the full color image, recording using the color of the chromatic recording material and colored paper A color that approximates the representative color of a full-color image can be expressed by a color mixture with the chromatic color of the medium. Therefore, a color printed matter can be obtained without printing by an expensive full-color printing machine.

  According to the image forming apparatus of the present invention described in claim 5, in the image forming apparatus of the present invention described in claim 3, a recording medium having a color close to the representative color of the full-color image is used for printing the pseudo color image. Thus, the image portion of the pseudo color image corresponding to the image portion of the representative color of the full color image can be expressed by the color of the recording medium without using the recording material. Accordingly, it is possible to obtain a color printed matter at a low cost while suppressing the amount of recording material used.

  7. The image forming apparatus according to claim 6, wherein the color conversion processing with a pixel value of 0 is, for example, an ejection amount of a recording material ejected from an ink head in the case of an ink jet printing apparatus. In the case of a thermal transfer printing apparatus, the voltage amount applied to the heating element is 0.

According to the image forming apparatus of the present invention as set forth in claim 6, for the image portion having the color information that approximates the color information of the record medium, by zero pixel values, the image by the representative color of the full-color image The image portion of the pseudo color image corresponding to the portion can be expressed by the color of the recording medium itself without using the recording material. Accordingly, it is possible to obtain a color printed matter at a low cost while suppressing the amount of recording material used.

  According to the image forming apparatus of the present invention described in claim 7, in the image forming apparatus of the present invention described in claim 6, even when the color information of the recording medium is used for image expression, Of the image portion to be expressed by the color of the recording medium, the replacement target portion is replaced with a pixel having color information different from the color information of the selected recording medium. For this reason, for example, the edge of the character and the outline portion of the image are printed with a color different from the color of the recording medium. Therefore, the image data information can be expressed without loss.

1 is a conceptual diagram illustrating an overall configuration of a printing system including an inkjet printing apparatus according to a first embodiment of the present invention. It is a block diagram which shows the functional module which concerns on the color conversion process in the arithmetic processing part of FIG. (A)-(c) is explanatory drawing which shows the color conversion pattern switched by the color conversion pattern switching part of FIG. 2, (d) is explanatory drawing which shows the color conversion pattern which can be produced theoretically. It is explanatory drawing of the color profile memorize | stored in the profile memory | storage part of FIG. It is explanatory drawing of the color profile memorize | stored in the profile memory | storage part of FIG. It is explanatory drawing of the color profile memorize | stored in the profile memory | storage part of FIG. It is explanatory drawing of the color profile memorize | stored in the profile memory | storage part of FIG. It is a flowchart figure which shows the process which the arithmetic processing part of FIG. 2 performs. FIG. 9 is a flowchart showing the printing paper selection process in FIG. 8. FIG. 9 is an explanatory diagram illustrating a color change state of an image that is printed from image data input by the processing of FIG. 8. FIG. 9 is an explanatory diagram illustrating a color change state of an image that is printed from image data input by the processing of FIG. 8. It is a flowchart figure which shows the process which the arithmetic processing part of FIG. 2 performs. It is a flowchart figure which shows the printing paper selection process of FIG. It is explanatory drawing which shows the state of the color change of the image printed from the image data input by the process of FIG. It is a flowchart figure which shows the printing paper selection process of FIG. It is explanatory drawing which shows the state of the color change of the image printed from the image data input by the process of FIG. It is a block diagram which shows the functional module which concerns on the arithmetic processing part of the inkjet printing apparatus which concerns on 2nd Embodiment of this invention. (A) is explanatory drawing which shows the filter of the edge extraction process processed by the edge extraction part of FIG. 17, (b) is explanatory drawing which shows the state which has arrange | positioned the filter on image data. (A) And (b) is explanatory drawing of the color profile memorize | stored in the profile memory | storage part of FIG. It is a flowchart figure which shows the replacement process of FIG.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

[First embodiment]
(Overall configuration of printing system)
FIG. 1 is a conceptual diagram showing an overall configuration of a printing system including an inkjet printing apparatus according to a first embodiment of the present invention. In this embodiment, an ink jet printing apparatus (corresponding to the image forming apparatus in the claims, hereinafter abbreviated as “printing apparatus”) 100 ejects black and magenta inks in units of lines. A case where the ink jet printer is a single-pass ink-jet printer that performs printing in FIG. In this printing apparatus 100, when a print head (corresponding to a recording medium in claims) passes once under the line head using a line head having a length equal to or greater than the width of the print range, all print areas are printed. Form and print.

  In the present embodiment, the printing system includes a user terminal 200 and a printing apparatus 100. The user terminal 200 is an arithmetic processing unit equipped with a CPU, and can be realized by a general-purpose computer such as a personal computer or a dedicated device specialized in functions, such as a mobile computer, a PDA (Personal Digital Assistance), a mobile phone. It may be.

  In the present embodiment, as shown in FIG. 1, a printing apparatus 100 and a plurality of user terminals 200 are connected to the network 3. The network 3 is a wireless network such as a local network (LAN) or a wireless LAN (WLAN) based on 10BASE-T or 100BASE-TX using the communication protocol TCP / IP. This wireless network includes, for example, a simple network such as a peer-to-peer home network.

  As shown in FIG. 1, the printing apparatus 100 is an apparatus that forms images so as to overlap each other on a sheet surface conveyed on an annular conveyance path. The transport path is a paper feed system transport path FR that supplies paper, and the paper feed system transport path FR to the paper discharge path DR through the head unit 110 that is an image forming unit (corresponding to image forming means in claims). To the normal route CR, and a reverse route SR branched and connected to the normal route CR.

  As a paper feed mechanism (corresponding to the paper feed means in the claims) for supplying printing paper, a side paper feed tray 120 disposed outside the side of the housing and a plurality of paper feeds provided inside the housing The tray 130 (130a, 130b, 130c) is provided. The paper feed mechanism includes a transport roller group including a transport roller 183 for transporting the printing paper on the paper feed system transport path FR from the trays 120 and 130 to the image forming unit (head unit 110). It has been. Note that a sheet transport unit 370 (see FIG. 2), which will be described later, is configured by these sheet feeding mechanisms. Further, as a paper discharge mechanism for discharging the printed print paper, a transport roller group for transporting the print paper on the paper discharge path DR and a paper discharge port 140 are provided.

  In this embodiment, each of the trays 130a, 130b, and 130c of the paper feed tray 130 stores yellow and light blue print paper and white paper in one of the paper feed trays. Color printing paper is selectively supplied to the image forming unit.

  The printing paper fed from one of the paper feed trays 130 of the paper feeding mechanism is transported along a paper feeding system transport path FR in the housing by a driving mechanism such as a roller, and at the reference position of the leading portion of the printing paper. It is guided to a certain resist portion R. The printing paper is supplied to the registration rollers of the registration unit R by driving the rollers upstream of the registration rollers.

  On the other hand, a head unit 110 having a plurality of print heads is provided on the side of the registration portion R in the transport direction. The printing paper is conveyed at a speed determined by printing conditions by a conveying belt 160 provided on the opposite surface of the head unit 110. Then, an image is formed line by line with the ink ejected from each print head on the printing paper being conveyed.

  The printed printing paper is further conveyed on the normal route CR by a driving mechanism such as a roller. In the case of single-sided printing, in which printing is performed only on one side of the printing paper, the paper is directly discharged to the paper discharge port 140 through the paper discharge route DR, and is discharged as a tray for the paper discharge port 140. It is loaded on the table 150 with the printing surface facing down. The paper discharge table 150 has a tray shape protruding from the housing, and has a certain thickness. The paper discharge table 150 is inclined, and the printing paper discharged from the paper discharge port 140 is naturally arranged and overlapped by a wall formed at a position below the inclination.

  In addition, in the case of duplex printing in which printing is performed on both sides of the printing paper, the image on the back side of the document is printed on the printing paper in order to discharge the paper on the front side of the printing paper on which the image on the front side of the document is printed (face down). First, printing is performed on the back side of the document, and then an image on the front side of the document is printed on the front side of the printing paper. Accordingly, the printing paper is not guided to the paper discharge path DR when printing on the back surface is finished, but is further conveyed in the housing and sent to the reversing path SR. A switching mechanism 170 is provided at a branch point between the paper discharge path DR and the reversal path SR to switch the conveyance path of the printing paper. When the printing on the back surface is completed and the printing on the front surface is performed, the switching mechanism 170 is drawn into the reversing path SR.

  In the reversing path SR, the sheet is delivered from the normal path CR, and so-called switchback is performed in which the sheet is reversed by reciprocating the sheet. Then, it is returned to the normal route CR via the switching mechanism 172 by a driving mechanism such as a roller, is re-fed through the registration portion R, and printing on the front surface is performed by the same procedure as that on the back surface. After that, the printing paper on which images are formed on both sides is conveyed on the normal route CR, and is then sent out to the discharge route DR by the switching mechanism 170, and is guided to the paper discharge port 140 and discharged in a direction with the surface facing down. The paper is fed and stacked on a paper discharge tray 150 provided as a receiving tray for the paper discharge outlet 140.

