JP4696696B2 - Inkjet recording system and image processing program - Google Patents

Description

  The present invention relates to a photocurable ink jet recording system and an image processing program used therefor.

  In general, an ink jet recording apparatus (hereinafter, referred to as “ink jet recording apparatus”) is known as an ink jet recording apparatus that can flexibly meet the demand for a small variety of products. An ink jet recording apparatus records an image on a recording medium by ejecting ink from a nozzle provided on the surface of the recording head facing the recording medium, and landing and fixing on the recording medium. Conventional gravure printing Unlike the image recording means based on the system or flexographic printing system, it does not require a plate making process, and therefore can easily and quickly respond to a small amount of demand. In addition, there is an advantage that color image recording can be easily performed by using multi-color ink with less noise.

  Further, in recent years, an ink jet recording apparatus using a photocurable ink is known as an ink jet recording apparatus compatible with various recording media (see, for example, Patent Document 1). In such an ink jet recording apparatus, photocurable ink containing a photoinitiator having a predetermined sensitivity to light such as ultraviolet rays is ejected, and light is applied to the ink landed on the recording medium. The ink is cured and fixed on the recording medium. In such an ink jet recording apparatus, ink is instantly cured by irradiating light after ink landing, so that there is little ink permeation or bleeding into the recording medium, and there is no ink receiving layer as well as plain paper. It is possible to record an image on a recording medium such as plastic or metal that has no absorbability.

As an ink jet recording method, a multi-pass recording method is known (see, for example, Patent Document 2). This multi-pass printing method is a method of printing an image by dividing a large number of nozzles in a printing head into a plurality of nozzle groups and performing a plurality of scans on the same printing area using different nozzle groups. According to this method, it is possible to reduce streaks and unevenness caused by variations in the ejection amount for each nozzle of the recording head, landing deviation, and paper feed error.
JP 2001-310454 A JP-A-5-31919

  If there is variation in the position or ejection direction of each nozzle of the recording head, the landing position of the ink on the recording medium will shift, and a narrow part or a wide part will occur in the interval from the landing position of the adjacent ink. Or

  When recording is performed on a recording medium that does not absorb ink using a photocurable ink jet recording apparatus, the landed ink is not absorbed by the recording medium and rises. In this case, if a deviation occurs in the landing position, the inks are connected by surface tension in a portion where the distance from the landing position of the adjacent ink is narrow, and the ink is isolated in a wide portion. In this state, when the recording head is scanned relative to the recording medium and recorded on the recording medium, streaky unevenness occurs in the scanning direction on the recording medium.

  When recording is performed on a recording medium having ink absorptivity using a photocurable inkjet recording apparatus, the ink is cured by light irradiation before the ink sufficiently penetrates into the recording medium. The portion where the ink is cured is in a state where the ink cannot be absorbed any more. In the case of the multi-pass recording method, recording is performed on a recording medium in which the ink has already been cured in the second and subsequent scans (passes). The pixels to be recorded in each pass are different, but the dot diameter of the ink that normally lands is set to be large so as to cover all the pixels, so even the next pixel that is not actually recorded yet Overhangs are recorded. In the last pass, the ink has already landed and hardened, and the probability of ink being ejected is high. In this case, the ink that landed in the last pass rises without being absorbed by the recording medium. Therefore, when recording on a recording medium having ink absorptivity, streaky unevenness occurs as in the case of recording on a recording medium having no ink absorption.

  When performing bidirectional recording by irradiating light while reciprocating the recording head in a direction orthogonal to the recording medium conveyance direction, the ink ejected from the recording head in the forward direction and the backward direction is usually used. Since the time until light irradiation is different, the dot diameter of the landed ink and the connection between the dots differ, and the glossiness of the recorded image differs between forward recording and backward recording. End up.

  The above phenomenon is particularly apparent when black ink is recorded at a high recording rate.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to suppress the occurrence of streaky unevenness in the scanning direction in a photocurable ink jet recording system. The object is also preferably to suppress gloss unevenness in both directions.

