JP2019162814A - Color prediction method of inkjet method and inkjet printing method - Google Patents

Abstract

To appropriately predict color after color development processing in the case of performing printing with an inkjet method by using ink that develops color by the color development processing.SOLUTION: A color prediction method of an inkjet method for predicting color to be printed by the inkjet method includes: an ink discharge step (S104) for discharging ink of a plurality of colors different from one another to a medium to be discharged by an inkjet head on the basis of image data showing a color image by using ink that develops color by color development processing; a color measurement step (S106) for measuring ink color before performing color development processing; and a color prediction step (S108) for predicting color after performing the color development processing to the ink, and predicts the color after performing the color development processing on the basis of color information showing color designated to each position of an image in image data and a measurement result of the color before the color development processing measured by the color measurement step in the color prediction step.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a color prediction method for an inkjet method and an inkjet printing method.

  Conventionally, ink jet printers that perform printing by an ink jet method have been widely used. Further, as ink for an ink jet printer, an ink that develops color by a coloring process, such as sublimation transfer ink, may be used. In this case, for example, after the ink is ejected onto a transfer medium such as transfer paper, a coloring process for coloring the ink is performed at the time of transfer or after the transfer. Conventionally, a configuration for performing color correction is known for a printing apparatus using a sublimation transfer material (see, for example, Patent Document 1).

JP 2002-262116 A

  When using an ink that requires color development, the color obtained after color development may not be a desired color. In such a case, for example, as in the method described in Patent Document 1, it is conceivable to actually read and correct the color after the color development processing with a scanner or the like. However, when printing is performed by the inkjet method, it may be desirable to predict the color after color development before performing the color development process. More specifically, for example, in the case where printing is performed by an ink jet method using ink that develops color by color development processing, usually, after ejecting ink (ink droplets) from an ink jet head to a medium (transfer medium or the like), in another step Color the ink. In this case, in consideration of reducing the man-hours required for predicting the color, it may be desirable to predict the color after color development without actually developing the ink. Therefore, conventionally, regarding the case where printing is performed by an ink jet method using ink that develops color by color development processing, it has been desired to perform color prediction by a more appropriate method. Therefore, an object of the present invention is to provide an ink jet color prediction method and an ink jet printing method that can solve the above-described problems.

  The inventor of the present application has earnestly studied how to predict colors when printing is performed by an ink jet method using ink that develops color by color development. First, it was considered to predict the color after the coloring process based on the color expressed by the ink before coloring on the medium. More specifically, the ink that develops color by the color development process is usually not colorless at all, but exhibits a certain color even before the color development process. In this case, a certain amount of color is expressed in the image on the medium even after the image is drawn by ejecting ink onto the medium and before the color forming process is performed. Therefore, in this case, if the relationship between the color before color development processing and the color after color development processing is acquired in advance, the color after color development processing is based on the color expressed by the ink before color development on the medium. It seems to be able to predict colors.

  However, when the inventor of the present application has actually confirmed through various experiments and the like, it has been found that it is difficult for such a method to appropriately predict the color after the coloring process. More specifically, for example, the color range (gamut) that can be expressed by the ink before color development is usually narrower than the color range that can be expressed by the ink after color processing. In this case, even if the color expressed by the ink before color development looks close, there may be a color having a large color difference after color development processing. As a result, when the color after color processing is predicted based on the color expressed by the ink before color development, there is a large difference between the color of the prediction result and the color actually expressed after color processing. Is likely to occur. Moreover, such a difference becomes large especially in the case of an achromatic color or a color close to an achromatic color.

  On the other hand, the inventor of the present application, as a result of further earnest research, as input information for performing prediction, in addition to the color before color development processing, the color of each position on the medium is the color of the ink. We considered using information that indicates whether it is expressed in combination. Further, as such information, it has been considered to use color information indicating a color designated for each position of an image in image data indicating a color image. Moreover, it was confirmed that color prediction can be performed more appropriately by such a method by actually conducting experiments and the like.

  Further, through further earnest research, the inventors have found characteristics necessary for obtaining such an effect and have reached the present invention. In order to solve the above problems, the present invention is an ink jet color prediction method for predicting a color to be printed by an ink jet method, and ejects ink onto a medium to be ejected, which is a medium on which ink is ejected. The ink corresponding to the image data is ejected to the ejection target medium by an ink jet head based on the image data indicating the color image using ink that is colored by the color development process. A step of measuring the color of an image drawn on the medium to be ejected in the ink ejection stage, and a step of measuring an ink color before the color forming process is performed. And a color prediction stage for predicting the color after the color development process is performed on the ink, and in the color prediction stage, the image data The color after the color development process is predicted based on the color information indicating the color designated for the position and the measurement result of the color before the color development process measured in the color measurement stage. And

  When configured in this manner, for example, when printing is performed by an ink jet method using ink that develops color by color development processing, it is possible to appropriately predict the color after color development processing before actually performing color development processing. . In this case, in addition to the measurement result of the color before the color development process measured at the color measurement stage, the color information specified in the image data is further used, so that high accuracy prediction can be performed more appropriately. . Therefore, with this configuration, for example, when printing is performed by an ink jet method using ink that is colored by color development, the color after the color development can be appropriately predicted.

  In addition, it is conceivable to use, for example, sublimation transfer ink as the ink that develops color by the color development process in the ink ejection stage. In this case, as the medium to be ejected, for example, a transfer medium that is a medium used when transferring an image to another medium is used. Then, an image is drawn on the transfer medium by discharging the sublimation transfer ink onto the transfer medium with an inkjet head. In this case, the coloring process is, for example, a process performed during or after transfer from the transfer medium to another medium. With this configuration, for example, when sublimation transfer ink is used, it is possible to appropriately predict the color after the color development process. In this case, it is not necessary to actually perform transfer or color development processing when predicting colors. In this case, for example, it is conceivable to perform the actual printing operation separately after the color prediction. For example, when color prediction is performed during the actual printing operation, for example, color transfer may be actually performed after color prediction. Further, ink other than sublimation transfer ink may be used as ink that develops color by color development processing. In this case, for example, it is conceivable to use an ink containing a dye (for example, reactive dye or the like) that requires a coloring process as a coloring material. Further, in this configuration, the color information is information indicating the amount of ink ejected to each position of the medium to be ejected based on image data, for example, for each color ink of a plurality of colors. If comprised in this way, the prediction of the color after color development processing can be performed more appropriately, for example.