  In the printing apparatus 100, the printing paper that has already been printed on one side during double-sided printing is also re-fed to the registration portion R, which is the reference position of the leading portion of the fed printing paper. For this reason, a junction point where the feeding path of the newly fed printing paper and the refeeding path where the backside printing paper is circulated and joined is formed immediately before the registration portion R. Is done. Then, the registration unit R sends out the paper on the downstream side of the merging point between the paper feed conveyance path FR and the normal path CR.

  The conveying belt 160 is wound around a driving roller 161 and a driven roller 162 disposed at the front end and the rear end of the surface facing the head unit 110 in the normal path CR. Rotate. In the head unit 110 serving as an image forming unit, black and magenta ink heads are arranged side by side along the belt movement direction of the transport belt 160. In the head unit 110, a two-color printed image is formed by overlapping a plurality of images with a single chromatic ink (here, magenta) and an achromatic ink.

  Further, as illustrated in FIG. 1, the printing apparatus 100 includes an arithmetic processing unit 330 that is an arithmetic module. The arithmetic processing unit 330 is configured by a processor such as a CPU or DSP (Digital Signal Processor), memory, hardware such as other electronic circuits, software such as a program having the function, or a combination thereof. The The arithmetic processing unit 330 virtually constructs various functional modules by appropriately reading and executing the program. Each constructed functional module performs processing related to image data, operation control of each unit, and various processing for user operations. In addition, an operation panel 340 is connected to the arithmetic processing unit 330, and an instruction and a setting operation by a user can be received through the operation panel 340.

  The printing apparatus 100 also has a function of printing job data received from the user terminal 200 through the network 3 in accordance with a print instruction based on a user operation. Specifically, the user terminal 200 connected to the printing apparatus 100 via the network 3 is provided with an application such as a printer driver. By executing this application, a print job is transmitted from the user terminal 200 to the printing apparatus 100 through a communication interface 360 such as a LAN. In the printing apparatus 100 that has received the print job, the arithmetic processing unit 330 executes print processing based on the print data and the execution command in the print job.

(Functions related to color conversion processing)
The color conversion processing function in the present embodiment is realized by controlling the operation of the head unit 110 and each driving unit by the arithmetic processing unit 330 provided in the printing apparatus 100. FIG. 2 is a block diagram illustrating functional modules related to color conversion processing in the arithmetic processing unit 330. The “module” used in the description refers to a functional unit that is configured by hardware such as an apparatus or a device, software having the function, or a combination thereof, and achieves a predetermined operation. .

  As shown in FIG. 2, the arithmetic processing unit 330 mainly includes a job data receiving unit 331, an image processing unit 337, an input image information acquisition unit 332 (corresponding to image color information acquisition means in claims), color conversion, A control unit 333, a paper color information acquisition unit 334 (corresponding to a paper color information acquisition unit in claims), a paper information storage unit 335, and a profile storage unit 336 are provided.

  The job data receiving unit 331 is a communication interface that receives job data that is a series of print processing units. The job data receiving unit 331 is also a module that transfers data included in the received job data to the input image information acquisition unit 332 and the color conversion circuit 337 b in the image processing unit 337. Note that the communication here includes, for example, a short-range communication such as an infrared communication as well as a LAN such as an intranet (in-house network) or a home network based on 10BASE-T or 100BASE-TX. Here, in addition to the print image data defined in RGB, the job data includes resolution, the number of printed sheets, a paper size, a paper type, and a print mode as additional information.

  The input image information acquisition unit 332 is a module that analyzes image data on each printing paper surface. Specifically, the input image information acquisition unit 332 analyzes image data included in the job data received by the job data reception unit 331 and acquires color information of the input image related to image formation in the image processing unit 337. . Specifically, information indicating whether the image data input for each page is a color image or a monochrome image, and if the input image is a color image, further, among the colors constituting the color image Data (chromatic color data) indicating a typical chromatic color (single color) is acquired as color information of the input image.

  As a method for determining whether each page of the image data is a color image, it is determined whether each pixel is a color pixel, and when there are a predetermined number or more of color pixels, A method of determining that the page is a color image is used. Further, as a method for acquiring chromatic color data, for example, the number of pixels in a color image having the same color data for each of several candidate chromatic colors is counted, and the chromatic color (representative) Color) is used as chromatic color data for each page. This method is a method for determining chromatic color data when a color having an occupation area ratio with respect to a color image is a predetermined value or more and a color that can reproduce an approximate color by a pseudo color image to be described later is used as a representative color. one of.

  Note that the method of acquiring chromatic color data that is a representative color of a color image is not limited to this, and various methods may be used. For example, when there are two or more colors with a high count number and there is no difference between the count numbers, the candidate color (corresponding to the designated color in the claims) of red and skin color or a hue close thereto is used as the chromatic color data. Also good. This is to improve the expressive power of a person with the highest priority for an image including a photograph of a person or the like. In addition, the criteria for determining the color information of the input image by the input image information acquisition unit 332 may be changeable by the user. For example, through the operation panel 340, the user can change and specify the determination criterion parameters and the like.

  The input image information acquisition unit 332 also has a function of analyzing image data and determining an attribute for each page of the document. Here, the attribute to be determined is a character document, a graphic document, a photo document, or the like, and is generated as attribute information. The color information and attribute information of these input images are transmitted to the color conversion control unit 333.

  The paper color information acquisition unit 334 is a module that acquires paper type data. The paper type data can be acquired based on the paper settings received from the operation panel 340 and the communication interface 360. In addition, information regarding each color of a plurality of types of paper that can be selected by the paper feed mechanism detected by the paper detection mechanism 350 can be acquired as paper type data. The information on the color of the paper includes whether it is white or the hue of the colored paper, and the paper type such as plain paper or inkjet paper. This information may be acquired from a printer driver performed by the user or a paper setting in the operation panel 340. Alternatively, the color of the paper fed by the paper feed mechanism may be detected and acquired. For detecting the paper color, a sensor that irradiates the paper with spot light and determines the color by analyzing the color components of the reflected light can be used. The acquired data is input to the paper information storage unit 335.

  Note that the printer driver is an application or middleware executed by each client PC on the network when the printing apparatus 100 is used like a network printer, for example. The printer driver can transmit print data and an execution command to the printing apparatus 100 through a communication interface such as a LAN. The paper detection mechanism 350 is a mechanism that detects the size, paper color information, and the like of the printing paper that is to be printed in the image forming unit (head unit 110).

  The paper information storage unit 335 stores in which paper feed tray 130 (130a to 130c) what color printing paper is stacked, and when performing image printing, the paper conversion storage unit 333 stores these pieces of information. To send to. The paper information storage unit 335 stores information relating to the paper color transmitted from the paper color information acquisition unit 334 and information about the paper feed tray 130 in association with each other.

  The color conversion control unit 333 is a module that selects printing papers with different colors or switches color conversion patterns according to color information of the input image. The color conversion control unit 333 receives corresponding data from the profile storage unit 336 according to the printing process. Read and process. The color conversion control unit 333 includes a paper feed switching control unit 333a (corresponding to a paper feed control unit in claims) and a color conversion pattern switching unit 333b (corresponding to a color conversion selection unit in claims). Yes.

  The color conversion pattern switching unit 333b is a module that switches color conversion patterns in accordance with color information and attribute information of an input image. In this embodiment, a plurality of color conversion patterns are accumulated in the profile storage unit 336, and when color information of an input image is input, a predetermined color conversion pattern is selected.

  This color conversion pattern defines which color is printed with chromatic ink and which color is printed with achromatic ink when two colors of input full color image data are printed. In this embodiment, as shown in FIGS. 3A to 3D, a plurality of color conversion patterns are used. Note that the color conversion pattern shown in FIG. 3 is a polygon that is divided into six equal colors that match the hue circle. The hue circle is a pie chart in which the entire hue is arranged in an annular shape, and there is also one that shows the hue as an angle. On this hue circle, complementary colors are provided at opposite positions. Further, in FIGS. 3A to 3D, areas to which achromatic ink, that is, K (black) ink is allocated are indicated by hatching. Similarly, an area to which chromatic ink (M (magenta), C (cyan), or Y (yellow) ink) is assigned is indicated by dot hatching.

  As shown in FIG. 3A, the chromatic / achromatic conversion pattern is set to print with chromatic ink (magenta) for all of the warm RYM color and the cold CGB color. In conventional two-color printing, this chromatic / achromatic conversion pattern is exclusively used. In two-color printing using a chromatic / achromatic color conversion pattern, it is possible to reproduce color characters and color graphics with high expressiveness, rather than performing monochromatic printing while using inexpensive white on paper.