According to the first aspect of the present invention, there is provided image processing means for performing image processing of CMYK color conversion processing on input image data, and for each of C, M, Y, and K colors based on the image processed image data. In an ink jet recording system comprising a photocurable ink jet recording means for recording on a recording medium using a different recording head ,
The image processing means replaces the highest gradation value of the K data of some pixels other than the edge portion among the pixels indicating the highest gradation value of the K data after the CMYK color conversion processing with the lowest gradation value. A first replacement process;
Second replacement for replacing each gradation value of C, M, and Y data of some pixels other than the edge portion among the pixels indicating the highest gradation value of the K data after the CMYK color conversion processing with the highest gradation value. And K data replacement processing means for performing the processing.

According to a second aspect of the present invention, in the ink jet recording system according to the first aspect, the first replacement processing of the K data replacement processing means is performed by using 10 to 50 pixels out of pixels indicating the highest gradation value of the K data. % Of the gradation values of the pixels are replaced with the lowest gradation value, and the second replacement processing is performed by changing the C, M, and Y data of 10 to 70% of the pixels indicating the highest gradation value of the K data. Each gradation value is replaced with a maximum gradation value.

According to a third aspect of the present invention, in the ink jet recording system according to the second aspect, the first replacement processing of the K data replacement processing means is performed in 40-50 of the pixels indicating the highest gradation value of the K data. % Of the gradation values of the pixels are replaced with the lowest gradation value, and the second replacement process performs the conversion of the C, M, and Y data for 10 to 20% of the pixels indicating the highest gradation value of the K data. Each gradation value is replaced with a maximum gradation value.

According to a fourth aspect of the present invention, in the ink jet recording system according to any one of the first to third aspects, the curable ink jet recording means is a multi-pass recording method, and the K data replacement processing means is In the multi-pass recording, at least the K data related to the final pass is replaced.

The invention according to claim 5 is an image processing program for performing image processing when transferring input image data to a photo-curable ink jet recording means using different recording heads for each of C, M, Y, and K colors. A CMYK color conversion step for performing CMYK color conversion processing on the input image data to the computer, and a part other than the edge portion of the pixels indicating the highest gradation value of the K data after the CMYK color conversion processing A first replacement processing step of replacing the highest gradation value of the K data of the pixel with the lowest gradation value, and one other than the edge portion of the pixels indicating the highest gradation value of the K data after the CMYK color conversion processing. A K data replacement processing step having a second replacement processing step of replacing each gradation value of the C, M, Y data of the pixels of the portion with the highest gradation value ;
It is characterized by executing .

According to the first, second, and fifth aspects of the present invention, regular unevenness in the main scanning direction caused by dot connection / isolation in the black solid portion reduces the K recording rate and thins out the dots. It becomes divided and becomes inconspicuous. Larger hardening can be obtained by thinning out at random. Furthermore, since K data replacement is not performed for the edge portion, CMY colors are not added to the edge portion, and the problem of color misalignment of the edge portion does not occur. Degradation of character quality can be suppressed.

  Further, the C, M, and Y recording heads are different from the K recording head, and even if ink is landed on the same pixel on the recording medium, there are variations in nozzle positions and ejection directions depending on the heads. Therefore, it is slightly shifted from the landing position of K. For this reason, by adding the C, M, and Y inks that are out of the landing position of the K ink to the black solid portion, regular unevenness in the main scanning direction due to the K ink becomes inconspicuous. A larger effect can be obtained by adding randomly.

  According to the third aspect of the present invention, since the absolute amount of dots to be recorded is reduced, there is not much connection of dots in the forward direction and the backward direction in bidirectional recording, and gloss unevenness becomes inconspicuous.

According to the fourth aspect of the present invention, the recording of the last pass greatly contributes to the influence on the unevenness in the main scanning direction and the unevenness of gloss, and does not contribute much until the pass before the final pass. When recording, it is possible to obtain a high-density black solid image with a small amount of ink by recording only with black ink until the pass before the final pass.

(1) Configuration of Inkjet Recording System FIG. 1 is a block diagram showing the configuration of an inkjet recording system as one embodiment of the present invention. The image processing apparatus 100 and the inkjet recording apparatus 200 are connected via a communication line 400 such as a LAN.

  The image processing apparatus 100 includes a personal computer 110, a display device 130 such as an LCD display or a CRT display connected to the personal computer 110 via a video interface (VI / F) 111, and a peripheral device interface (P -I / F) 112, and an input device 140 such as a keyboard and a scanner connected to each other.

  The personal computer 110 includes the following units connected to each other by a bus 114 with a CPU 113 that executes various arithmetic processes for controlling operations related to image processing according to a program.

