JP2007160896A - Inkjet recording method, inkjet recording system, and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recorder which enables a high-speed output without decreasing a recording quality of character information even when an image including the character information is recorded to both faces, and to provide an inkjet recording method. <P>SOLUTION: When both-face recording is set, it is judged whether or not information other than the character information is included in the image. Multi-valued density data after a color conversion process to the information other than the character information is made a low level in comparison with multi-valued density data after color conversion to the character information. An application amount of ink is reduced thereby for graphics and images while a standard density is kept for only character parts, and the ink is fixed in a short time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inkjet recording method, an inkjet recording system, and an inkjet recording apparatus that form images on both sides of a recording medium. In particular, the present invention relates to an ink jet recording method capable of suppressing as much as possible the adverse effects that occur when a recording operation is performed with ink unfixed while maintaining character quality and recording speed.

  Various recording methods are known for the recording apparatus, but an ink jet method using a recording head that discharges ink as droplets is particularly useful in recent years.

  FIG. 1 is a perspective view for explaining a schematic configuration of a serial type ink jet recording apparatus. In the figure, reference numeral 4 denotes a recording head, which can eject a plurality of colors of ink.

  Before the start of recording, the carriage 7 on which the recording head 4 is mounted is located at the home position. When the recording start command is received, the carriage 7 moves in the arrow C direction (main scanning direction), and the recording head 4 ejects ink toward the recording medium S at a predetermined timing. When the recording for one scanning is completed, the recording roller S is conveyed in the direction of arrow A by a predetermined amount by rotating the conveying roller 1. Thereafter, the recording head 4 performs recording in the direction of arrow C again. An image is formed on the recording medium S by repeating the above-described one-time recording scanning and a predetermined amount of conveying operation.

  The recording medium S during recording is conveyed while being sandwiched and stretched by two pairs of rollers such as a conveying roller 1, a pinch roller 2 that follows the conveying roller 1, and a discharge roller 12 and a spur 13 that is linked to the discharging roller 12. Has been. When the image formation for one page is completed, the recording medium is discharged out of the apparatus by the discharge roller 12.

  By the way, in recent years, the use of recording apparatuses has been diversified, and the demand for so-called double-sided recording in which images are formed on both sides of a recording medium is increasing. Many such recording apparatuses have already been provided. In an inkjet recording apparatus that automatically realizes double-sided recording, after recording on one side of a recording medium is completed, the recording medium is re-feeded in the apparatus (direction B) without being discharged. Then, after reversing the front and back of the recording medium by the reversing means 16 provided in the apparatus, the recording medium is conveyed again to the recording area of the recording head in order to perform recording on the other side.

  For example, in the configuration of FIG. 1, the recording surface immediately after recording is fed to the reversing unit 16 while being in contact with the pinch roller 2. However, at this time, if the ink on the recording surface is insufficiently fixed, unfixed ink may be transferred to the pinch roller 2 or the like, and may be further transferred / contaminated to the reversed recording medium. In addition, when such double-sided recording is continuously performed on a number of recording media, the recording surfaces to which ink is applied are stacked on a discharge tray (not illustrated) in contact with each other. At this time, if either side of the ink is insufficiently dried, there is a problem that the recording surfaces of each other are stained.

  In order to cope with the above problem, in an inkjet recording apparatus that performs double-sided recording, after recording on one side is completed, the recording medium is held while holding, and the recording is performed after a period of time that is considered to be fixed. A method of refeeding the medium in the B direction is generally employed. Such a recording method is disclosed in Patent Document 1, for example.

  However, when the method described in Patent Document 1 is adopted, a large amount of time is consumed due to the influence of the standby time, and there is a problem that the output time is rather delayed as compared with single-sided recording. Double-sided recording is often performed for the purpose of low-cost and high-speed output, and it is not a preferable situation that the recording speed is unnecessarily slow for double-sided recording.