  Also, as shown in FIG. 3B, the red pseudo color conversion pattern converts Y (yellow) to M (magenta) to magenta with the R (red) color as the center, and other C ( The cyan, G (green), and B (blue) colors are set to be converted to achromatic colors. This red pseudo color conversion pattern can be combined with paper of an appropriate color to reproduce an input image including a photograph with high expressiveness. For example, by combining white paper and M (magenta) ink, magenta flowers and costumes can be expressed with good reproducibility at low paper cost. In addition, by combining yellow paper and M (magenta) ink, a person (skin color) close to the hue of R (red), red food (cow, fish, etc.), etc. can be reproduced with high expressiveness. .

  Further, as shown in FIG. 3C, the blue pseudo color conversion pattern converts B (blue) to C (cyan) to M (magenta) to magenta, and other G (green). , Y (yellow), and R (red) are converted to achromatic colors. In the blue pseudo color conversion pattern, purple can be expressed by combining light blue paper and magenta. Further, when using light blue paper, the same light blue sea or sky as the paper color can be expressed by paper color by processing as a colorless image not printed using M (magenta) ink. .

  Note that in all color conversion patterns, saturation is also taken into consideration, and as shown in FIGS. 3A to 3C, a color below a certain saturation (the central portion in the figure) is an achromatic color. Is converted to black.

  Incidentally, a magenta pseudo color conversion pattern for converting magenta of an input image into magenta can also be actually created. As shown in FIG. 3D, in the magenta pseudo color conversion pattern, M (magenta) is converted to magenta from R (red) to B (blue), and the other Y (yellow), G (green) and C (cyan) colors are converted to achromatic colors.

  However, in the printing apparatus 100 of the present embodiment, the magenta color pseudo color conversion shown in FIG. 3D is not used, and the red color pseudo color conversion shown in FIG. The reason is that skin colors often exist in natural images, and as described above, red pseudo color conversion is superior to magenta pseudo color conversion in skin color reproducibility. Further, even if the red pseudo color conversion is used, the magenta color in the input image can be expressed in the magenta color on the print image by the combination of the blank paper and the M (magenta) ink.

  The color conversion pattern switching unit 333b also has a function of adjusting the color information of the image data based on the selected color conversion pattern and the selected printing paper. This function performs color conversion of a specific color portion in the color conversion pattern. Specifically, among the input full-color image data, for the image portion having color information approximate to the color information of the selected printing paper, the color conversion is performed so that the amount of recording material is 0 and the printing is colorless. To process. Further, for example, when a blue pseudo color is selected as the color conversion pattern and a light blue printing paper is selected as the printing paper, the light blue portion of the image data is regarded as colorless in the printing process with the amount of recording material set to 0. Make fine adjustments such as copying. This is to prevent unnecessary image formation with ink when an image can be expressed in hue with the paper color of the printing paper.

  The paper feed switching control unit 333a is a module that controls the selection of print paper in the paper feed mechanism according to the color information of the input image. Specifically, the paper feed switching control unit 333a stores the profile based on information on whether it is a monochrome image or a color image, color information such as chromatic color data that is a representative color for the color image, and information on the color of the printing paper. The printing paper of the color to be used is selected with reference to the color conversion profile stored in the part 336. Then, the paper feed switching control unit 333a drives and controls the paper transport unit 370 based on the information of the paper feed tray 130 on which the selected print paper is stacked, and images the target print paper from the paper feed tray 130. Transport to forming part.

  The profile storage unit 336 stores printing paper and color conversion pattern selection conditions when performing two-color printing, and transmits selection conditions corresponding to input image data to the color conversion control unit 333.

  Specifically, as shown in the explanatory diagrams of FIGS. 4 to 7, the profile includes color information of image data (including color or monochrome information and chromatic color data as a representative color), attribute information of image data, The printing paper and the color conversion pattern are selected according to the respective conditions such as the color information of the printing paper loaded on the printing apparatus and the color information of the ink used. Therefore, the color conversion control unit 333 refers to the corresponding profile based on the information on the ink and printing paper used at the time of printing. For this profile, the user may select a profile or change the definition of this profile.

  In the present embodiment, in this profile, if the printing paper includes chromatic printing paper that approximates the chromatic color data of the input image calculated from the color information of the input image, the approximate chromatic color is included. Defined to select printing paper. Further, in this profile, when the color information of the image formed by the image forming unit (head unit 110) and the chromatic color data of the image data have the same hue or opposite hue, an achromatic printing paper is selected. Is defined as On the other hand, when the color information of the image formed by the image forming unit and the chromatic color data of the image data are adjacent hues, the chromatic color printing paper is selected.

  Here, the same hue, opposite hue, and adjacent hue are hues defined by positions on the hue circle. The hue circle is a pie chart in which the entire hue is arranged in an annular shape, and there is also a graph showing the hue as an angle. On this hue circle, complementary colors are provided at opposite positions. Therefore, the same hue means a hue belonging to the same angle in the hue ring, the opposite hue means a hue belonging to an angle inverted by 180 degrees in the hue ring, and the adjacent hue is a range of adjacent angles in the hue ring. Refers to hues belonging to.

  Hereinafter, each profile will be described with reference to the explanatory diagrams of FIGS. First, FIG. 4 shows printing paper colors and color conversion pattern selection conditions when white paper and yellow printing paper are stacked on the paper feed tray 130 and two-color printing is performed with black and magenta inks. Yes. Specifically, as shown in FIG. 4, it is determined whether the image data is a monochrome image or a color image. When the image data is a monochrome image, a gray scale is selected as the color conversion pattern, and printing paper is used. A blank sheet is selected.

  On the other hand, when the input image data is a color image, a red pseudo color as shown in FIG. 3B is selected for the color conversion pattern. The printing paper is selected based on the above definition by comparing the chromatic color data in the image data with the color (magenta) of the ink used for printing.

  For example, when the chromatic color data of the input image is a magenta color that has the same hue as the ink color (magenta) used to print the input image, a blank sheet is selected and green that is the hue located in the opposite direction In this case, blank paper is selected.

  On the other hand, if the chromatic color data of the input image is a hue color adjacent to the ink color (magenta), it is determined whether a chromatic color printing paper approximate to the chromatic color data is included. Then, when there is an approximate chromatic color print paper, the print paper of that color is selected, and when there is no approximate chromatic color print paper, a blank paper is selected.

  Specifically, when the chromatic color data of the input image is a color of a hue adjacent to the ink color (magenta), and is red or flesh color located counterclockwise on the hue ring with respect to the ink color In this case, a yellow paper that is a chromatic color printing paper that approximates the chromatic color data is selected. Further, for a blue color that is adjacent to the ink color (magenta) in which the single chromatic color data is used and is positioned in the clockwise direction on the hue ring with respect to the ink color, it approximates the chromatic color data. Since there is no chromatic color printing paper, blank paper is selected.

  In the present embodiment, the color of the printing paper and the color conversion pattern are also selected when two-color printing is performed with black and magenta inks loaded with white paper and light blue printing paper. The selection conditions are as shown in the explanatory diagram of FIG.

  Specifically, as shown in FIG. 5, first, it is determined whether the image data is a monochrome image or a color image. If the image data is a monochrome image, a gray scale is selected for the color conversion pattern, and Blank paper is selected as the printing paper.

  On the other hand, when the input image data is a color image, a blue pseudo color as shown in FIG. 3C is selected for the color conversion pattern. Further, the chromatic color data of the image data is compared with the color (magenta) of the ink used for printing, and the printing paper is selected from the comparison result.

  For example, when the chromatic color data of the input image is a magenta color that has the same hue as the ink color (magenta) used to print the input image, a blank sheet is selected and green that is the hue located in the opposite direction In this case, blank paper is selected.

  On the other hand, when the chromatic color data of the input image is a hue color adjacent to the ink color (magenta) and is a red or flesh color located counterclockwise on the hue ring with respect to the ink color, Since there is no chromatic color printing paper that approximates the chromatic color data, blank paper is selected. Further, the chromatic color data of the input image is a color of a hue adjacent to the ink color (magenta) used for printing the input image, and the blue color is positioned in the clockwise direction on the hue ring with respect to the ink color. The light blue printing paper that is the chromatic printing paper that approximates the chromatic color data is selected.

  In the present embodiment, when two-color printing is performed with black and magenta ink on which white paper and yellow printing paper are stacked, color image attribute information, that is, printing is text or graphics, or The color of the printing paper and the color conversion pattern are selected depending on whether it is a photograph. The selection conditions are as shown in the explanatory diagram of FIG.

  Specifically, as shown in FIG. 6, first, it is determined whether the image data is a monochrome image or a color image. If the image data is a monochrome image, a gray scale is selected for the color conversion pattern, and Blank paper is selected as the printing paper.

  On the other hand, when the input image data is a color image, the attribute of the image data is determined. When the attribute of the image data is a character or a graphic, a chromatic / achromatic color pattern as shown in FIG. 3A is selected giving priority to the reproducibility of the color character or the color graphic. On the other hand, when the attribute of the image data is a photograph, a red pseudo color as shown in FIG. 3B is selected giving priority to the skin color and red reproducibility that are often present in natural images. As for the selection of the printing paper, the chromatic color data of the input image is compared with the ink color (magenta) used for printing the input image, and the printing paper is selected from the comparison result.