  The ROM 115 stores programs and data necessary for executing various arithmetic processes by the CPU 113 in advance, and the RAM 116 temporarily reads various programs and data necessary for executing various arithmetic processes by the CPU 113. It is memory.

  A disk controller (DDC) 117 controls data exchange with a hard disk drive (HDD) 118 and a CD-ROM drive 119. The HDD 118 stores various programs loaded into the RAM 116 and executed, various programs provided in the form of device drivers, and the like. A program necessary for image processing in this embodiment is loaded from the CD-ROM to the HDD 118 using the CD-ROM drive 119.

  The network interface card (NIC) 120 is an interface for connecting to a network via the communication line 400. By connecting to a specific server 300 via the NIC 120, a program necessary for image processing can be downloaded to the HDD 118.

  FIG. 2 is a block diagram illustrating a software configuration of the image processing apparatus 100. In the personal computer 110, an application program 150 operates under a predetermined operating system. The application program 150 acquires and edits an image via an input device 140 such as a scanner or a keyboard. The operating system incorporates a video driver 151 and a printer driver 152, and the image data output from the application program 150 is displayed on the display device 130 via these drivers and output to the inkjet recording device 200. The

  When the application program 150 issues a print command, the printer driver 152 of the personal computer 110 receives the image data from the application program 150 and converts it into a signal that can be printed by the inkjet recording apparatus 200. In the example illustrated in FIG. 2, the printer driver 152 includes a rasterization processing unit 153 that converts image data handled by the application program 150 into RGB gradation data in units of pixels, and the RGB gradation data is converted into the inkjet recording apparatus 200. Color conversion processing unit 154 for converting to CMYK gradation data corresponding to the color development characteristics of the image, K data replacement processing unit 155 for replacing a part of K data in the CMYK gradation data with CMY data, CMYK gradation data after replacement Is converted to the number of gradations that can be printed by the inkjet recording apparatus 200, and an interlaced data generation section 157 that rearranges the multivalued image data in the order to be transferred to the inkjet recording apparatus 200. ing.

  FIG. 3 is a configuration diagram illustrating an outline of the ink jet recording apparatus 200. The ink jet recording apparatus 200 is provided with a platen 201 that is formed on a flat plate and supports the recording medium P. A bar-shaped guide rail 202 extending in the longitudinal direction of the platen 201 is provided above the platen 201. A carriage 203 is supported on the guide rail 202, and the carriage 203 can reciprocate in the main scanning directions A and B along the guide rail 202. The inkjet recording apparatus 200 is provided with a transport roller 204 that transports the recording medium P in the transport direction X orthogonal to the main scanning directions A and B.

  On the carriage 203, four recording heads 205 corresponding to black (K), cyan (C), magenta (M), and yellow (Y) are mounted. On the surface of each recording head 205 facing the recording medium, a plurality of ink discharge ports (not shown) formed in a row are provided orthogonal to the main scanning directions A and B, and are located with respect to the recording medium P. Ink is ejected. The ink used is not limited to this, and for example, light cyan (LC), light magenta (LM), or the like can be used.

  Ultraviolet light sources 206 are provided at both ends of the carriage 203 across the four recording heads 205. The ultraviolet light source 206 irradiates ultraviolet rays as light for curing and fixing the ink ejected and landed on the recording medium P. As this ultraviolet light source, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, a semiconductor laser, a cold cathode tube, an excimer lamp, or an LED can be applied.

  The ink used in the present embodiment is a photocurable ink having a property of being cured when irradiated with ultraviolet rays as light, and has at least a polymerizable compound (including a known polymerizable compound) as a main component. And a photoinitiator and a coloring material. The photocurable ink is roughly classified into a radical polymerization ink containing a radical polymerizable compound as a polymerizable compound and a cationic polymerization ink containing a cationic polymerizable compound. Both inks are included in this embodiment. Each can be applied as the ink used. Further, a hybrid ink in which radical polymerization ink and cation polymerization ink are combined may be applied as the ink used in this embodiment. However, since cationic polymerization inks that have little or no inhibitory action on polymerization reaction due to oxygen are superior in functionality and versatility, it is particularly preferable to use cationic polymerization inks. The cationic polymerization ink is a mixture containing at least a cationic polymerizable compound such as an oxetane compound, an epoxy compound, and a vinyl ether compound, a photocationic initiator, and a coloring material.