  In this case, for example, it is conceivable to use C (cyan), M (magenta), Y (yellow), and K (black) inks as the plurality of colors of ink. The CMYK inks are, for example, inks that become CMYK colors after performing color development processing. In this case, as the color information, for example, information indicating a color in the color space of the CMYK color system can be suitably used. If comprised in this way, high-definition printing, such as a full color, can be appropriately performed by using the ink of each color of CMYK, for example. In this case, by using the color information as described above, it is possible to more appropriately predict the color after the coloring process.

  Further, in the color prediction stage, for example, it is conceivable to predict the color after the color development processing using the color development prediction data created in advance. Further, as the color prediction data, for example, data that associates at least colors before and after the color development process in advance can be suitably used. More specifically, the color prediction data includes, for example, data in which the Lab value corresponding to the color before color development processing and the color information are associated with the Lab value corresponding to the color after color development processing. It is possible to use it. More specifically, in this case, it is conceivable to use ICC profile data as the color development prediction data. The ICC profile data is, for example, data created according to the specification of the ICC profile. In this case, as color information, for example, information in which a value corresponding to each color of CMYK is set is used. Then, as the color prediction data, for example, the Lab value corresponding to the color before the color processing and the color information are combined with three values indicating the Lab value and four values consisting of values corresponding to each color of CMYK. Data including at least seven values is used. If comprised in this way, the prediction of the color after color development processing can be performed more appropriately, for example. In this case, the color prediction data can also be considered as, for example, an ICC profile for color prediction.

  In addition, when color printing is performed by the ink jet method, usually, inks of a plurality of colors are ejected to the same position (ejection position) of the medium as needed according to the color to be expressed. In this case, for the color after the color development process, for example, a certain amount of difference may occur depending on the order in which dots of a plurality of colors of ink overlap at the same position. Therefore, in the color prediction stage, for example, the color after the color forming process may be predicted in consideration of the order in which the dots of the inks of a plurality of colors overlap at the same position on the ejection target medium. If comprised in this way, the prediction of the color after color development processing can be performed more appropriately, for example. In addition, depending on the required printing quality, the order in which different color inks overlap at the same position may be set to a certain order so that no difference occurs depending on the position of the medium. In this case, in the ink ejection stage, the inks of a plurality of colors are ejected onto the medium to be ejected by the inkjet head so that the order in which the dots of the inks of the plurality of colors overlap at the same position on the medium to be ejected is a constant order. Even in such a configuration, the color after the color development process can be predicted more appropriately.

  In addition, as a configuration of the present invention, for example, a printing method (inkjet printing method) for performing printing using the color prediction method (inkjet color prediction method) described above can be considered. In this case, for example, the printing data preparation stage, the printing data correction stage, and the printing execution stage are performed to perform printing by the inkjet method. In this case, the print data preparation step is a step of preparing print data indicating an image to be printed, for example. The print data correction step is a step of correcting print data based on a color prediction result obtained by performing color prediction using the color prediction method described above. In addition, the printing execution stage is, for example, a stage in which ink is ejected to a printing medium that is a medium to which ink is ejected when printing is performed. In this case, in the printing execution stage, for example, a discharge operation for discharging a plurality of colors of ink to the printing medium based on the printing data corrected in the printing data correction stage, and a coloring process for coloring the ink are performed. Do. According to this configuration, for example, it is possible to appropriately eject ink onto the printing medium while appropriately predicting the color after the coloring process.

  In this case, as the print data, for example, data different from the image data used when predicting the color after the color development process may be used. More specifically, when color prediction is performed using the color prediction method described above, for example, data indicating a preset pattern can be used as the image data. In this case, for example, data indicating a predetermined test pattern (color chart or the like) is used as the image data. In this case, in the print data preparation stage, data indicating the desired image to be printed (data for actual printing) is prepared as print data, so that an image different from the image data for color prediction can be obtained. Prepare the print data shown. If comprised in this way, a desired image can be printed appropriately based on the prediction result of a color, for example. Further, as the print data, for example, it is conceivable to use data indicating the same image as the color prediction image data. In this case, for example, the color after color development processing is predicted using image data indicating an image for actual printing. Even in such a configuration, a desired image can be appropriately printed based on, for example, a color prediction result.

  In this configuration, in the print data preparation stage, it is conceivable to prepare halftone dot data generated by, for example, halftone processing as print data. In this case, at the print data correction stage, for example, the print data is corrected by changing some of the dots constituting the dot data used as the print data. Further, in this case, for example, based on the color prediction result, the print data is corrected so that the color after the color development processing approaches the desired color for the image printed in the printing execution stage. If comprised in this way, correction | amendment of print data can be performed appropriately, for example. In this configuration, it is also conceivable to use, for example, an inkjet head capable of discharging a plurality of types of ink droplets at the printing execution stage. In this case, in the print data correction stage, for example, by changing some of the dots constituting the halftone dot data, the volume of ink droplets discharged to some of the discharge positions on the printing medium is changed in the print execution stage. As described above, the print data is corrected. With this configuration, for example, when an inkjet head capable of ejecting a plurality of types of ink droplets is used, print data can be corrected appropriately.