  Here, when the chromatic color data of the image data is a hue color adjacent to the ink color (magenta) and is a red or flesh color located counterclockwise on the hue ring with respect to the ink color, Regardless of whether the attribute of the image data is a character or a graphic or a photograph, a yellow paper that is a chromatic color printing paper that approximates the chromatic color data is selected.

  In addition, when the chromatic color data of the input image is a magenta color having the same hue as the ink color (magenta), blank paper is selected. Further, in the case where the chromatic color data of the input image is a hue color adjacent to the ink color (magenta) and is located in the clockwise direction on the hue ring with respect to the ink color, the chromatic color data approximates the chromatic color data. Since there is no chromatic printing paper, blank paper is selected. Also, blank paper is selected in the case of green, which is a hue located in the opposite direction of the ink (magenta) used for printing the input image.

  Further, in the present embodiment, even when white paper and blue and yellow printing paper are stacked and two-color printing is performed with black and magenta ink, and the attribute information of the color image is included, the printing paper is also used. The color and the color conversion pattern are selected, and the selection conditions are as shown in the explanatory diagram of FIG.

  Specifically, as shown in FIG. 7, first, it is determined whether the image data is a monochrome image or a color image. If the image data is a monochrome image, a gray scale is selected for the color conversion pattern, and Blank paper is selected as the printing paper.

  On the other hand, when the input image data is a color image, the attribute of the image data is determined. When the attribute of the image data is a character or a graphic, a chromatic / achromatic color pattern as shown in FIG. 3A is selected.

  On the other hand, if the attribute of the image data is a photograph, the area and density of the R (red) and B (blue) pixels in the image data are calculated, and color conversion is performed based on the pixels with high numerical values. Set the pattern.

  Specifically, when the chromatic color data of the input image is red or skin color, the red pseudo color is selected because there are many R (red) pixels. On the other hand, when the chromatic color data of the input image is blue, since there are many B (blue) pixels, the blue pseudo color is selected. In the present embodiment, as shown in FIG. 7, when the chromatic color data of the input image is magenta or green, the red pseudo color is selected assuming that there are many R (red) pixels.

  The selection conditions for the printing paper are the same regardless of whether the attribute of the image is a character, a graphic, or a photograph. The printing paper in this case is selected by comparing the chromatic color data of the input image with the ink color (magenta) used for printing the input image.

  Specifically, when the chromatic color data of the image data is a hue color adjacent to the ink color (magenta), and the red or flesh color is positioned counterclockwise on the hue ring with respect to the ink color, A yellow paper that is a chromatic color printing paper approximate to the chromatic color data is selected. In addition, when the chromatic color data of the input image is a magenta color having the same hue as the ink color (magenta), blank paper is selected. In addition, the chromatic color data of the input image is a hue color adjacent to the ink color (magenta), and in the blue color positioned in the clockwise direction on the hue ring, the chromatic color printing paper that approximates the chromatic color data is used. A light blue printing paper is selected. Also, blank paper is selected in the case of green, which is a hue located in the opposite direction of the ink (magenta) used for printing the input image.

  The image processing unit 337 is an arithmetic processing device that performs digital signal processing specialized for image processing, and is a module that performs image data conversion necessary for printing and executes printing. The image processing unit 337 includes an image formation control unit 337a and a color conversion circuit 337b (corresponding to color conversion means in claims). The color conversion circuit 337b is a circuit that performs color conversion of an input image in accordance with the control of the color conversion control unit 333. Specifically, the RGB conversion image is converted into an MK two-color print image, and the print image for each color is displayed. Based on the above, the image formation control unit 337a executes printing. In particular, in the present embodiment, the color conversion circuit 337b refers to the color conversion pattern switched by the color conversion pattern switching unit 333b and expresses each color of RGB with M (magenta) and K (black) inks. Perform color conversion.

  The image formation control unit 337a is a module that controls the driving of the ink heads of the respective colors and controls the entire image formation processing, and performs image formation at a timing and a printing speed according to a schedule.

(Color conversion control operation)
Next, a color conversion operation in the printing apparatus having the above configuration will be described. Note that job data used for the color conversion operation described below is image data for five pages read from a document as shown in FIG. The first page of the document is a printed material in which black characters are printed on a white paper, and the second page is a printed material in which red, magenta, blue, and green characters are printed on a white paper. The third page of the manuscript is a printed matter in which a face photograph having a flesh color or a photograph having a red color is printed on a white paper, and the fourth page is a printed matter in which a photograph of a flower having a magenta color is printed on a white paper. . Finally, the fifth page of the manuscript is a printed matter on which a photograph in which blue or light blue such as sky or sea is displayed is printed. Further, in the present embodiment, a case will be described as an example where two functions of a function for selecting the color of a printing paper and a function for selecting a color conversion pattern operate according to the color information of the input image.

((1) Operation when white paper and yellow printing paper are stacked and image attributes are not determined)
First, a description will be given of color conversion control in the case where the paper feed tray 130 is provided with white paper and yellow printing paper and image attributes are not determined. 8 is a flowchart showing the processing performed by the arithmetic processing unit 330 of FIG. 2, FIG. 9 is a flowchart showing the printing paper selection processing of FIG. 8, and FIG. 10 is the image data input by the processing of FIG. FIG. 6 is an explanatory diagram illustrating a state of color change of an image to be printed from the beginning. In this case, information on the white and yellow printing papers stacked on the paper feed trays 130 (130a to 130c) is accumulated in the paper information storage unit 335. Based on this information, the profile shown in FIG. Shall be selected.

  First, when print processing is executed according to an instruction from a user, job data is input to the job data receiving unit 331. Thereafter, the job data is transmitted to the input image information acquisition unit 332, and as shown in FIG. 8, the input image information acquisition unit 332 analyzes the input image (step S101) and determines whether the image data is a monochrome image or a color for each page. It is determined whether it is an image (step S102).

  In this embodiment, since only black characters are printed on the blank page on the first page, it is determined as a monochrome image (“monochrome” in step S102), and the color information is input to the color conversion control unit 333. The color conversion pattern switching unit 333b refers to the profile, determines the color conversion pattern to be grayscale processing (step S103), and transmits the information to the image processing unit 337. In addition, the paper feed switching control unit 333a selects a blank sheet with reference to the profile (step S103), refers to the paper information included in the paper information storage unit 335, and selects the paper feed tray 130 on which the white paper is loaded. Drive control. Thereafter, the image forming unit performs monochrome printing on the white paper using the black ink head of the head unit 110 (step S104). As a result, as shown in FIG. 10, the first page of the job data generates a printed matter in which characters are printed on white paper with black ink.

  On the other hand, when it is determined that the image data is a color image (“color” in step S102), the input image information acquisition unit 332 determines monochromatic chromatic color data (step S105). In the present embodiment, since the second page to the fifth page are color images of characters or photographs, the input image information acquisition unit 332 determines the image data for the second page to the fifth page for each page. Chromatic color data is calculated (step S105). In the present embodiment, the second page includes red, magenta, blue, and green characters, but includes many magenta colors that can be reproduced by combining M (magenta) ink and white paper. Therefore, the chromatic color data is magenta.

  The third page contains red and flesh-colored photos that can be reproduced by combining red pseudo color conversion and yellow paper loaded on the paper feed tray 130, so the red and flesh-color data become chromatic color data. . The fourth page contains a magenta photograph that can be reproduced with a combination of M (magenta) ink and white paper, so the magenta color becomes chromatic color data. On the fifth page, it is not possible to distinguish whether the cyan photo of the two photos is cyan due to the influence of the background color or whether it is cyan as a photo in the first place. On the other hand, in the other blue photograph, unlike the background color, it is clear that the image of the photograph itself is blue such as the sky or the sea, so blue is the chromatic color data.

  Next, this color information is input to the color conversion control unit 333. When the color information is input, the color conversion pattern switching unit 333b selects a color conversion pattern with reference to the profile storage unit 336 (step S108). In the present embodiment, as shown in FIG. 4, since the profiles used for color conversion of the color image are all red pseudo color patterns, the red pseudo color is selected for all pages regardless of the contents of the color information. Information on the selected color conversion pattern is transmitted to the image processing unit 337.

  In parallel with the selection of the color conversion pattern by the color conversion pattern switching unit 333b (step S108), the paper feed switching control unit 333a includes the chromatic color data of each page and the chromatic color ink (magenta) used for printing. Are compared (step S106), and the printing paper to be used is selected with reference to the profile (step S107).