  For this reason, a method of reducing the amount of ink to be recorded so that the drying time can be shortened is also employed during double-sided recording (for example, Patent Document 2). According to this method, signals given to individual pixels are converted in a direction to suppress the amount of ink applied at the stage of image processing. Since the output recorded matter has a reduced ink amount compared to the case of normal single-sided recording, the drying time is shortened accordingly. As a result, the standby time from the completion of the recording on the front surface to the start of the recording on the back surface is shortened, and an improvement in the recording speed during double-sided recording can be expected.

JP-A-6-134982 JP 07-314734 A

  However, in the above method, since the signal values of all the pixels are uniformly reduced, the density of the entire image is lowered. In such cases, graphic images such as graphs and illustrations, and image images such as landscapes and portraits are often not a problem, but in character images with information, it is difficult to read and the information itself. The deficiency was once again viewed as a problem.

  The present invention has been made to solve the above problems, and the object of the present invention is to reduce the recording quality of character information, even when double-sided recording of an image including character information, An object of the present invention is to provide an ink jet recording apparatus capable of high-speed output.

  Therefore, in the present invention, in an inkjet recording method for forming an image using a recording head that discharges one or more colors of ink, a step of setting whether to record an image on both sides of a recording medium; A step of determining whether or not information other than character information is included, and a first conversion step of converting multi-value luminance data of individual pixels constituting the image into multi-value density data corresponding to ink color And a second conversion step of converting the multi-value density data into binary data, and a step of ejecting ink from the recording head based on the binary data, and duplex recording is set in the setting step. The multi-value density data after the first conversion step when it is determined that information other than character information is included in the determination step is determined not to include information other than character information. Compared to multi-value density data after the first conversion step in which, characterized in that it is a low level.

  Also, in an ink jet recording method for forming an image using a recording head that discharges one or more colors of ink, a step for setting whether or not to record an image on both sides of a recording medium, and double-sided recording is set by the setting step And a step of detecting an amount of information other than character information included in the image, a step of comparing an amount of information other than the character information with a predetermined threshold, and the individual constituting the image A first conversion step of converting multi-value luminance data of a pixel into multi-value density data corresponding to an ink color; a second conversion step of converting the multi-value density data into binary data; and the binary data A step of ejecting ink from the recording head based on the first conversion step when the amount of information other than the character information is determined to be larger than the threshold in the comparison step. Density data is compared to the multi-value density data when the amount of information other than the character information is determined to less than the threshold value, characterized in that it is a low level.

  Also, in an ink jet recording method for forming an image using a recording head that discharges one or more colors of ink, a step for setting whether or not to record an image on both sides of a recording medium, and double-sided recording is set by the setting step A step of determining whether or not each pixel constituting the image is a pixel constituting a character, and multi-value luminance data of the individual pixel is converted into a multi-value density corresponding to an ink color. A first conversion step for converting into data, a second conversion step for converting the multi-value density data into binary data, and a step of ejecting ink from the recording head based on the binary data, The multi-value density data after the first conversion step of the pixel determined not to constitute the character information in the determination step is the multi-value when the pixel is determined to be the pixel constituting the character information. Compared to the density data, and characterized by a low level.

  Further, in an ink jet recording system that forms an image using a recording head that ejects one or more colors of ink, means for setting whether to record an image on both sides of the recording medium, and information other than character information in the image A first conversion means for converting multi-value luminance data of individual pixels constituting the image into multi-value density data corresponding to ink color, and the multi-value. A second conversion unit that converts density data into binary data; and a unit that ejects ink from the recording head based on the binary data. When double-sided recording is set in the setting step, The multi-value density data after the first conversion step when it is determined that information other than character information is included in the determination step is the first value when it is determined that information other than character information is not included. Compared to multi-value density data after the conversion step, characterized in that it is a low level.