  Further, as the recording medium P, recording paper P made of various materials such as various papers such as plain paper, recycled paper, glossy paper, various fabrics, various non-woven fabrics, resin, metal, and glass can be applied. In addition, as the form of the recording medium P, various forms such as a roll form, a cut sheet form, and a plate form are applicable.

  FIG. 4 is a block diagram illustrating a control configuration of the inkjet recording apparatus 200. The ink jet recording apparatus 200 includes the following units connected to each other by a bus 207, with a CPU 208 executing various arithmetic processes for controlling operations related to the ink jet recording apparatus 200 according to a program.

  The ROM 209 stores in advance programs and data necessary for the CPU 208 to execute various arithmetic processes, and the RAM 210 temporarily reads various programs and data necessary for the CPU 208 to execute various arithmetic processes. It is memory.

  The carriage drive circuit 211 is a circuit for driving a motor (not shown) for moving the carriage 203, and is controlled by the CPU 208 to reciprocate the carriage 203 in the main scanning directions A and B. The recording medium conveyance drive circuit 212 is a circuit for driving a motor (not shown) for conveying the recording medium P in the conveyance direction X. The recording medium P is moved in the conveyance direction X in accordance with the operation of the carriage 203. The CPU 208 controls the intermittent conveyance. The head drive circuit 213 is a circuit for driving an ink discharge drive element (not shown) such as a piezoelectric element for discharging ink from the recording head 205 so that ink is discharged based on image data. Controlled by the CPU 208. The ultraviolet light source driving circuit 214 is a circuit for driving the ultraviolet light source 206, and is controlled by the CPU 208 to cure and fix the ink ejected and landed on the recording medium P.

  A network interface card (NIC) 215 is an interface for connecting to a network via the communication line 400, and print image data is input via the NIC 215.

  Next, an image recording operation of the inkjet recording apparatus 200 will be described. The CPU 208 controls the carriage driving circuit 211 and the recording medium conveyance driving circuit 212 to reciprocate the carriage 203 in the main scanning directions A and B at a constant speed, and at the time of switching the moving direction of the carriage 203 P is intermittently conveyed by a predetermined amount in the conveyance direction X. Further, the CPU 208 controls the ultraviolet light source driving circuit 214 to turn on the ultraviolet light source 206 at the time of image recording, to irradiate the ink ejected in each scan and landed on the recording medium P with ultraviolet rays. Is cured and fixed.

  In addition, the inkjet recording apparatus 200 employs the multipass recording method described above. In this embodiment, image recording is performed by six scans.

  FIG. 5 is a diagram conceptually showing the image recording operation in the ink jet recording apparatus 200. In FIG. 5, in order to focus on a predetermined recording area on the recording medium P, for convenience, the recording medium P is fixed and the recording head 205 is relatively moved. Although eleven heads are shown in the figure, these are all the same one recording head 205 and merely show the position of the recording head 205 relative to the recording medium P in each scan. The positional deviation in the sub-scanning direction between adjacent heads in the figure corresponds to the feed amount of the recording medium P that is intermittently conveyed for each scan.

  Focusing on one band on the recording medium P between the broken lines in the figure, image recording is performed in six scans in this one band, and the CPU 208 controls the head drive circuit 213 to perform six times. Ink is ejected from the recording head 205 so that the recording of all the pixels in one band is completed by this scanning.

  For example, in the band A in the figure, the first scanning is performed along the main scanning direction A, the first scanning image recording is performed by the ink ejected from the nozzle group on one end side of the recording head 205, and the ultraviolet rays are used. Curing and fixing of the ink recorded by the ultraviolet irradiation from the light source 206 is performed. Next, a second scan is performed along the main scanning direction B, and image recording for the second scan is performed by ink ejected from the nozzle group inside the nozzle group on the one end side of the recording head 205, and ultraviolet rays are also used. Curing and fixing of the ink recorded by the ultraviolet irradiation from the light source 206 is performed. Similarly, the third scan, the fourth scan, and the fifth scan are sequentially performed, and finally, the sixth scan is performed along the main scanning direction B, and discharged from the nozzle group on the other end side of the recording head 205. The image recording of the sixth scan is performed with the ink, and the ink recorded by the ultraviolet irradiation from the ultraviolet light source 206 is cured and fixed. In this way, recording and fixing are completed for all the pixels in band A.