  Specifically, in the color conversion pattern switching unit 333b, as shown in FIG. 9, first, it is determined whether or not the monochrome chromatic color data has the same hue as the hue of the color to be used or a hue at the opposite position. Judgment is made (step S201). If the monochrome chromatic color data has the same or opposite hue as the hue of the color to be used (YES in step S201), a blank sheet is selected (step S202). On the other hand, if the hue is not the same hue or opposite to the hue of the color to be used (NO in step S201), it is determined whether or not the chromatic color printing paper approximate to the chromatic color data is stacked on the paper feed tray 130. Judgment is made (step S203).

  If chromatic color printing paper that approximates the chromatic color data is loaded on the paper feed tray 130 (YES in step S203), the color paper is selected (step S204), and the chromatic color data approximates the chromatic color data. When the chromatic printing paper is not stacked on the paper feed tray 130 (NO in step S203), white paper is selected (step S201).

  In the present embodiment, the chromatic color data of the second and fourth pages are magenta and have the same hue as the hue of the chromatic ink (magenta color) used for printing (YES in step S201). Selected (step S202).

  On the other hand, the chromatic color data on the third page is red and skin color, and the chromatic color data on the fifth page is blue, and the same or opposite hue as the hue of the chromatic ink (magenta color) used for printing. If not (NO in step S201), it is determined whether or not chromatic color printing paper that approximates the chromatic color data is stacked on the paper feed tray 130 (step S203).

  The chromatic color data on the third page is red and skin color, and includes yellow printing paper that is chromatic color printing paper that approximates the chromatic color data (YES in step S203). Selected (step S204). On the other hand, since the chromatic color data of the fifth page is blue and there is no chromatic color printing paper that approximates the chromatic color data (NO in step S203), a blank page is selected (step S202).

  Thereafter, using the image data of the second page to the fifth page, a color printing process is performed using each selected color conversion pattern and printing paper (step S109). As a result, as shown in FIG. 10, on the second page, red and magenta characters are displayed in magenta on a blank sheet, and blue and green characters are displayed in black. That is, a print result (red → magenta, blue → black, green → black) different from the image data is obtained except for magenta characters in the image data. However, the most magenta characters in the image data are reproduced in magenta color, and the blue characters are reproduced in purple including a blue component, so that the entire image has 2 (K (black) and M (magenta)). By color printing, a printing result close to image data can be obtained.

  On the third page, magenta ink is ejected onto yellow printing paper, and the photograph portion is displayed in red and flesh color. On the fourth page, magenta ink is ejected onto white paper, and the photograph portion is displayed in magenta. As a result, it is possible to obtain print results faithful to the image data for the third and fourth pages. On the fifth page, the blue part is displayed in black on the white paper, and the cyan part is displayed in gray. Thus, using white paper and two inks of K (black) and M (magenta), image data including cold-colored photographs (blue and cyan) that are different from both the paper color and the ink color. , Printing results with hues similar to those (black, gray) can be obtained.

((2) Operation when white paper and light blue printing paper are stacked and the original attribute is not determined)
Next, color conversion control in the case where the paper feed tray 130 is provided with white paper and light blue printing paper and the attribute of the image is not determined will be described. Also in this case, the processing shown in the flowcharts of FIGS. 8 and 9 is performed. FIG. 11 is an explanatory diagram showing a color change state of an image to be printed from the image data input by the processing of FIG. Here, information in which white paper and light blue printing paper are stacked on the paper feed tray 130 (130a to 130c) is accumulated in the paper information storage unit 335, and the profile shown in FIG. 5 is selected at the time of color conversion. And

  First, when print processing is executed according to an instruction from a user, job data is input to the job data receiving unit 331. Thereafter, similarly to the above, the processing shown in the flowchart of FIG. 8 is performed. Specifically, first, processing from step S101 to step S105 is performed.

  Thereafter, the color information determined in step S <b> 105 in FIG. 8 is input to the color conversion control unit 333. When the color information is input, the color conversion pattern switching unit 333b determines a color conversion pattern with reference to the profile storage unit 336 (step S108). In this embodiment, as shown in FIG. 4, all the profiles used for color conversion of a color image are blue pseudo color patterns, and therefore all pages are determined to be blue pseudo color regardless of the content of color information. Information on the determined color conversion pattern is transmitted to the image processing unit 337.

  In parallel with the determination of the color conversion pattern by the color conversion pattern switching unit 333b, the paper feed switching control unit 333a compares the chromatic color data of each page with the chromatic color ink (magenta) used for printing ( In step S106, the printing paper to be used is selected with reference to the profile (step S107).

  In step S107 of FIG. 8, the process of the flowchart of FIG. 9 is performed. Here, the chromatic color data on the 2nd and 4th pages is magenta and has the same hue as the hue of the chromatic ink (magenta color) used for printing (YES in step S201), so the blank paper is selected. (Step S202).

  On the other hand, the chromatic color data on the third page is red and skin color, and the chromatic color data on the fifth page is blue, and the same or opposite hue as the hue of the chromatic ink (magenta color) used for printing. If not (NO in step S201), it is determined whether or not chromatic color printing paper that approximates the chromatic color data is stacked on the paper feed tray 130 (step S203).

  The chromatic color data on the third page is red and skin color, and there is no chromatic color printing paper that approximates the chromatic color data (NO in step S203), so a blank paper is selected (step S202). On the other hand, the chromatic color data on the fifth page is blue, and a light blue color print paper that is a chromatic color print paper that approximates the chromatic color data is included (YES in step S203), so the light blue color paper is selected. (Step S204).

  Thereafter, using the image data of the second page to the fifth page, a color printing process is performed using each selected color conversion pattern and printing paper (step S109). As a result, as shown in FIG. 11, on the second page, blue and magenta characters are displayed in magenta on white paper, and red and green characters are displayed in black. That is, a print result (red → black, blue → magenta, green → black) different from the image data is obtained except for magenta characters in the image data. However, the most magenta characters in the image data are reproduced in magenta, warm red characters are the same warm magenta, and cold blue and green characters are cold black. Therefore, for the entire image, a printing result close to the image data can be obtained by two-color printing of K (black) and M (magenta).

  On the third page, black ink is ejected onto white printing paper, and the photo portion is displayed in monochrome. In this color printing process, as will be described later, the cyan background and photo of the fifth page are reproduced with light blue paper, and the blue photo is reproduced with purple with light blue paper and magenta ink color, It is distinguished from cyan photographs. Therefore, in this color printing process, a blue pseudo color conversion pattern is used. Therefore, the skin color and red photograph on the third page are printed in black. On the fourth page, magenta ink is ejected onto white paper, and the photograph portion is displayed in magenta. As a result, a print result faithful to the image data can be obtained for the fourth page. On the fifth page, the blue part is printed in magenta on a light blue printing paper to display purple, and the light blue part is made colorless to display the light blue of the printing paper as it is.

((3) Operation when white paper and yellow printing paper are stacked and document attributes are determined)
Next, color conversion control in the case where the paper feed tray 130 is provided with white paper and yellow printing color paper and the image attributes are determined will be described. 12 is a flowchart showing processing performed by the arithmetic processing unit 330 in FIG. 2, FIG. 13 is a flowchart showing printing sheet selection processing in FIG. 12, and FIG. 14 is image data input by the processing in FIG. FIG. 6 is an explanatory diagram illustrating a state of color change of an image to be printed from the beginning. Here, information in which white paper and yellow printing paper are stacked on the paper feed tray 130 (130a to 130c) is accumulated in the paper information storage unit 335, and the profile shown in FIG. 6 is selected at the time of color conversion. And

  First, when print processing is executed according to an instruction from a user, job data is input to the job data receiving unit 331. Thereafter, the job data is transmitted to the input image information acquisition unit 332, and as shown in FIG. 12, the input image information acquisition unit 332 analyzes the input image (step S401), and whether the image data is a monochrome image or a color for each page. It is determined whether it is an image (step S402).

  In the present embodiment, since only black characters are printed on white paper on the first page, it is determined as a monochrome image (“monochrome” in step S402), and the color information is input to the color conversion control unit 333. The color conversion pattern switching unit 333b refers to the profile, determines the color conversion pattern to be grayscale processing (step S403), and transmits the information to the image processing unit 337. In addition, the paper feed switching control unit 333a selects a blank paper by referring to the profile (step S403), and refers to the paper information included in the paper information storage unit 335 to select the paper feed tray 130 on which the white paper is stacked. Drive control. Thereafter, the image forming unit performs monochrome printing on the white paper using the black ink head of the head unit 110 (step S404). As a result, as shown in FIG. 14, the first page of the job data is a printed material in which characters are printed on black paper with black ink.

  On the other hand, when it is determined that the image data is a color image (“color” in step S402), the input image information acquisition unit 332 determines monochromatic chromatic color data (step S405). In this embodiment, since the second page to the fifth page are color images in characters or photographs, the image data from the second page to the fifth page is stored in the input image information acquisition unit 332 for each page. Color data is calculated (step S405). In the present embodiment, the second page includes characters of red, magenta, blue, and green, but since the magenta color is included, the chromatic color data is magenta.