  Further, as an operation performed in accordance with the color prediction result after the color development processing, an operation other than the correction of the print data may be performed. In this case, for example, it is conceivable to adjust the conditions of the color development process based on the color prediction result after the color development process. More specifically, in this case, in the ink jet printing method, it is conceivable to perform operations in the coloring condition setting stage and the printing execution stage. In this case, the coloring condition setting step is a step of setting the coloring processing conditions based on the color prediction result obtained by performing color prediction using the color prediction method described above, for example. In this case, in the printing execution stage, for example, a discharge operation for discharging a plurality of colors of ink onto a printing medium and a coloring process for coloring the ink using the coloring process conditions set in the coloring condition setting stage are performed. . Even in such a configuration, a desired image can be appropriately printed based on, for example, a color prediction result.

  According to the present invention, for example, when printing is performed by an inkjet method using ink that develops color by color development processing, the color after color development processing can be appropriately predicted.

It is a figure explaining printing device 10 concerning one embodiment of the present invention. FIG. 1A shows an example of the configuration of the main part of the printing apparatus 10. FIG. 1B shows an example of the printing operation performed in this example. It is a flowchart which shows an example of the operation | movement which performs color prediction. 6 is a flowchart illustrating an example of a printing operation performed in this example. 10 is a flowchart illustrating a modified example of a printing operation.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a printing apparatus 10 according to an embodiment of the present invention. FIG. 1A shows an example of the configuration of the main part of the printing apparatus 10. Except as described below, the printing apparatus 10 may have the same or similar features as a known inkjet printer. For example, the printing apparatus 10 may further have the same or similar configuration as each part of a known inkjet printer in addition to the configuration of the main part described below.

  In this example, the printing apparatus 10 is an ink jet printer that performs printing by an ink jet method, and printing operation is performed by ejecting ink (ink droplets) to a transfer medium 50 used as a medium (medium) from which ink is ejected. Run at least part of. The transfer medium 50 is a medium used for transferring an image to another medium, for example. As the transfer medium 50, a known transfer paper or the like can be suitably used. The printing operation is, for example, an operation for creating a print product. In this example, as will be described in detail later, after performing an operation of drawing an image on the transfer medium 50 using the printing apparatus 10, an image on the transfer medium that is an example of another medium is displayed. By performing the transfer, a final print product is created. As a configuration for performing such an operation, in this example, the printing apparatus 10 includes a head unit 12, a platen 14, a scan driving unit 16, and a control unit 20.

  The head unit 12 is configured to eject ink toward the transfer medium 50. In this example, the head unit 12 includes a carriage 100, a plurality of inkjet heads 102 c to 102 k, and a colorimeter 104. The carriage 100 is a holding member that holds other components of the head unit 12. The plurality of inkjet heads 102c to 102k are ejection heads that eject inks of different colors by an inkjet method. More specifically, the inkjet head 102c discharges C (cyan) ink. The inkjet head 102m discharges M (magenta) color ink. The inkjet head 102y discharges Y (yellow) color ink. The inkjet head 102k discharges K (black) ink. In this case, each color ink of CMYK is an example of different colors of ink.

  In this example, sublimation transfer ink is used as the ink of each color of CMYK. The sublimation transfer ink is a sublimation ink used when printing is performed by a transfer method. The sublimation ink is, for example, an ink that develops a predetermined color by sublimating ink components by heating. The sublimation ink can be considered as, for example, ink that dyes a medium by sublimating ink components. Further, in this example, the sublimation transfer ink of each color used in the inkjet heads 102c to 102k is an example of an ink that develops color by a color development process. In this case, the ink color refers to the color of the ink obtained after the color development process. Therefore, the CMYK color inks can be considered as, for example, the inks that become the CMYK colors after the coloring process. In this example, a known sublimation transfer ink can be suitably used as the CMYK ink.

  The color measuring device 104 is a measuring device that measures the color of an image drawn on the transfer medium 50, and is used when color prediction, which will be described in more detail later, is performed. As the colorimeter 104, a known colorimeter can be suitably used. In this example, the colorimeter 104 is held by the carriage 100 together with the inkjet heads 102c to 102k. With this configuration, for example, the color of the image drawn on the transfer medium 50 can be appropriately measured without removing the transfer medium 50 from the printing apparatus 10. In this case, for example, the color may be measured in parallel with the operation of ejecting ink by the ink jet heads 102c to 102k. Further, in a modified example of the configuration of the printing apparatus 10, the colorimeter 104 may be disposed outside the head unit 12 without being held by the carriage 100.

  The scanning driving unit 16 is a driving unit that causes the head unit 12 to perform a scanning operation that moves relative to the transfer medium 50. In this case, letting the head unit 12 perform the scanning operation means, for example, causing the inkjet heads 102c to 102k in the head unit 12 to perform the scanning operation. In this example, the scanning drive unit 16 causes the head unit 12 to perform a main scanning operation and a sub-scanning operation as a scanning operation. In this case, the main scanning operation is, for example, an operation of ejecting ink (ink droplets) while moving in the main scanning direction set in advance in the printing apparatus 10. In this example, the scanning drive unit 16 performs main scanning operation on the head unit 12 by causing the inkjet heads 102c to 102k to eject ink while moving the head unit 12 in the main scanning direction indicated by an arrow in the drawing. Make it. In this case, the scan driving unit 16 causes each of the inkjet heads 102c to 102k to eject ink at a timing set according to an image drawn on the transfer medium 50, for example. The sub-scanning operation is, for example, an operation that moves in the sub-scanning direction orthogonal to the main scanning direction. For example, the scanning drive unit 16 moves the head unit 12 relative to the transfer medium 50 by conveying the transfer medium 50 in a conveyance direction parallel to the sub-scanning direction, and performs a sub-scanning operation on the head unit 12. To do. Further, the scan driving unit 16 sequentially changes the position of the transfer medium 50 facing the head unit 12 by causing the head unit 12 to perform a sub-scanning operation between main scanning operations. With this configuration, for example, ink can be appropriately ejected to each position of the transfer medium 50 in accordance with an image to be drawn on the transfer medium 50. Thereby, for example, a desired image can be appropriately drawn on the transfer medium 50. In this case, to draw an image on the transfer medium 50 is to draw an image before the transfer on the transfer medium 50 with ink before performing the coloring process.