  Furthermore, in an inkjet system that forms an image using a recording head that discharges one or more colors of ink, a unit that sets whether to record an image on both sides of a recording medium, and double-sided recording is set by the setting step. Means for detecting the amount of information other than the character information included in the image, means for comparing the amount of information other than the character information with a predetermined threshold, and the individual pixels constituting the image Based on the binary data, first conversion means for converting the multi-value luminance data of the multi-value density data into multi-value density data corresponding to the ink color, second conversion means for converting the multi-value density data into binary data, And a means for ejecting ink from the recording head, and when the amount of information other than the character information is determined to be larger than the threshold in the comparison step, Density data is compared to the multi-value density data when the amount of information other than the character information is determined to less than the threshold value, characterized in that it is a low level.

  Furthermore, in an inkjet recording system that forms an image using a recording head that discharges one or more colors of ink, means for setting whether or not to record an image on both sides of a recording medium, and double-sided recording by the setting step When set, means for determining whether or not each pixel constituting the image is a pixel constituting a character, and multivalued luminance data of each individual pixel is represented by a multivalue corresponding to an ink color First conversion means for converting into density data; second conversion means for converting the multi-value density data into binary data; and means for ejecting ink from the recording head based on the binary data; When the multi-value density data after the first conversion step of the pixel determined not to constitute the character information in the determination step is determined to be a pixel constituting the character information Compared to the multi-value density data, characterized in that it is a low level.

  According to the present invention, while the standard density is maintained only in the character portion, the amount of ink applied is reduced in graphics and images, and the ink is fixed in a short time. As a result, even if double-sided recording is performed, it is possible to output the recorded matter at high speed without contaminating the inside of the recording apparatus or other recorded matter and without deteriorating the character quality.

(First embodiment)
Specific embodiments relating to the present invention will be described below. In the present embodiment, the ink jet recording apparatus shown in FIG. 1 is applied.

  FIG. 2 is a block diagram for explaining an ink jet recording system including the ink jet recording apparatus of the present embodiment and a main apparatus connected to the recording apparatus and responsible for main image processing.

  A recording apparatus main control unit 101 controls the entire recording apparatus. The recording apparatus main control unit 101 includes an MPU, a ROM, a RAM, and the like. Reference numeral 107 denotes a system bus for the control mechanisms of the printing apparatus to communicate with each other. Reference numeral 105 denotes a recording apparatus I / F unit which receives image data transmitted from the main apparatus I / F unit 109. The recording apparatus main control unit 101 temporarily stores the received data in the data buffer 106 and performs processing specific to the recording apparatus. The processed data is accumulated in the recording buffer 102 as raster data for ejection by individual recording elements provided in the recording head 4.

  Reference numeral 104 denotes a paper supply / discharge motor control unit that feeds, conveys, and discharges the recording medium. In the recording apparatus of the present embodiment, double-sided recording on a recording medium can be performed, and the paper supply / discharge motor control unit 104 includes a mechanism for transporting the recording medium in a direction opposite to the transporting direction during recording, It also controls the mechanism for automatically reversing the front and back surfaces. Reference numeral 113 denotes a carriage motor control unit that performs control when the carriage 7 on which the recording head 4 is mounted is moved and scanned in the main scanning direction. The recording apparatus main control unit 101 conveys the recording medium by controlling the paper supply / discharge motor control unit 104, and scans the recording head 4 in the main scanning direction by controlling the carriage motor control unit 113. At this time, according to the raster data stored in the recording buffer 102, ink is ejected from the recording head 4, thereby forming an image for one line on the recording medium.