  The third page contains red and flesh-colored photographs, so red and flesh-color are chromatic color data. On the fourth page, a magenta color photograph is included, so the magenta color becomes chromatic color data. On the fifth page, since blue such as the sky and the sea is included, blue is the chromatic color data.

  The input image information acquisition unit 332 calculates image attributes for each page (step S406). In the present embodiment, since the second page is image data of only characters, it has a character or graphic attribute, and the third, fourth, and fifth pages are photographic images because they are photographic images.

  Then, the color information of the image data including the single color chromatic color data and the attribute information is input to the color conversion control unit 333. When the color information is input, the color conversion pattern switching unit 333b selects a color conversion pattern with reference to the profile (step S409).

  In this color conversion pattern selection, as shown in FIG. 13, the attribute of the image data is determined (step S501). If the attribute is a character or a figure (“character, figure” in step S501), FIG. A chromatic / achromatic pattern as shown in (a) is selected (step S502). If the attribute of the image data is a photo (“photo” in step S501), a red pseudo color as shown in FIG. 3B is selected.

  In this embodiment, since the attributes of the second page are characters and figures, a chromatic / achromatic pattern is selected. Further, since the attribute of the third to fifth pages is a photograph, the red pseudo color is selected. The selected information is transmitted to the image processing unit 337.

  As shown in FIG. 12, in parallel with the selection of the color conversion pattern by the color conversion pattern switching unit 333b (step S409), the paper feed switching control unit 333a has the chromatic color data of each page and the presence used for printing. The color ink (magenta) is compared (step S407), and the printing paper to be used is selected with reference to the profile (step S408).

  In the present embodiment, the chromatic color data of the second and fourth pages are magenta and have the same hue as the hue of the chromatic ink (magenta color) used for printing (YES in step S201). Selected (step S202).

  On the other hand, the chromatic color data on the third page is red and skin color, and the chromatic color data on the fifth page is blue, and the same or opposite hue as the hue of the chromatic ink (magenta color) used for printing. If not (NO in step S201), it is determined whether or not chromatic color printing paper that approximates the chromatic color data is stacked on the paper feed tray 130 (step S203).

  The chromatic color data on the third page is red and skin color, and includes yellow printing paper that is chromatic color printing paper that approximates the chromatic color data (YES in step S203). Selected (step S204). On the other hand, since the chromatic color data of the fifth page is blue and there is no chromatic color printing paper that approximates the chromatic color data (NO in step S203), a blank page is selected (step S202).

  Thereafter, using the image data of the second page to the fifth page, a color printing process is performed using each selected color conversion pattern and printing paper (step S410). Thereby, as shown in FIG. 14, on the second page, all characters are displayed in magenta on a blank sheet. That is, a print result (red → magenta, blue → magenta, green → magenta) different from the image data is obtained except for magenta characters in the image data. However, since the most magenta characters in the image data are reproduced in magenta color, the entire image can be printed with two colors of K (black) and M (magenta) to obtain a print result close to the image data. Can do.

  On the third page, magenta ink is ejected onto yellow printing paper, and the photograph portion is displayed in red and flesh color. On the fourth page, magenta ink is ejected onto white paper, and the photograph portion is displayed in magenta. As a result, it is possible to obtain print results faithful to the image data for the third and fourth pages. On the fifth page, the blue part is displayed in black on the white paper, and the cyan part is displayed in gray. Thus, using white paper and two inks of K (black) and M (magenta), image data including cold-colored photographs (blue and cyan) that are different from both the paper color and the ink color. , Printing results with hues similar to those (black, gray) can be obtained.

((4) Operation when White Paper and Blue and Yellow Printing Paper are Stacked and Document Attributes are Determined)
Next, a description will be given of color conversion control when the paper feed tray 130 is provided with white paper, blue and yellow colored paper, and image attributes are determined. Also in this case, the process shown in the flowchart of FIG. 12 is performed. FIG. 15 is a flowchart showing the printing paper selection process of FIG. 12, and FIG. 16 is an explanatory view showing the color change state of an image printed from the image data input by the process of FIG. In this case, information in which white paper, blue and yellow printing paper are stacked on the paper feed tray 130 (130a to 130c) is accumulated in the paper information storage unit 335, and the profile shown in FIG. 7 is selected at the time of color conversion. Shall be.

  First, when print processing is executed according to an instruction from a user, job data is input to the job data receiving unit 331. Thereafter, the processing shown in the flowchart of FIG. 12 is performed in the same manner as described above. Specifically, first, processing from step S401 to step S406 is performed.

  Thereafter, the color information of the image data including the chromatic color data determined in step S405 and the attribute information determined in step S406 is input to the color conversion control unit 333. When the color information is input, the color conversion pattern switching unit 333b selects a color conversion pattern with reference to the profile storage unit 336 (step S409).

  In this color conversion pattern selection, as shown in FIG. 15, the attribute of the image data is determined (step S601). If the attribute is a character or a figure (“character, figure” in step S601), FIG. A chromatic / achromatic pattern as shown in (a) is selected (step S602). If the attribute of the image data is a photo (“photo” in step S601), it is determined whether the pixels included in the image data are blue (B) or red (R) (step S603). .

  When many contained pixels are blue (“blue” in step S603), a blue pseudo color is selected (step S604), and when many contained pixels are red (“red” in step S603). ), The red pseudo color is selected (step S605).

  In this embodiment, since the attributes of the second page are characters and figures, a chromatic / achromatic pattern is selected. Also, among the 3 to 5 pages whose attributes are photographs, the chromatic color data on the third page is red and skin color, and the chromatic color data on the fourth page is magenta, so the red pseudo color is selected. On the other hand, since the chromatic color data of the fifth page is blue, the blue pseudo color is selected. The selected information is transmitted to the image processing unit 337.

  As shown in FIG. 12, in parallel with the selection of the color conversion pattern by the color conversion pattern switching unit 333b (step S409), the paper feed switching control unit 333a has the chromatic color data of each page and the presence used for printing. The color ink (magenta) is compared (step S407), and the printing paper to be used is selected with reference to the profile (step S408).

  In the present embodiment, the chromatic color data of the second and fourth pages are magenta and have the same hue as the hue of the chromatic ink (magenta color) used for printing (YES in step S201). Selected (step S202).

  On the other hand, the chromatic color data on the third page is red and skin color, and the chromatic color data on the fifth page is blue, and the same or opposite hue as the hue of the chromatic ink (magenta color) used for printing. If not (NO in step S201), it is determined whether or not chromatic color printing paper that approximates the chromatic color data is stacked on the paper feed tray 130 (step S203).

  The chromatic color data on the third page is red and skin color, and includes yellow printing paper that is chromatic color printing paper that approximates the chromatic color data (YES in step S203). Selected (step S204). On the other hand, the chromatic color data on the fifth page is blue, and since the chromatic color printing paper that is similar to the chromatic color data is included (YES in step S203), the light blue printing paper is Selected (step S204).

  Thereafter, using the image data of the second page to the fifth page, a color printing process is performed using each selected color conversion pattern and printing paper (step S410). As a result, as shown in FIG. 16, on the second page, all characters are displayed in magenta on a blank sheet. That is, a print result (red → magenta, blue → magenta, green → magenta) different from the image data is obtained except for magenta characters in the image data. However, since the most magenta characters in the image data are reproduced in magenta color, the entire image can be printed with two colors of K (black) and M (magenta) to obtain a print result close to the image data. Can do.

  On the third page, magenta ink is ejected onto yellow printing paper, and the photograph portion is displayed in red and flesh color. On the fourth page, magenta ink is ejected onto white paper, and the photograph portion is displayed in magenta. As a result, it is possible to obtain print results faithful to the image data for the third and fourth pages. On the fifth page, the blue part is printed in magenta on a light blue printing paper to display purple, and the light blue part is made colorless to display the light blue of the printing paper as it is. As a result, the cyan background and photo of the fifth page are reproduced on light blue paper, and the blue photo is reproduced in purple by light blue paper and magenta ink color, distinguishing it from cyan photo. For the entire image, a printing result close to the image data can be obtained by two-color printing of K (black) and M (magenta).

  In the present embodiment, the two-color printing apparatus in which the head unit 110 has magenta and black ink heads has been described as an example. However, the present invention is not limited to this, for example, two chromatic colors. You may use for the three-color printing apparatus using an ink and an achromatic color ink. In this embodiment, the chromatic color ink is magenta. However, the present invention is not limited to this, and cyan, yellow, or red may be used.

(Action / Effect)
According to this embodiment, since the two-color printing apparatus can switch the selection of a plurality of types of printing papers having different colors based on the color information of the input image, for example, the original is a monochrome image. In this case, an inexpensive white paper can be selected, and when the original is a color image such as a photograph, a colored paper can be selected. This improves the expressive power by using colored paper only in areas where color printing is required, without specifying the page on which the user inserts colored paper, and cheap white paper is used for printed pages that do not require color. Since it can be used, the cost of the whole printed matter can be reduced. Therefore, a pseudo color image corresponding to a full color image can be acquired with low cost, effort, and high expressive power.