  For band B, image recording and fixing are performed by six scans from the second scan to the seventh scan, and for band C, image recording and fixing are performed by six scans from the third scan to the eighth scan. Is called.

  FIG. 6A is a dot matrix showing how many times the ink is ejected to each pixel when band A is printed by six scans. In the figure, the horizontal direction is the main scanning direction, and each square represents one pixel. The numbers from 1 to 6 indicate in what scan the ink is ejected for each pixel. In the first scan, ink is ejected to the first pixel in the drawing, and in the second scan, ink is ejected to the second pixel. Hereinafter, ink is ejected to the third pixel in the third scan, the fourth pixel in the fourth scan, the fifth pixel in the fifth scan, and finally the sixth pixel in the sixth scan, and all the pixels are recorded. Is done. Similarly, FIG. 6B shows a case where band B is recorded. Each number of pixels is recorded in each scan from the second scan to the seventh scan.

(2) Recording Data Generation Control The recording data generation control process in this embodiment will be described. The flow of the recording data generation control routine is shown in FIG. This is a process executed by the CPU 113 of the personal computer 110.

  When this process is started, the CPU 113 inputs image data (step S100). This image data is data transferred from the application program 150 shown in FIG.

  Next, the CPU 113 sets pixels corresponding to the recording resolution of the ink jet recording apparatus 200, and sets the input image data in 256 levels from 0 to 255 for each color of R, G, and B for each pixel. A rasterization process is performed to convert the data into data having the gradation values (step S110).

  Next, the CPU 113 performs color conversion processing for converting image data composed of R, G, and B gradation values into gradation values of C, M, Y, and K colors that are used in the inkjet recording apparatus 200 (steps). S120). This process is performed using a color conversion table (not shown) that stores C, M, Y, and K for expressing colors composed of combinations of R, G, and B by the inkjet recording apparatus 200.

  Next, the CPU 113 performs K data replacement processing for replacing part of the K data in the image data composed of C, M, Y, and K gradation values with CMY data (step S130). The K data replacement process is a main part of the present invention, and will be described later in detail with reference to FIG.

  Next, the CPU 113 performs multi-value processing on the C, M, Y, and K image data on which the K data replacement processing has been performed (step S140). Multi-leveling means that the gradation value of original image data (256 gradations in the present embodiment) is converted into gradation values that can be expressed for each pixel by the inkjet recording apparatus 200. In the present embodiment, multi-value conversion to two gradations “with dot” and “without dot” is performed, but multi-value conversion to more gradations may be performed.

  Next, the CPU 113 generates interlace data (step S150). The rasterized data is rearranged in the order of transfer to the recording head 205 of the inkjet recording apparatus 200. In this embodiment, as described above, it is a 6-pass multi-pass recording method. First, the first data in FIG. 6A is picked up, and then the second, third, fourth, fifth, The sixth data is picked up in order, and the data is rearranged in the order of transfer to the recording head 205.

  When data that can be recorded by the inkjet recording apparatus 200 is generated in this way, the CPU 113 outputs the data and transfers it to the inkjet recording apparatus 200 (step S160).

(3) K Data Replacement Process The contents of the K data replacement process in this embodiment will be described with reference to FIG.

  First, in the K data replacement process, the CPU 113 inputs image data. (Step S131). The image data input here is data that has been subjected to color conversion processing (step S120 in FIG. 7) and has 256 gradations for each color of C, M, Y, and K. This data is the original data.

  Next, the CPU 113 creates data obtained by extracting only the pixel of the gradation value 255, which is the highest gradation, from the K original data, and stores it as K255 data (step S132).

  Next, the CPU 113 shifts the address of the K255 data upward by one raster, and stores this as the shift data 1 (step S133).

  Next, the CPU 113 shifts the address of the K255 data downward by one raster, and stores this as the shift data 2 (step S134).

  Next, the CPU 113 shifts the K255 data, the shift data 1 and the shift data 2 to the left and stores them as the shift data 3, 4 and 5 (step S135).

  Next, the CPU 113 shifts the K255 data, the shift data 1 and the shift data 2 to the right, and stores them as the shift data 6, 7 and 8 (step S136).

  Next, the CPU 113 takes AND data of the K255 data and the shift data 1 to 8, and obtains K255 data other than the edge portion, that is, internal data (step S137).