  On the other hand, 108 is a main device main control unit that controls the entire main device. The main device main control unit 108 includes an MPU, a ROM, a RAM, and the like. The main device 112 is a system bus for each control mechanism to communicate with each other. In the ink jet recording system of the present embodiment, the main device performs main image processing on an image to be recorded. The main apparatus main control unit 108 transfers the image data processed in the main apparatus to the I / F unit 105 of the ink jet recording apparatus via the main apparatus I / F unit 109. In the ink jet recording system of this embodiment, a user interface is provided in the main device. For this reason, the main apparatus has a display unit 110 for notifying the user of the type of recording method and the recording status, and an operation for the user who has confirmed the display to set a recording mode or input a recording start command. A portion 111 is provided. The display unit 110 may be anything that can display information, such as a CRT. The operation unit 111 may be anything that can input information, such as a mouse or a keyboard.

  FIG. 3 is a flowchart for explaining the flow of image processing performed in the inkjet recording system of the present embodiment. After the recording quality, double-sided recording or single-sided recording, the type of recording medium, etc. are set by the user, when a recording start command is input from the operation unit 111, the main apparatus main control unit 108 is designated. The processing for the received image data is started.

  First, in step S201, the image data is subjected to color correction processing. Specifically, the red (R), green (G), and blue (B) multi-tone luminance data possessed by each pixel is within a color gamut that can be expressed by the recording apparatus by using a three-dimensional LUT or the like. To multi-gradation luminance data (R, G, B).

  In the subsequent step S202, the individual image data is converted into density signals for the four colors of ink that the printing apparatus has. Since the recording apparatus of the present embodiment includes black, cyan, magenta, and yellow inks, for example, RGB luminance data expressed in 256 gradations is converted into CMYK density data that is also expressed in 256 gradations. Converted. The density data of each pixel obtained at this time can be almost regarded as the amount of ink applied to the pixel.

  In the next step S203, multi-value error diffusion processing is performed on the density data separated into four colors. In the multilevel error diffusion according to the present embodiment, the data Y, M, C, and K of 256 gradations for each color after the four-color separation processing is performed are converted into data of 5 gradations (5 levels). The converted five-level data is data indicating an arrangement pattern in the subsequent index expansion process.

  The image data is stored in the data buffer in the recording device via the main device I / F unit 109 and the recording device I / F unit 105 in the state of the data of five levels for each color. Subsequent index expansion processing in step S204 is performed by the recording apparatus main control unit 101 in the recording apparatus.

  In the multi-value error diffusion process described above, the number of gradation levels is reduced from 256-value multi-value density information to 5-value gradation value information. However, the data that can be actually recorded by the recording head 4 is binary data indicating whether or not to record ink dots. Therefore, in the index expansion process, a dot arrangement pattern corresponding to the gradation value of each pixel is assigned to each pixel expressed by gradation levels 0 to 4 that are output values from the multi-level error diffusion process. As a result, whether or not ink dots are recorded (dot on / off) is defined in each of a plurality of areas in one pixel, and 1-bit binary data of “1” or “0” is stored in each area in one pixel. Deploy. Here, “1” is binary data indicating dot recording, and “0” is binary data indicating non-recording.

  FIG. 4 shows output patterns for input levels 0 to 4 that are converted by the index expansion processing of this embodiment. Each level value shown on the left side of the figure corresponds to level 0 to level 4, which are output values from the main device. An area composed of 2 vertical areas × 4 horizontal areas arranged on the right side corresponds to an area of one pixel output in the index expansion process. Each area in one pixel corresponds to a minimum unit in which dot on / off is defined. Note that in this specification, the “pixel” is a minimum unit that can express gradation, and is a minimum unit that is an object of image processing of multi-bit multi-bit data.

  In the figure, the area filled with a circle indicates an area where dots are recorded, and the number of dots to be recorded increases by one as the number of levels increases. The vertical direction is the direction in which the ejection ports of the recording head are arranged, and the horizontal direction is the scanning direction of the recording head. In the present embodiment, the density information of the original image is finally reflected in such a form.

  At the stage where the index development process described above is completed, all dot arrangement patterns on the recording medium are determined, and all image processing is completed. The processed binary data is stored in the recording buffer 102 as raster data that can be recorded by the recording head 4.