  In particular, the paper feed switching control unit 333a selects a chromatic color printing paper that approximates the color of the chromatic color data that is the representative color of the input image calculated from the color information of the input image. The color of the input image can be expressed by color, and a color print can be obtained without using expensive ink. Also, if the chromatic color data that is the representative color is red or flesh color, and the yellow paper is included in the print paper, the yellow paper is selected, and the magenta ink amount and yellow print are selected. With paper, the expression power of red and flesh color can be improved. As described above, according to the present embodiment, more colors can be reproduced at a low cost by automatically selecting colored paper having a different color according to color information that is representative of the input image.

  Further, when the chromatic color data calculated from the color information of the input image has the same hue as that of the chromatic ink used for printing, the paper feed switching control unit 333a selects a white printing paper. Since ink of the same color as the input image is ejected, an image of the same color as the input image can be formed with a low-cost white paper. In addition, even when the chromatic color data calculated from the color information is a hue opposite to the hue of the ink used for printing, a color close to the color of the input image cannot be expressed with the combination of the chromatic color ink and colored paper. For this reason, a blank paper is selected and printed with black ink. For this reason, a portion with low expressive power can be printed at low cost.

  Furthermore, when the chromatic color data calculated from the color information of the input image is a hue adjacent to the hue of the ink used for printing, by combining the ink used for printing with the chromatic color paper, Represents a color that approximates the color of the input image. For this reason, a color printed matter can be obtained without using expensive full-color printing.

  In this embodiment, since the color conversion pattern is switched based on the color information of the input image, for example, in an image including a color character, a chromatic / achromatic color pattern is used, and the color character that the user wants to emphasize It is possible to acquire an image reflecting all of the above. In the present embodiment, for example, when the printing paper is light blue and the image color information includes light blue, the light blue portion of the image data is set to be colorless. Make fine adjustments with. For this reason, the color of the printing paper can be effectively used to express the color of the image, and the printed matter intended by the user can be provided while suppressing the printing cost.

  Furthermore, in the present embodiment, an ink jet printing apparatus that performs two-color or three-color pseudo color printing using an achromatic color ink and a chromatic color ink has been described as an example. However, the present invention is not limited to this, and the present invention is widely applicable to various image forming apparatuses that form pseudo color images using achromatic and chromatic recording materials by methods other than inkjet, such as electrophotographic methods and stencil printing methods. Applicable.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the first embodiment described above, the color conversion pattern switching unit 333b sets the amount of recording material to 0 for the image portion having color information that approximates the color information of the selected recording medium in the input full-color image data. As shown in FIG. However, in the second embodiment, at the time of this color conversion process, the color information of the selected printing paper is further obtained for the conversion target area including any one of the edge of the character, the outline of the image, or the point in the image portion. A case will be described in which printing processing is performed by substituting pixels with color information different from the above. In the present embodiment, a case where only a light blue printing paper is loaded on the printing apparatus and a color conversion pattern of a red pseudo color is used for the color image will be described as an example.

  FIG. 17 is a block diagram showing an internal structure of the arithmetic processing unit 330 according to the second embodiment of the present invention, and FIG. 18A shows an edge extraction processing filter processed by the edge extraction unit of FIG. FIG. 18B is an explanatory diagram showing a state in which a filter is arranged on the image data. FIGS. 19A and 19B are explanatory diagrams of color profiles stored in the profile storage unit of FIG. In the present embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the functions and the like are the same unless otherwise specified, and the description thereof is omitted.

  In the present embodiment, the color conversion control unit 333 determines the presence / absence of the replacement process, and the color conversion control unit 333 determines the presence / absence of the replacement process based on the profile stored in the profile storage unit 336. . This profile data is different from that of the first embodiment in that the image processing unit 380 includes a condition as to whether or not to perform a replacement process. Here, an example of the profile stored in the profile storage unit 336 is shown in FIGS.

  The profile shown in FIG. 19A is profile data when only white paper is stacked on the paper feed tray 130 and a color image is printed in two colors with black and magenta inks. In this profile data, the printing paper is set so that all blank paper is selected and the red pseudo color is selected when the input image data is a color image.

  Further, the profile shown in FIG. 19B is profile data when two-color printing is performed on black and magenta inks with only light blue printing paper loaded on the paper feed tray 130. In this profile data, all the printing paper is set to light blue, and when the input image data is a color image, red pseudo color is selected.

  In the profile data shown in FIGS. 19A and 19B, presence / absence of replacement processing is further set. In this replacement process, the color information of the selected paper is compared with the color information of the input image, and the color information of the input image that approximates the color information of the print paper is determined to execute the replacement process. It is determined that the replacement process is not executed for the color information of the input image that does not approximate the color information. Specifically, as shown in FIG. 19A, when the printing paper is an achromatic blank paper, the color information (red, flesh, light blue, blue, green, etc.) of the input image is printed. Since it does not approximate the color of the paper, it is determined that the replacement process is not executed.

  Next, as shown in FIG. 19B, when the printing paper is a chromatic light blue printing paper, the color information of the input image is the color of the hue adjacent to the ink color (magenta). The red or flesh color located in the counterclockwise direction on the hue circle with respect to the ink color does not approximate the color of the printing paper (light blue), so it is determined that the replacement process is not executed. Also, the color information of the input image is not similar to the color of the printing paper (light blue) for green, which is the hue located in the opposite direction to the ink color (magenta) used for printing the input image. It is determined that the process is not executed. On the other hand, the color information of the input image is a hue adjacent to an ink color (magenta) in which monochrome chromatic color data is used, and the blue color positioned in the clockwise direction on the hue ring with respect to the ink color is Since it approximates the color (light blue) of the printing paper, it is determined that the replacement process is executed. The determination result is input to the image processing unit 380, and the image processing unit 380 performs a replacement process.

  As shown in FIG. 17, the image processing unit 380 includes a color conversion circuit 381 and an image formation control unit 384. The color conversion circuit 381 is a circuit that performs color conversion of an input image in accordance with the control of the color conversion control unit 333, and includes an edge extraction unit 382 and a composition processing unit 383. The edge extraction unit 382 and the composition processing unit 383 function as a replacement processing unit. Here, when the color conversion circuit 381 acquires the signal of the replacement process from the color conversion pattern switching unit 333b, the image having color information that approximates the color information of the selected printing paper among the RGB print images. The portion is input to the edge extraction unit 382 without changing the color information of the image data. On the other hand, for an image portion having color information that does not approximate the color information of the selected printing paper, the color conversion circuit 381 refers to the color conversion pattern and converts each color of RGB to M (magenta) and K (black). Color conversion is performed so as to express with ink. Then, the image data is input to the composition processing unit 383.

  The edge extraction unit 382 is a module that extracts a conversion target region including any one of a character edge, an image outline, and a point from an image portion having color information approximate to the color information of a selected printing paper. The edge extraction unit 382 includes an achromatic color edge extraction unit 382b and a chromatic color edge extraction unit 382a. Here, one of the achromatic color edge extraction unit 382b and the chromatic color edge extraction unit 382a only needs to execute processing, and the conversion target area is printed based on the control signal of the color conversion pattern switching unit 333b. It is appropriately selected according to the ink color information. In the present embodiment, it is assumed that the conversion target area is set to perform printing processing with achromatic K ink, and the achromatic color edge extraction unit 382b executes processing.

The chromatic color edge extraction unit 382a and the achromatic color edge extraction unit 382b use the filter F as shown in FIG. 18A to convert the pixel E in the image to the target pixel E1 as shown in FIG. 18B. Are sequentially selected, and it is determined from the difference between the pixel value of the target pixel E1 and the pixel values of the peripheral pixels (pixels included in the filter F) whether or not the target pixel portion is the conversion target region. Specifically, pixels having color information similar to the color information of the printing paper in the image data are sequentially selected as the target pixel E1, and the central portion F1 of the filter is arranged at the target pixel E1. And the following formula: predetermined threshold ≧
| (Pixel value of the central portion F1 of the filter F × 8)
-(Total pixel value in other filters (8 squares)) |
As shown in FIG. 4, the total pixel value in the other filter is subtracted from the pixel value obtained by multiplying the pixel value of the central portion by 8 and it is determined whether or not the absolute value of the subtracted value is equal to or greater than a predetermined threshold value. To do.

  When the absolute value of the subtraction value is equal to or greater than a predetermined threshold value, the target pixel E1 is determined to be a conversion target region. On the other hand, when the absolute value of the subtraction value is less than the predetermined threshold value, it is determined that the target pixel E1 is a non-conversion target region. The image data of the conversion target area extracted by the edge extraction unit 382 is color-converted into pixels having color information different from the color information of the selected printing paper by the function of the color conversion circuit 381, and is input to the synthesis processing unit 383. The In the present embodiment, since the conversion target area is set to perform printing processing with achromatic K ink, color conversion is performed to black pixels. On the other hand, the image data of the non-conversion target area is subjected to color conversion processing by the function of the color conversion circuit 381 so that the amount of recording material is 0 and becomes colorless on printing, and is input to the image formation control unit 384.