  The control unit 20 is a CPU of the printing apparatus 10, for example, and controls the operation of each unit of the printing apparatus 10. According to this example, for example, an image before transfer can be appropriately drawn on the transfer medium 50 using sublimation transfer ink. In this case, as described below with reference to FIG. 1B, for example, the image 60 drawn on the transfer medium 50 is transferred to the transfer medium 52, and the coloring process is performed on the ink during or after the transfer. By performing the above, it is possible to appropriately obtain a printed product. Also, in this example, as will be described in detail later, processing for bringing the color after color development processing closer to a desired color is performed using the result of color prediction performed using the colorimeter 104. . Such correction of data will be described in more detail later.

  FIG. 1B is a diagram illustrating an example of a printing operation performed in this example, and an example of an operation of drawing an image 60 on the transfer medium 50 using the printing apparatus 10 and an operation of a transfer and coloring process performed thereafter. Indicates. Note that, as described above, in this example, processing for bringing the color after the color development processing closer to a desired color is performed using the result of color prediction. However, for convenience of illustration and explanation, in FIG. 1B, such processing is omitted, and an example of each operation is simplified and illustrated. A process for bringing the color after the color development process closer to a desired color will be described in more detail later. Except as described above and below, each operation may be performed in the same or similar manner as a known operation.

  In this example, when a printing operation is performed, the image 60 is drawn on the transfer medium 50 by discharging ink from the inkjet heads 102c to 102k in the printing apparatus 10 to the transfer medium 50 as described above. . In this case, the image 60 on the transfer medium 50 is an image drawn with ink before color development processing. In this example, the image 60 on the transfer medium 50 is an image that is subsequently transferred to a transfer medium 52 that is a medium different from the transfer medium 50.

  In addition, after the image 60 is drawn on the transfer medium 50 by the printing apparatus 10, the transfer medium 52 that is the transfer destination of the image 60 is further used, and the transfer medium 52 on the surface on which the image 60 is drawn on the transfer medium 50. Then, the image 60 is transferred. In this case, for example, the image 60 is transferred from the transfer medium 50 to the transfer medium 52 by applying pressure while heating. In this example, for example, by performing heating at the time of transfer, a color forming process is performed simultaneously with the transfer, and the ink constituting the image 60 is colored. In this case, in the coloring process, for example, the ink is colored by applying pressure or heating according to preset conditions of the coloring process. Further, in a modified example of the printing operation, for example, a color forming process may be separately performed after the transfer. In addition, after the transfer and color development processing is performed, the transfer medium 50 is peeled off from the transfer target medium 52, so that the transfer medium 52 to which the ink after the color development processing is attached remains as a printed product. If comprised in this way, the printing operation using sublimation transfer ink can be performed appropriately.

  Next, the color prediction performed in this example will be described in more detail. As described above, in this example, color prediction is performed using the colorimeter 104 in the printing apparatus 10. In this case, the color prediction is to predict the color after the coloring process for the sublimation transfer ink used in the printing apparatus 10. In this example, the operation for predicting the color is an example of the operation of the color prediction method of the ink jet method for predicting the color printed by the ink jet method.

  More specifically, when using an ink that develops color by color development processing, such as the sublimation transfer ink used in this example, the color finally expressed in the printed product is confirmed until the color development processing is performed. It is not possible. However, depending on the purpose of printing and the like, there are cases where it is required to predict the color after the color development process before the color development process is actually performed. For example, when performing color processing outside the printing apparatus 10, when performing color measurement using a configuration provided in the printing apparatus 10, such as the colorimeter 104 used in this example, the color before the color processing is performed. It may be preferable to measure.

  In addition, when sublimation transfer type ink or the like is used, the ink is usually not colorless at all even before the color forming process is performed. Presents. In this case, in the image drawn on the transfer medium 50, a certain amount of color is expressed even before the color development process is performed. In this case, the color of the image before the color development process can be considered as, for example, a color expressed with a smaller gamut than that after the color development process.

  Therefore, in this example, the color of the image drawn on the transfer medium 50 is measured using the colorimeter 104, and the color is predicted based on the measurement result. In this case, as input information for prediction, in addition to the color before the color development process indicated by the measurement result of the colorimeter 104, what color the color at each position on the transfer medium 50 is. Information indicating whether the ink is represented by a combination of inks is used. In addition, as such information, for example, color information indicating a color designated for each position of an image in image data indicating a color image is used. More specifically, in this example, color prediction is performed by performing an operation as shown in the flowchart of FIG.

  FIG. 2 is a flowchart illustrating an example of an operation for performing color prediction. In this example, when color prediction is performed, as described above, the color of the image drawn on the transfer medium 50 is measured using the colorimeter 104, and color prediction is performed based on the measurement result. I do. Therefore, when color prediction is performed, first, image data indicating an image used for color prediction is prepared (S102). In this example, as this image data, for example, data indicating a dedicated image used for color prediction is prepared. In this case, data indicating a color image is used as the image data. As such image data, for example, data indicating a predetermined test pattern (color chart or the like) can be suitably used. In this case, for example, it is conceivable to separately perform an operation for predicting the color before performing the actual printing operation for obtaining the printed product. Further, in the modified example of the color predicting operation, it is also conceivable to use image data indicating an image used for actual printing instead of using a dedicated image used for color prediction. In this case, for example, an operation for predicting a color may be performed as a part of the operation for performing the actual printing operation.

  Further, after the image data is prepared, the image indicated by the image data is drawn on the transfer medium 50 by ejecting ink according to the image data (S104). In this case, the operation in step S104 is an example of the operation in the ink ejection stage. More specifically, in the operation of step S104, for example, the ink corresponding to the image data is ejected onto the transfer medium 50 by the ink jet heads 102c to 102k based on the image data. Is drawn on the transfer medium 50.