  In the present embodiment, the processing method of the image processing performed in step S201 or step S202 is varied based on whether double-sided recording is performed. In addition, when double-sided recording is performed, the processing method of image processing is made different for each pixel by detecting the attribute of each pixel.

  FIG. 5 is a schematic diagram for explaining image data attribute determination processing. The main apparatus of this embodiment can classify each pixel of an image to be recorded into three types depending on whether it is a character attribute, an image attribute, or a graphic attribute. In this case, the character attributes include general character information. The image attribute includes a picture such as a landscape or a human figure, an image captured in an application, and the like. Furthermore, the graphic attributes include tables, graphs, graphic images created on the application, and the like. When the image to be recorded is indicated by 301, the main apparatus classifies the image into a character attribute 302, an image attribute 303, and a graphic attribute 304. Thus, each pixel arranged at each position of the image belongs to one of the above three attributes. Such classification of attributes may be performed by an application or may be performed by printer driver software installed in the main apparatus.

  In this embodiment, before performing the series of image processing described with reference to FIG. 3, it is determined whether or not double-sided recording is performed and whether or not a character attribute is included in the image, and the image is determined according to the determination result. The processing method is different.

  FIG. 6 is a flowchart for explaining a determination process performed by the main apparatus main control unit in order to set the image processing method. First, in step S401, the main apparatus main control unit 108 analyzes the header portion of the image data. Information such as recording quality, whether or not double-sided recording is performed, the type of recording medium, and the number of recordings set by the user according to the screen of the display unit 110 is given to the header portion.

  In step S402, it is determined whether or not the current recording is double-sided recording. If it is determined that the recording is not duplex printing, the process proceeds to step S403, and standard color processing is performed. In the standard color processing in step S403, the series of image processing described with reference to FIG. 3 is performed using a normal table and normal parameters.

  On the other hand, if it is determined that double-sided recording is performed in step S402, the process proceeds to step S404, where it is determined whether data other than character attributes is included in the image data. If it is determined that data other than the character attribute is not included, that is, if it is determined that all data has the character attribute, the process proceeds to step S405, and standard color processing similar to step S403 is performed. In other words, in the present embodiment, it is determined that it is not necessary to reduce the ink application amount even for double-sided recording if the data is only character information.

  Normally, in a character image, the amount of ink applied to pixels included in the character itself is high, but almost no ink is applied to the periphery thereof. It has been empirically confirmed that even if there is a region where the amount of applied ink is locally high, no adverse effect is caused during double-sided recording. On the other hand, reducing the amount of ink applied to the character portion results in a deterioration in character quality than expected. Therefore, in the present invention, even in double-sided recording, image processing is performed so as not to reduce the ink application amount of the character portion but only the ink application amount of the graphic or image portion.

  When it is determined in step S404 that there is information other than the character attribute, the process proceeds to step S406, and duplex color processing is performed. In the double-side color processing, the series of image processing described with reference to FIG. 3 is performed, but for color correction and four-color separation processing, tables and parameters different from those used in step S403 and step S405 are prepared. Has been.

  FIG. 7 is a flowchart for explaining each step of the duplex color processing performed in step S406 in units of pixels. When the color processing for both sides is started, the attribute of each pixel is determined (step S501). Here, when the attribute of the pixel of interest is a character, standard color correction (step S502) and standard four-color separation (step S503) having the same contents as those applied in the standard color processing are executed.

  On the other hand, if it is determined in step S501 that the attribute is not a character attribute, that is, if it is determined that the attribute is a graphic or an image, the color correction for both sides (step S504) and the four-color separation for both sides differ from the standard color processing. (Step S505) is executed. The multivalued data after the color correction for both sides (step S504) and the four-color separation for both sides (step S505) are performed after the standard color correction (step S502) and the standard four-color separation (step S503) are performed. It is output at a lower level than multi-value data.