  Next, the CPU 113 replaces K255 data pixels other than the edge portion with a gradation value of 0 (K0 data) at a predetermined ratio. This is also reflected in the K original data (step S138). For example, 40% of the number of pixels of K255 data other than the edge portion is randomly replaced with K0 data. That is, the recording rate of K255 data is reduced to 60%.

  Next, the CPU 113 randomly replaces each C, M, Y original data pixel corresponding to the K255 data pixel other than the edge portion with a gradation value 255 (C255, M255, Y255 data) at a predetermined ratio (step S139). ). For example, 20% of the number of C, M, and Y original data pixels corresponding to K255 data pixels other than the edge portion is randomly replaced with C255, M255, and Y255 data. The recording rate of C255, M255, and Y255 data is 20%. The pixel to be replaced need not be common to each of C, M, and Y, and may be independent for each color. Further, the recording rates of C, M, and Y are not necessarily the same if there is no problem with the hue.

  As described above, regular irregularities in the main scanning direction caused by dot connection and isolation in the black solid portion are divided in the main scanning direction and become inconspicuous by reducing the K recording rate and thinning out the dots. Greater effects can be obtained by random thinning.

  Further, the C, M, and Y recording heads are different from the K recording head, and even if ink is landed on the same pixel on the recording medium, there are variations in nozzle positions and ejection directions depending on the heads. Therefore, it is slightly shifted from the landing position of K. For this reason, by adding the C, M, and Y inks that are out of the landing position of the K ink to the black solid portion, regular unevenness in the main scanning direction due to the K ink becomes inconspicuous. A larger effect can be obtained by adding randomly.

  The preferable range of the recording rate of K255 data is preferably 50 to 90% (50 to 10% in terms of substitution ratio). If it exceeds 90%, regular unevenness in the main scanning direction cannot be sufficiently eliminated. In addition, if it is less than 50%, the density cannot be obtained, and in order to secure the density, CMY must be increased instead. However, the total ink amount increases, the hue does not match, or the color at the edge portion is increased. Misalignment may occur.

  The preferable range of the recording rate of the C255, M255, and Y255 data is preferably 10 to 70%. If it exceeds 70%, the total ink amount will increase, the hue will not match, or color deviation will occur at the edge. On the other hand, if it is less than 10%, black solid density cannot be obtained, and regular unevenness in the main scanning direction cannot be sufficiently eliminated.

  If the recording rate of K255 data is 50-60% (50-40% in terms of substitution ratio) and the recording rate of C255, M255, Y255 data is 10-20%, respectively, the absolute amount of dots to be recorded Therefore, the dot connection is not so much in both the forward direction and the backward direction in bidirectional recording, and gloss unevenness becomes inconspicuous.

  In this embodiment, since K data replacement is not performed for the edge portion, CMY color is not added to the edge portion, and the problem of color misregistration of the edge portion does not occur. Degradation of character quality can be suppressed.

  The replacement of the K255 data may be performed at least in the final pass when applied to mast pass recording. Regarding the influence on unevenness in the main scanning direction and uneven glossiness, the recording of the last pass greatly contributes, and does not contribute much until the pass before the final pass. When printing is performed only with black ink until the pass, a high density black solid image can be obtained with a small amount of ink. Of course, it may be performed for all paths. In this case, there is an advantage that the processing is simplified.

  In this embodiment, the K data replacement process is performed based on the CMYK data before the multi-value conversion. However, the K data replacement process may be performed based on the data after the multi-value conversion of the CMYK data. For example, in the case of binary values, the number of K1 data pixels in a predetermined ratio is replaced with K0 data, and pixels in a predetermined ratio of C, M, and Y pixels corresponding to K1 data pixels are replaced with C1, M1, and Y1 data. do it.

  In the present embodiment, the recording head is reciprocated in the main scanning direction, and the recording medium is intermittently conveyed in the direction orthogonal to the main scanning direction, and ink is ejected from each recording head to form an image. Although the method has been described, it is also possible to suppress regular unevenness in the conveyance direction of the recording medium, which is the main scanning direction of the line recording method, by applying to the line recording method.

  In this embodiment, the image processing including the K data replacement processing is performed by the personal computer 110, but may be performed by the ink jet recording apparatus 200. Furthermore, the image processing may be shared between the personal computer 100 and the ink jet recording apparatus 200. For example, after the multi-value processing, the image processing may be performed on the ink jet recording apparatus 200 side.