  As described above, in this example, the color after the coloring process is predicted before the actual coloring process is performed. In this case, when the color is predicted, the transfer from the transfer medium 50 to the transfer medium 52 can be omitted. Therefore, the transfer medium 50 used at the time of color prediction can be considered as a medium corresponding to the transfer medium 50 used at the time of actual printing, for example, not a medium for actual transfer. In this case, the medium corresponding to the transfer medium 50 used during the actual printing has, for example, the same characteristics as the transfer medium 50 used during the actual printing, as long as the purpose of predicting the color can be achieved. It is a medium that can be considered. In this example, the transfer medium 50 used for color prediction is an example of a medium to be ejected.

  Further, after the image is drawn on the transfer medium 50, the color of the ink before the color forming process is measured using the colorimeter 104 (S106). In this case, the operation in step S106 is an example of the operation in the color measurement stage. As the operation of measuring the color by the colorimeter 104, for example, an operation of measuring the color of the image drawn on the transfer medium 50 in step S104 can be considered. In this example, in step S104, for example, color measurement is performed for a plurality of positions in the image. More specifically, when an image is drawn on the transfer medium 50 using image data indicating a predetermined test pattern, for example, by measuring the color at a position corresponding to each color set in the test pattern, Measure the color corresponding to the test pattern. In this case, for example, the color indicated in the Lab color system is acquired as the color of the measurement result. Acquiring a color indicated in the Lab color system is, for example, acquiring values corresponding to the L value, a value, and b value indicating the color in the Lab color system.

  Further, after the color measurement, based on the measurement result, the color after the color forming process is performed on the ink adhering to the transfer medium 50 is predicted (S108). In this case, the operation in step S108 is an example of the operation in the color prediction stage. Further, the color after the color forming process is performed on the ink adhering to the transfer medium 50 is, for example, the color after the color forming process is performed at the time of transfer from the transfer medium 50 to the transfer medium 52 or after the transfer. That is. In this case, the color after the color forming process may be a color obtained when the color developing process is performed regardless of whether the color developing process is actually performed. In this example, the color prediction performed in step S108 is performed by, for example, the host PC that is a computer that controls the printing apparatus 10. Further, in the modified example of the operation for predicting the color, the color prediction performed in step S108 may be performed in the printing apparatus 10. In this case, for example, the control unit 20 in the printing apparatus 10 performs a process for prediction.

  In this example, the color prediction is further based on color information indicating the color designated for each position of the image in the image data, in addition to the measurement result of the color before the color development processing measured in step S106. The color after the color development process is predicted. Further, as the color information, for example, information indicating the amount of ink ejected to each position of the transfer medium 50 based on the image data is used for each color of a plurality of colors used in the printing apparatus 10. More specifically, for example, in this example, the color information indicates the ejection amount to each position of the transfer medium 50 for each color ink of CMYK. In this case, each position of the transfer medium 50 is, for example, an ink ejection position set according to the printing resolution. Further, this discharge position may be a designed position. Further, the color information can be considered as information indicating the amount of ink of each color ejected corresponding to each position of the image, for example. The information indicating the amount of ink of each color is, for example, information indicating the ejection amount of each color of a plurality of colors. In addition, indicating the amount of ink of each color ejected corresponding to each position indicates, for example, whether or not ink of each color is ejected to each position.

  In the printing apparatus 10, it is also conceivable to use an inkjet head that can eject a plurality of types of ink droplets as the inkjet heads 102 c to 102 k. In this case, as the ejection amount to each position for each color ink, for example, it is conceivable to further indicate the volume of ink droplets when ink is ejected to each position. Further, the color information can be considered as information indicating how ink of each color is ejected to each position of the medium or the image, for example. In addition, when using CMYK inks as in this example, for example, information indicating colors in a color space of the CMYK color system may be used as the color information. If comprised in this way, the color designated with respect to each position of an image in image data can be shown appropriately, for example.

  Further, in this example, in the color prediction performed in step S108, the color after color generation processing is predicted using color generation prediction data created in advance. In addition, as the color prediction data, for example, data that associates at least colors before and after the color development process is used. In addition, the color prediction data may be created using a plurality of samples (multiple samples) in advance, for example. In this case, for example, the number of samples corresponding to the required accuracy is actually subjected to the color development processing, and the color prediction data is obtained by measuring the color before and after color development, associating with color information, and the like. create.

  More specifically, it is conceivable to use ICC profile data as the color development prediction data. The ICC profile data is, for example, data created according to the specification of the ICC profile. Further, the ICC profile is a series of data characterizing input / output devices and color spaces related to color according to a standard published by the International Color Consortium (ICC) regarding color management, for example. In this case, the color prediction data can also be considered as, for example, an ICC profile for color prediction.

  Further, as such color prediction data, for example, data in which Lab values and color information corresponding to colors before color processing and Lab values corresponding to colors after color processing are associated are used. Conceivable. Further, as the color information, for example, it is conceivable to use information in which values corresponding to CMYK colors are set. In this case, as the Lab value and color information corresponding to the color before the color processing, for example, four values including three values indicating the Lab value corresponding to the color before the color processing and values corresponding to the respective colors of CMYK It is conceivable to use seven values in combination. In this case, the three values indicating the Lab value are the L value, the a value, and the b value that constitute the Lab value. Further, in this case, the color prediction data can be considered as data including at least seven values indicating the Lab value and color information corresponding to the color before the color processing. Further, as the Lab value corresponding to the color after the color development processing, it is conceivable to use three values indicating the Lab value. In this case, the color prediction data includes, for example, seven values indicating the Lab value and color information corresponding to the color before the color processing, and three values indicating the Lab value corresponding to the color after the color processing. It can be considered as ICC profile data or the like associated with each other.