  The multi-value data separated in four colors in step S503 or step S505 is subjected to multi-value error diffusion processing in step S506, and index expansion processing is performed in step S507. In the multi-value error diffusion processing and index processing, similar signal value conversion is performed regardless of the attribute of the target pixel. The double-sided color processing is thus completed.

  In the double-sided recorded image subjected to the image processing described above, the ink application amount, that is, the density is reduced in the graphic or image while maintaining the standard density only in the character portion. As a result, in the recorded matter immediately after recording, the ink is fixed in a shorter time than when the applied amount is not reduced. As a result, even if the double-sided recording is automatically performed, the recorded material can be output at high speed without contaminating the inside of the recording apparatus or other recorded material, and without deteriorating the character quality.

(Second Embodiment)
In the first embodiment, the description has been given of the content of determining the attribute of each pixel when double-sided recording is designated. However, depending on the processing capability of the main device, or depending on the balance between the processing speed of the main device and the recording speed of the recording device, there is a concern that it may take too much time for attribute determination and table switching for each pixel. In this embodiment, even in such a case, a method for outputting character information at high speed and high quality with a relatively simple algorithm will be described.

  Also in this embodiment, the ink jet recording apparatus and the recording system shown in FIGS. 1 and 2 are used. However, in the recording system of the present embodiment, double-sided color correction and double-sided four-color separation are performed on all pixels when it is determined in step S404 shown in FIG. 6 that information other than characters is included. To be By doing so, it is not necessary to determine the attributes for all the pixels or to change the processing method to be applied. Therefore, it is possible to perform processing at higher speed than in the first embodiment.

  However, if it is determined in step S404 that information other than characters is included, if all color processing for both sides is performed, there is a concern that the original purpose of the present invention cannot be achieved. . In such a case, in step S404, a data area (area or number of pixels) other than the character attribute may be detected, and the process may proceed to step S406 only when a predetermined threshold or more exists. In this way, standard color processing is performed on the entire image for image data in which characters are dominant, and double-sided color processing is performed on the entire image for image data in which data other than characters is dominant.

  In the embodiment described above, an inkjet recording apparatus that records an image using four colors of cyan, magenta, yellow, and black has been described as an example. However, the present invention is not limited to such a configuration. . For example, in recent years, many inkjet recording apparatuses that use light cyan or light magenta with a color material density set lower than cyan or magenta simultaneously with the other four colors are also provided. In the case of such a recording apparatus, color separation processing performed after color correction is also separated into six colors instead of four colors. Even in such a case, the present invention can be applied. In contrast, the present invention can be applied even when a monochrome image using only black ink is recorded. In the present invention, when double-sided recording is performed, it is only necessary to perform processing so that a difference appears in the output value of multi-value data after color separation, and it is suitable for any number of colors after separation. Can be used.

  Furthermore, in recent years, many ink jet recording apparatuses have been provided in which an ink using a pigment as a color material as well as an ink using a dye as a color material is mounted. It is known that pigment ink has better color development on a recording medium than dye ink, but it takes time to fix. Therefore, it can be said that the present invention can further exert the effect in the ink jet recording system using the pigment ink.

  The data processing method of the embodiment described above is a process for achieving both reduction in standby time and character quality when performing double-sided recording. However, the user does not always seek to shorten the standby time when performing duplex recording. Therefore, in order to be able to cope with either case, the user can select whether priority is given to high-speed recording or high-quality recording, and the above embodiment is applied only when high-speed recording is selected. It may be.

  In the above embodiment, as shown in FIG. 2, the inkjet recording system including the main device and the recording device has been described as an example. In this case, the main device for supplying the recording data to the recording device may be a digital camera or an image scanner in addition to the computer. The computer may be a personal computer, an office computer, a workstation, or the like, or a PDA such as an electronic notebook or a handheld computer. Further, the configuration of the recording system may be separable into the recording device and the main device as in the above-described embodiment, but may be integrated so as not to be separable.