  In this embodiment, the image processing including the K data replacement processing is provided with the function of the printer driver, but may be provided with image processing software different from the printer driver.

  In this embodiment, image recording is performed using ink that is cured by irradiation with ultraviolet rays. However, the ink is not necessarily limited to this, and for example, ultraviolet rays, electron beams, X-rays, and visible rays. The ink may be cured by irradiating light other than ultraviolet rays such as electromagnetic waves such as infrared rays. In this case, a polymerizable compound that is polymerized and cured with light other than ultraviolet light and a photoinitiator that initiates a polymerization reaction between the polymerizable compounds with light other than ultraviolet light are applied to the ink. In the case of using a photocurable ink that is cured by light other than ultraviolet light, a light source that emits the light is applied instead of the ultraviolet light source.

1 is a block diagram illustrating a configuration of an inkjet recording system according to an embodiment of the present invention. It is a block diagram which shows the software structure of the image processing apparatus which concerns on embodiment of this invention. 1 is a configuration diagram illustrating an outline of an ink jet recording apparatus according to an embodiment of the present invention. It is a block diagram which shows the control structure of the inkjet recording device which concerns on embodiment of this invention. It is a conceptual diagram of the image recording operation | movement in the inkjet recording device which concerns on embodiment of this invention. FIG. 6A is a dot matrix showing how many inks are ejected to each pixel when band A is recorded by six scans. FIG. 6B is a diagram showing a dot matrix when band B is recorded. It is a flowchart which shows the recording data generation control routine which concerns on embodiment of this invention. It is a flowchart which shows the K data replacement processing routine which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image processing apparatus 110 Personal computer 152 Printer driver 153 Rasterization process part 154 Color conversion process part 155 K data replacement process part 156 Multi-value conversion process part 157 Interlace data generation part 200 Inkjet recording apparatus 205 Recording head 206 Ultraviolet light source

Claims (5)

Recording medium using image processing means for performing image processing of CMYK color conversion processing on input image data, and different recording heads for C, M, Y, and K colors based on the image processed image data In an ink jet recording system comprising: a photocurable ink jet recording means for recording on
The image processing means replaces the highest gradation value of the K data of some pixels other than the edge portion among the pixels indicating the highest gradation value of the K data after the CMYK color conversion processing with the lowest gradation value. A first replacement process;
Second replacement for replacing each gradation value of C, M, and Y data of some pixels other than the edge portion among the pixels indicating the highest gradation value of the K data after the CMYK color conversion processing with the highest gradation value. And an K data replacement processing means for performing the processing. The first replacement process of the K data replacement processing unit replaces the gradation value of 10 to 50% of the pixels indicating the highest gradation value of the K data with the lowest gradation value, and the second replacement process . 2. The replacing process replaces each gradation value of C, M, and Y data with a maximum gradation value for 10 to 70% of the pixels indicating the maximum gradation value of the K data. The inkjet recording system described in 1. The first replacement process of the K data replacement processing unit replaces the gradation value of 40 to 50% of the pixels indicating the highest gradation value of the K data with the lowest gradation value, and the second replacement process . 3. The replacing process replaces each gradation value of C, M, and Y data with a maximum gradation value for 10 to 20% of the pixels indicating the maximum gradation value of the K data. The inkjet recording system described in 1. The photo-curable ink jet recording means is a multi-pass recording method, and the K data
The replacement processing means applies to at least the K data related to the final pass in multi-pass recording.
The inkjet recording according to any one of claims 1 to 3, wherein the replacement is carried out.
system. In an image processing program for performing image processing when transferring input image data to a photo-curable inkjet recording means using different recording heads for each of C, M, Y, and K colors,
On the computer,
A CMYK color conversion step of performing CMYK color conversion processing on the input image data;
A first replacement processing step of replacing the highest gradation value of the K data of a part of the pixels other than the edge portion among the pixels indicating the highest gradation value of the K data after the CMYK color conversion processing with the lowest gradation value ; The second gradation value is used to replace the gradation values of the C, M, and Y data of some of the pixels other than the edge portion among the pixels indicating the highest gradation value of the K data after the CMYK color conversion process with the highest gradation value . A K data replacement processing step having a replacement processing step;
An image processing program for executing

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