  According to this example, for example, in the case where printing is performed by an ink jet method using ink that develops color by the color development process by further using the color information as described above in addition to the measurement result of the color before the color development process. Therefore, it is possible to predict the color after the coloring process more appropriately with high accuracy. More specifically, for example, as described above, when a sublimation transfer type ink or the like is used, the ink usually exhibits a certain color even in a state before the color forming process is performed. Therefore, if considered simply, it seems that the color after color development can be predicted without using the color information as in this example. However, the inventor of the present application has found through experiments and the like that even if the color expressed by the ink before color development appears close to the color, the color difference may become a large color after color development processing. In this case, if the color after the color development process is predicted based only on the color expressed by the ink before color development without using the color information, the color between the color actually expressed after the color development process is large. Differences are likely to occur. Moreover, such a difference becomes large especially in the case of an achromatic color or a color close to an achromatic color. On the other hand, according to this example, by further using the color information, the color after the color development process can be predicted more accurately with high accuracy. This also makes it possible to more appropriately predict the color after the color development process, for example, before actually performing the color development process.

  Next, the printing operation performed in this example will be described in more detail. As described above, in this example, in the printing operation, a process for bringing the color after the color development process closer to a desired color is performed using the result of color prediction. More specifically, as such processing, data indicating an image to be printed is corrected by an operation as shown in FIG. 3, for example.

  FIG. 3 is a flowchart showing an example of the printing operation performed in this example, and a printing method (inkjet) that performs printing using the color prediction method (color prediction method of the inkjet method) that performs color prediction described above. An example of the operation in the printing method) is shown. In addition, the printing operation described below can be considered as a printing operation that will be described in more detail including items omitted in the description made with reference to FIG. In this example, the printing operation described below is performed after the color prediction operation described with reference to FIG. 2 is performed, for example.

  In this case, in the printing operation, first, print data (data for actual printing) indicating an image to be printed on the transfer medium 50 during actual printing is prepared (S202). In this case, the operation in step S202 is an example of the operation in the print data preparation stage. In this example, as the print data, for example, data different from the image data used at the time of color prediction is used. In this case, the data different from the image data is, for example, data indicating an image different from the image data used for color prediction. More specifically, in the case of this example, as described above, data indicating a predetermined test pattern is used as the image data used for color prediction. On the other hand, as print data, data indicating an image to be expressed in a print product (a desired image to be printed) is used.

  In this example, halftone data generated by halftone processing is prepared as print data. In this case, the halftone data generated by the halftone process is, for example, bitmap data indicating a position at which ink is ejected by the inkjet head. In this case, for example, binary bitmap data may be used as the bitmap data. In this case, halftone dot data is prepared for each color (for example, each color of CMYK) used for printing as print data. Such halftone data may be generated by the same or similar process as a known halftone process performed at the time of printing with an ink jet printer, for example. In this case, the known halftone process is, for example, a process performed in the RIP process. In this case, at the time of halftone processing, conversion is performed to match the resolution indicated by the print data with the resolution at the time of printing (printing resolution) as necessary. Therefore, the print data can be considered as data indicating the state of each pixel of the image with the resolution at the time of printing, for example. In step S202, the print data may be prepared by performing RIP processing on a computer (for example, host PC) outside the printing apparatus 10, for example. In this case, for example, the print data preparation is completed by supplying the generated print data to the printing apparatus 10.

  In addition, as described above, in the modified example of the printing operation, for example, as the image data used when predicting the color, not the data indicating the test pattern or the like, but the same image as the print data for actual printing It is also conceivable to use data indicating. In this case, in step S202, print data indicating the same image as the image data used for color prediction is prepared. In this case, the image data used for color prediction may be used as it is as the actual print data.

  In this example, the print data is corrected based on the color prediction result described with reference to FIG. 2 (S204). In this case, the operation in step S204 is an example of the operation in the print data correction stage. In this example, in step 204, the print data is corrected by changing a part of the dots constituting the halftone dot data used as the print data. In this case, to change a part of dots constituting halftone dot data means, for example, deletion of some dots existing in the halftone dot data before correction, or dots existing in the halftone dot data before correction. Is to add a dot at no position. When such dot deletion is performed, for example, in the print data before correction, it is possible to change the ink discharge position (discharge position) so as not to discharge ink. In addition, when such dots are added, for example, it is possible to change so that ink is ejected from a position where ink is not ejected in the print data before correction. Therefore, with this configuration, the amount of ink ejected to each position of the transfer medium 50 can be changed based on the color prediction result, for example. Further, in this case, by changing the amount of ink of each color ejected to each position, the color after the color development process can be changed to a different color compared to before the correction. Therefore, if constituted in this way, the color after color development processing can be changed variously based on the prediction result of a color, for example. More specifically, in this example, for example, based on the result of color prediction, for the image printed in step S206 described below, the color after color development processing is closer to the desired color. Correct the print data.

  For example, the correction of the print data may be performed by the control unit 20 of the printing apparatus 10. Further, the correction of the print data may be performed by a computer outside the printing apparatus 10 using, for example, a host PC or the like. In this case, in step S202, the print data may be prepared in the host PC or the like, and the print data may be corrected in step S204 without supplying the print data to the printing apparatus 10 at that time. In this case, for example, it is conceivable to directly supply the corrected print data to the printing apparatus 10.

  In addition, after the print data is corrected, ink is ejected onto the actual transfer medium 50, transferred onto the transfer medium 52, and color development processing is performed, thereby completing a print product (S206). . In this case, the operation in step S206 is an example of the operation in the print execution stage. In this case, the production transfer medium 50 is an example of a printing medium that is a medium that is used when the actual printing is executed.

  More specifically, in the operation of step S206 in this example, first, after the correction, the ink jet heads 102c to 102k eject a plurality of colors of ink based on the print data corrected in step S204. An image indicated by the print data is drawn on the transfer medium 50 (S212). In this case, the operation in step S212 is an example of a discharge operation. Also, ejecting a plurality of colors of ink by the ink jet heads 102c to 102k based on the corrected print data corresponds to, for example, dots constituting halftone dot data corresponding to each color for each color used for printing. The ink of each color is ejected to the ejection position by each of the inkjet heads 102c to 102k.