  Needless to say, software for realizing the above embodiments or printer driver program code supplied to a computer and operated by the program code stored in the computer is also included in the scope of the present invention.

  In this case, the program code itself realizes the novel function of the present invention, and the program code itself and means for supplying the program code to the computer by communication or storage medium are also included in the scope of the present invention.

  As a storage medium for supplying the program code, for example, a hard disk, an optical disk, a magneto-optical disk, a CD-R, a DVD, a magnetic tape, a nonvolatile memory card, a ROM, etc. are used in addition to a flexible disk and a CD-ROM. be able to.

  In addition, an OS or the like running on the computer performs part or all of the actual processing based on the instruction of the program code read by the computer, and the functions of the present embodiment are realized by the processing. .

  Further, the scope of the present invention includes a function in which the program code read from the storage medium is written in a memory provided in a function expansion board inserted in the computer or a function expansion unit connected to the computer. In this case, the CPU of the function expansion board or function expansion unit performs part or all of the actual processing based on the instruction of the program code, and the functions of this embodiment are realized by the processing.

It is a perspective view for demonstrating schematic structure of a serial type inkjet recording device. 1 is a block diagram for explaining an ink jet recording system including an ink jet recording apparatus applied to an embodiment of the present invention and a main apparatus connected to the recording apparatus and responsible for main image processing. It is a flowchart for demonstrating the flow of the image processing performed with an inkjet recording system. The output patterns for input levels 0 to 4 converted by the index expansion process are shown. It is a schematic diagram for demonstrating the attribute determination process of image data. It is a flowchart for demonstrating the determination process which the main apparatus main control part performs in order to set the method of an image processing. It is a flowchart for demonstrating each process of the color processing for both sides in a pixel unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conveyance roller 2 Pinch roller 4 Recording head 7 Carriage 12 Discharge roller 13 Spur 16 Reversing means 101 Recording apparatus main control part 102 Recording buffer 104 Feeding / discharging control part 105 Recording apparatus I / F part 106 Data buffer 107 System bus 108 Main apparatus Main control unit 109 Main unit I / F unit
DESCRIPTION OF SYMBOLS 110 Display part 111 Operation part 112 System bus 113 Carriage motor control part 301 Original image data 302 Character attribute part 303 Image attribute part 304 Graphic attribute part

Claims (13)