  The composition processing unit 383 is a module that synthesizes the image data in the conversion target area and the image data that has been color-converted into an achromatic color or a chromatic color by the color conversion circuit 381. The synthesis processing unit 383 includes a chromatic color synthesis unit 383a and an achromatic color synthesis unit 383b. Here, either one of the chromatic color synthesis unit 383a and the achromatic color synthesis unit 383b only needs to execute processing, and color information for printing the conversion target area based on the control signal of the color conversion pattern switching unit 333b ( The chromatic color or the achromatic color) is appropriately selected.

  In this embodiment, since the conversion target area is color-converted to black pixels, the image data that has been achromatic-color-converted is selected and combined with the image data of the replacement target area. Then, the composition processing unit 383 inputs the image data that has undergone the composition processing (exchange target region and achromatic color image data) and the image data that has not undergone the composition processing (chromatic color image data) to the image formation control unit 384. To do.

  The image formation control unit 384 is a module that controls the driving of the ink heads of the respective colors and controls the entire image formation processing. In the present embodiment, the image formation control unit 384 controls the ink head 110 based on the image data that has been combined, the image data that has not been combined, and the image data of the non-conversion target area. Control is performed to eject ink and form a printed image. In this embodiment, as shown in FIGS. 19A and 19B, a description is given using a profile in which a light blue printing paper is stacked on a printing paper and a red pseudo color is uniformly selected for a color image. did. However, the present invention is not limited to this and can be modified as appropriate. For example, in the profile using two or more types of printing paper and a plurality of color conversion patterns as shown in the first embodiment, it may be configured to determine whether or not a replacement process is performed.

(Replacement operation)
Next, the replacement processing operation in the printing apparatus having the above configuration will be described. FIG. 20 is a flowchart showing the replacement process of FIG. This replacement processing operation is executed during the printing operations in step S109 and step S410 in the first embodiment. Here, a case where only light blue printing paper is loaded on the printing apparatus, a red pseudo color color conversion pattern is used for the color image, and the conversion target area portion is printed with achromatic ink will be described as an example. To do.

  First, the color conversion control unit 333 compares the color information of the selected printing paper with the color information of the input image (step S701), and the input image that approximates the color of the selected chromatic printing paper is selected. It is determined whether there is color information (step S702). If there is no color information of the input image that approximates the color of the selected chromatic printing paper (NO in step S702), it is determined not to perform the replacement process (step S703), and two-color printing is performed as usual. This is performed (step S708). On the other hand, if there is color information of the input image that approximates the color of the selected chromatic color printing paper (YES in step S702), it is determined that the replacement process is to be executed, and the operation signal for the replacement process is sent to the image processing unit 380. To enter.

  In the image processing unit 380, first, the color conversion circuit 381 extracts an edge of an RGB print image that has color information that approximates the color information of the selected printing paper, while maintaining the color information of the image data. Input to the unit 382. On the other hand, for an image portion having color information that does not approximate the color information of the selected printing paper, the color conversion pattern switched by the color conversion pattern switching unit 333b is referred to, and each color of RGB is set to M (magenta) and K. Color conversion is performed so as to express with (black) ink. Then, the image data is input to the composition processing unit 383.

  As shown in FIG. 18B, the achromatic color edge extraction unit 382b uses the filter F as shown in FIG. 18A for an image portion having color information approximate to the color information of the printing paper. The middle pixel E is sequentially selected as the target pixel E1, and a conversion target area including any one of the edge of the character, the contour of the image, or the point is extracted (step S704). The extracted image data of the conversion target area is color-converted into achromatic pixels having color information different from the color information of the selected printing paper by the function of the color conversion circuit 381 (step S705), and the composition processing unit It is input to 383.

  On the other hand, the image data in the non-conversion target area is color-converted by the function of the color conversion circuit 381 so that the image data in the non-conversion target area becomes colorless on printing with the amount of recording material set to 0 (pixel value = 0). Processed (step S706) and input to the image formation control unit 384.

  Next, the composition processing unit 383 performs composition processing on the color-converted image data of the conversion target area and the image data color-converted to an achromatic color in the color conversion circuit 381 (step S707), and combines the image data. Is input to the image formation control unit 384. In addition, the image formation control unit 384 controls the driving of the ink heads 110 for each color based on the image data that has been combined, the image data that has not been combined, and the image data in the non-conversion target area. A print image is formed (step S708).

(Action / Effect)
According to this embodiment, when an original color that cannot be expressed by two-color printing is expressed by the color of the selected chromatic color printing paper without ejecting ink onto the printing paper, An outline, a point, and the like of the image are extracted as a conversion target region, and the conversion target region is color-converted into an ink color (for example, black ink or magenta ink) to be printed. Thus, for example, when characters or clouds are represented in the sky image data, the edge of the characters and the outline portion of the cloud image can be printed, so the color of the printing paper Can be expressed without losing image data information.

DESCRIPTION OF SYMBOLS 3 Network 100 Inkjet printing apparatus 110 Head unit 120 Side paper feed tray 130 Paper feed tray 130a-130c Tray 140 Paper discharge port 150 Paper discharge stand 160 Conveyance belt 161 Drive roller 162 Driven roller 170,172 Switching mechanism 183 Conveyance roller 200 User terminal 330 Arithmetic Processing Unit 331 Job Data Receiving Unit 332 Input Image Information Acquisition Unit 333 Color Conversion Control Unit 333a Paper Feed Switching Control Unit 333b Color Conversion Pattern Switching Unit 334 Paper Color Information Acquisition Unit 335 Paper Information Storage Unit 336 Profile Storage Unit 337 Image Processing Section 337a Image formation control section 337b Color conversion circuit 340 Operation panel 350 Paper detection mechanism 360 Communication interface 370 Paper transport means 380 Image processing section 381 Color conversion circuit 382 Edge extraction unit 382b Achromatic edge extraction unit 383 Compositing processing unit 383a Chromatic color synthesis unit 383b Achromatic color synthesis unit 384 Image formation control unit CR Normal path DR Paper discharge path FR Paper feed System transport path R Registration part SR Reverse path

Claims (7)

The input full-color image data is color-converted, and based on the color-converted full-color image data, one or two kinds of chromatic recording materials and an achromatic recording material are used by the image forming means, An image forming apparatus that performs image formation of a pseudo color image including two-color printing on a recording medium,
Paper feeding means for selectively supplying a plurality of color recording media to the image forming means;
Of the chromatic colors present in the full-color image data, a color that can reproduce an approximate color in the pseudo-color image, and the occupation area ratio for the full-color image is a predetermined value or more, or a predetermined designated color Image color information acquisition means for acquiring one or a plurality of representative colors and acquiring color information including data of the representative colors;
Based on the color information, as a recording medium to be used for forming the pseudo color image, a recording medium having a color corresponding to the acquired color information is selected and fed to the image forming unit. Paper feed control means for controlling the paper feed means;
An image forming apparatus comprising:   The color information includes attribute data of the full-color image, and chromatic color conversion ranges used for forming the pseudo color image are mutually used as color conversion patterns used for color conversion of the full-color image data. Color conversion selecting means for selecting a color conversion pattern corresponding to the color information from among a plurality of different color conversion patterns, and color conversion for color-converting the input full-color image data using the selected color conversion pattern The image forming apparatus according to claim 1, wherein the image color information acquisition unit acquires the color information including attribute data of the full color image.   Paper color information acquisition means for acquiring information relating to colors of the recording medium that can be selected by the paper supply means is further provided, and the paper supply control means uses a recording medium having a color different from the representative color as the image forming means. The image forming apparatus according to claim 1, wherein the sheet feeding unit is controlled to feed the sheet.   The paper feed control means selects a white recording medium when the representative color has the same or opposite hue as the chromatic color constituting the pseudo color image, and the representative color of the chromatic color constituting the pseudo color image. 4. The image forming apparatus according to claim 3, wherein a chromatic recording medium is selected in the case of adjacent hues.   The image forming apparatus according to claim 3, wherein the sheet feeding control unit selects a chromatic recording medium that approximates the representative color. Paper color information acquisition means for acquiring information on the color of the recording medium that can be selected by the paper supply means is further provided, and the paper supply control means records chromatic colors that are similar to the representative color unlike the representative color. controls said feeding means to feed a medium to the image forming means, before Symbol color converting means, among the input the color image data, approximate to the color information of the selected said recording medium The image forming apparatus according to claim 2 , wherein an image portion having color information is subjected to color conversion processing so that the amount of recording material is set to 0 and becomes colorless on printing.   Extracting a conversion target area including any one of a character edge, an image outline, or a point from the image portion having color information approximate to the color information of the selected recording medium, and extracting the conversion target area The image forming apparatus according to claim 6, further comprising a replacement processing unit that replaces a pixel having color information different from color information of the selected recording medium.

Images