  Then, after the image is drawn on the transfer medium 50, the image is transferred from the transfer medium 50 to the transfer medium 52 in the same or similar manner as that described with reference to FIG. Do. Further, at the time of transfer, heating and pressurization are performed under preset coloring process conditions, whereby the coloring process for the ink is executed and the ink is colored (S214). Further, depending on the characteristics of the ink used, for example, the color forming process may be performed after the transfer, for example, instead of performing the color developing process simultaneously with the transfer.

  If comprised in this way, the printing by the inkjet method using the ink which color-forms by color development processes, such as a sublimation transfer ink, for example can be performed appropriately. In this case, by correcting the print data based on the color prediction result after the color development process, the color after the color development process can be appropriately brought close to the desired color. Therefore, according to this example, for example, it is possible to appropriately perform the necessary correction on the print data while appropriately predicting the color after the coloring process, and appropriately discharge the ink onto the transfer medium 50. . In addition, for example, a desired image can be appropriately printed based on the color prediction result.

  Here, as described above, in this example, the print data is corrected by correcting the halftone data generated by the halftone process. On the other hand, when it is considered that the data is simply corrected, it seems that the data before the halftone process may be corrected. In fact, it is considered that the color after the coloring process can be adjusted even when the data before the halftone process is corrected. However, when data before halftone processing is used, each pixel of the image indicated by the data usually does not directly correspond to the position at which the inkjet heads 102c to 102k eject ink. For this reason, when such data correction is performed, it is not usually possible to easily predict how the position of ejecting each color ink changes after the correction. In this case, it may be difficult to sufficiently predict the state in which ink is ejected based on the corrected data. As a result, it may be difficult to appropriately predict how the color after the color development process changes due to data correction.

  On the other hand, the halftone data generated by the halftone process can be considered as data directly corresponding to the position at which each color ink is ejected. In this case, it is possible to more reliably predict how the position of ejecting each color ink changes after correction. As a result, it is possible to more appropriately predict how the color after the color development process is changed by correcting the data. Further, when correcting halftone dot data, it is possible to perform correction only by deleting or adding a part of dots, so that it is possible to reduce the amount of processing necessary for correction. Therefore, according to this example, for example, it is possible to more appropriately correct print data.

  Further, as described above, as the ink jet heads 102c to 102k, for example, it is conceivable to use ink jet heads capable of ejecting a plurality of types of ink droplets. In this case, it is conceivable to prepare halftone dot data for each ink droplet volume as halftone dot data for each color in the print data. In this case, as the halftone dot data for each capacity, for example, it is conceivable to use binary bitmap data indicating the position at which the corresponding capacity of ink is ejected. When the print data is corrected in step S204, for example, the transfer medium 50 is changed in step S212 by changing a part of dots constituting halftone dot data corresponding to at least a part of the capacity (ink droplet capacity). The print data is corrected so as to change the volume of ink droplets ejected to a part of the ejection positions. If comprised in this way, when using the inkjet heads c-k which can discharge the ink droplet of multiple types of capacity | capacitance, for example, correction | amendment of print data can be performed appropriately.

  In addition, as described above, in this example, after color prediction is performed by the operation described with reference to FIG. 2, actual printing is performed by the operation described with reference to FIG. . In this case, after performing the color prediction once, the present application may be printed a plurality of times. More specifically, for example, based on a prediction result obtained by performing color prediction once using one transfer medium 50, a plurality of actual printings are performed using a plurality of transfer media 50 and a plurality of transfer target media 52. May be performed. If comprised in this way, the several printed product can be produced efficiently, for example.

  In the above description, as an example of the operation performed in accordance with the color prediction result after the color development processing, an example of the operation in the case of correcting print data has been mainly described. Further, in a modified example of the printing operation, an operation other than the correction of the print data may be performed as an operation performed in accordance with the color prediction result after the coloring process. In this case, for example, it is conceivable to adjust the conditions of the color development process based on the color prediction result. More specifically, when sublimation transfer ink or the like is used, the color after color development usually varies depending on the conditions of color development processing. Therefore, it is possible to adjust the color after the color development process by adjusting the color development condition according to the color prediction result without necessarily correcting the print data.

  FIG. 4 is a flowchart showing a modified example of the printing operation, and shows an example of the operation in the case where the coloring condition is adjusted according to the color prediction result. Except as described below, the printing operation in this modification is the same as or similar to the printing operation described with reference to FIGS. More specifically, also in this modification, the color after the color development process is predicted in the same or similar manner as described with reference to FIGS.

  Also in the operation of the flowchart shown in FIG. 4, print data is prepared in the same or similar manner to the operation in step S202 in the operation described with reference to FIG. 3 (S202). Further, in this modification, after that, as the operation to be performed according to the color prediction result after the color development process, the condition of the color development process is set (S220). In this case, the operation in step S220 is an example of the operation in the coloring condition setting stage. More specifically, in step S220, conditions for color development processing are set based on the color prediction result predicted by the color prediction operation described with reference to FIG. In this case, setting the conditions for the coloring process means, for example, setting the heating temperature, the heating time, and the like during the coloring process. Further, when the color forming process is performed while pressure is applied, for example, when the color forming process is performed simultaneously with the transfer, a pressure of pressurization may be further set as a condition for the color developing process. In this case, for example, it is conceivable to set conditions for the color development process based on condition changing data that predetermines how to change the conditions. As the data for changing the condition, for example, it is conceivable to use data based on the results measured in advance by coloring the ink under various coloring processing conditions.