In an inkjet recording method of forming an image using a recording head that discharges one or more colors of ink,
Setting whether to record images on both sides of the recording medium;
Determining whether information other than character information is included in the image;
A first conversion step of converting multi-value luminance data of individual pixels constituting the image into multi-value density data corresponding to the ink color;
A second conversion step of converting the multi-value density data into binary data;
A step of ejecting ink from the recording head based on the binary data, and when double-sided recording is set in the setting step, it is determined that information other than character information is included in the determination step The multi-value density data after the first conversion process is lower than the multi-value density data after the first conversion process when it is determined that information other than character information is not included. An ink jet recording method, wherein:   In the first conversion step, the multi-value luminance data is converted into the multi-value density data corresponding to the ink color by using a conversion table prepared in advance, and information other than character information is obtained in the determination step. The conversion table applied when it is determined that the information is included is different from the conversion table applied when it is determined that information other than character information is not included. 2. The ink jet recording method according to 1. In an inkjet recording method of forming an image using a recording head that discharges one or more colors of ink,
Setting whether to record images on both sides of the recording medium;
A step of detecting an amount of information other than character information included in the image when double-sided recording is set by the setting step;
Comparing the amount of information other than the character information with a predetermined threshold;
A first conversion step of converting multi-value luminance data of individual pixels constituting the image into multi-value density data corresponding to the ink color;
A second conversion step of converting the multi-value density data into binary data;
A step of ejecting ink from the recording head based on the binary data, and the first conversion step when it is determined in the comparison step that the amount of information other than the character information is larger than the threshold value. The subsequent multi-value density data is at a lower level than the multi-value density data when the amount of information other than the character information is determined to be equal to or less than the threshold value.   The first conversion step converts the multi-value luminance data into the multi-value density data according to ink color using a conversion table prepared in advance, and information other than the character information in the comparison step. The conversion table applied when it is determined that the amount of information is larger than the threshold is different from the conversion table applied when the amount of information other than the character information is determined to be equal to or less than the threshold. The inkjet recording method according to claim 3. In an inkjet recording method of forming an image using a recording head that discharges one or more colors of ink,
Setting whether to record images on both sides of the recording medium;
A step of determining whether or not each pixel constituting the image is a pixel constituting a character when double-sided recording is set by the setting step;
A first conversion step of converting multi-value luminance data of the individual pixels into multi-value density data corresponding to ink colors;
A second conversion step of converting the multi-value density data into binary data;
And the step of ejecting ink from the recording head based on the binary data, and the multi-value density data after the first conversion step of pixels determined not to constitute character information in the determination step Is a low level compared to the multi-value density data when it is determined that the pixel constitutes character information.   In the first conversion step, the multi-value luminance data is converted into the multi-value density data corresponding to the ink color by using a conversion table prepared in advance, and pixels constituting character information in the determination step 6. The inkjet according to claim 5, wherein the conversion table applied to the pixels determined to be different from the conversion table applied to the pixels determined not to constitute the character information are different from each other. Recording method.   7. The ink jet recording method according to claim 1, wherein the ink colors are four colors of cyan, magenta, yellow and black. In an inkjet recording system for forming an image using a recording head that discharges one or more colors of ink,
Means for setting whether to record an image on both sides of the recording medium;
Means for determining whether information other than character information is included in the image;
First conversion means for converting multivalued luminance data of individual pixels constituting the image into multivalued density data corresponding to the ink color;
Second conversion means for converting the multi-value density data into binary data;
And means for ejecting ink from the recording head based on the binary data. When double-sided recording is set in the setting step, it is determined that information other than character information is included in the determination step. The multi-value density data after the first conversion process is lower than the multi-value density data after the first conversion process when it is determined that information other than character information is not included. An inkjet recording system characterized by the above. In an inkjet system that forms an image using a recording head that discharges one or more inks,
Means for setting whether to record an image on both sides of the recording medium;
Means for detecting an amount of information other than character information included in the image when double-sided recording is set by the setting step;
Means for comparing an amount of information other than the character information with a predetermined threshold;
First conversion means for converting multivalued luminance data of individual pixels constituting the image into multivalued density data corresponding to the ink color;
Second conversion means for converting the multi-value density data into binary data;
Means for discharging ink from the recording head based on the binary data, and the first conversion step when it is determined in the comparison step that the amount of information other than the character information is larger than the threshold value. The subsequent multi-value density data is at a lower level than the multi-value density data when the amount of information other than the character information is determined to be equal to or less than the threshold value. In an inkjet recording system for forming an image using a recording head that discharges one or more colors of ink,
Means for setting whether to record an image on both sides of the recording medium;
Means for determining whether or not each pixel constituting the image is a pixel constituting a character when double-sided recording is set by the setting step;
First conversion means for converting multi-value luminance data of the individual pixels into multi-value density data corresponding to ink color;
Second conversion means for converting the multi-value density data into binary data;
Means for ejecting ink from the recording head based on the binary data, and the multi-value density data after the first conversion step of a pixel determined not to constitute character information in the determination step Is a low level compared to the multi-value density data when it is determined that the pixel constitutes character information.   11. An ink jet recording apparatus that is applicable to the ink jet recording system according to claim 8 and that performs recording using a recording head that ejects one or more colors of ink based on binary data.   A control program for executing the ink jet recording method according to claim 1. A storage medium storing a control program for executing the ink jet recording method according to claim 1.

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