  Further, in this modification, the operation is the same as or similar to the operation in step S206 described with reference to FIG. 3 except that the print data is not corrected and the color processing conditions set in step S220 are used. Ink is discharged onto the transfer medium 50, and thereafter, image transfer from the transfer medium 50 to the transfer medium 52 and color development processing are performed (S206). In this case, the coloring process is performed using the coloring process conditions set in step S220. If comprised in this way, based on the color prediction result, the color after color development processing can be appropriately brought close to a desired color. In addition, for example, a desired image can be appropriately printed based on the color prediction result.

  The operation of this modification can be considered as an operation of appropriately adjusting the color after the coloring process in a subsequent process performed after ejecting ink onto the transfer medium 50, for example. Further, in a further modification of the printing operation, for example, both correction of print data and setting of conditions for color development processing may be performed based on the result of color prediction. In this case, in addition to the operation of step S204, the operation of step S220 in the flowchart shown in FIG. 4 may be further performed between the operation of step S202 and the operation of step S206 in the flowchart shown in FIG. . Even in such a configuration, for example, based on the color prediction result, it is possible to appropriately approximate the color after the color development processing to a desired color.

  Subsequently, supplementary explanations regarding each component described above will be given. For convenience of explanation, each configuration described above is simply referred to as this example below.

  As described above, in this example, in addition to the color before the color forming process indicated by the measurement result of the colorimeter 104, the color specified for each position of the image in the image data is used. By further using the color information shown, the color after the color development process is predicted. However, when color prediction with higher accuracy is to be performed, it is preferable to perform color prediction in consideration of how to express the color by the inkjet method. More specifically, when performing color printing by the ink jet method, usually, a plurality of colors of ink are applied to the same position (ejection position) of a medium such as the transfer medium 50 according to the color to be expressed as necessary. Discharge. In this case, ejecting a plurality of colors of ink as necessary according to the color to be expressed is, for example, ejecting a plurality of colors of ink to be mixed according to the color to be expressed. Further, the same position of the medium means, for example, the same position in design. Also, the position at which ink is ejected on the medium is, for example, an ejection position set according to the printing resolution.

  In this case, for the color after the coloring process, for example, a certain difference may occur depending on the order in which the dots of the inks of a plurality of colors overlap at the same position. Therefore, in order to predict the color after the coloring process with higher accuracy, for example, the color after the coloring process is performed in consideration of the order in which the dots of a plurality of color inks overlap at the same position on the transfer medium 50. It is preferable to perform prediction. In this case, it is conceivable to use information that further indicates the order in which the inks of a plurality of colors overlap at each position of the image as the color information. Further, when predicting colors, based on color information, color prediction is further performed based on the order in which inks of a plurality of colors overlap at the same position. If constituted in this way, prediction of a color after color development processing can be performed more appropriately with higher accuracy, for example.

  In addition, depending on the required printing quality, for example, when the color is predicted and during the actual printing, the order in which the inks of different colors overlap at the same position may be constant so that no difference occurs depending on the position on the transfer medium 50. It is possible to consider only the order. In this case, during the operation of ejecting each color ink from the inkjet heads 102 c to 102 k to the transfer medium 50, the inks are arranged so that the order in which the dots of the inks of a plurality of colors overlap at the same position on the transfer medium 50 is a constant order. It is possible to discharge. Even in such a configuration, for example, the color prediction after the color development process can be more appropriately performed with higher accuracy.

  More specifically, in this case, for example, it is conceivable that the direction of movement of the inkjet heads 102c to 102k during the main scanning operation is set to only one preset direction. If comprised in this way, the order which the dot of the ink of a several color overlaps can be arrange | equalized appropriately, for example. As another method, for example, with respect to the arrangement of the ink jet heads 102c to 102k, the ink jet heads 102c to 102k are arranged so that the positions in the sub scanning direction do not overlap with each other. It is also possible to install it. In this case, for each position of the transfer medium 50, each of the inkjet heads 102c to 102k ejects ink by main scanning operations that are different from each other. Therefore, also in this case, the order in which the dots of the inks of a plurality of colors overlap can be appropriately aligned.

  In addition, as described above, in this example, sublimation transfer ink is used as the ink that develops color by the coloring process. However, when the color prediction and the printing operation described above are considered in a more general manner, an ink other than the sublimation transfer ink may be used as the ink that develops color by the color development process. More specifically, as such an ink, for example, it is conceivable to use an ink containing, as a coloring material, a dye (for example, a reactive dye) that requires a coloring process. Even in such a case, the color information can be predicted more appropriately by using the color information in the same manner as described above. Also in this case, for example, by correcting the print data or adjusting the coloring condition according to the color prediction result, the color after the coloring process can be appropriately brought close to the desired color during the actual printing. it can. When ink other than the sublimation transfer type ink is used, for example, the printing apparatus 10 may directly eject ink to a medium that is a print product, and the printing operation may be performed without performing the transfer. .

  The present invention can be suitably used in, for example, an inkjet color prediction method and an inkjet printing method.

DESCRIPTION OF SYMBOLS 10 ... Printing apparatus, 12 ... Head part, 14 ... Platen, 16 ... Scanning drive part, 20 ... Control part, 50 ... Transfer medium, 52 ... Transfer medium, 60 ... Image, 100 ... Carriage, 102 ... Inkjet head, 104 ... Colorimeter

Claims (13)

An ink jet color prediction method for predicting a color printed by an ink jet method,
This is a step of ejecting ink onto a medium to be ejected, which is a medium on which ink is ejected. An ink discharge step of drawing an image corresponding to the image data on the discharge medium by discharging to the discharge medium;
A step of measuring the color of the ink before color development processing is performed, and a color measurement step of measuring the color of the image drawn on the discharged medium in the ink discharge step;
A color prediction stage for predicting the color after color development processing is performed on the ink;
In the color prediction step, based on the color information indicating the color designated for each position of the image in the image data, and the color measurement result before the color development processing measured in the color measurement step, the color development processing A color prediction method of an ink jet method, wherein color prediction after performing is performed. In the ink ejection stage, sublimation transfer ink is used as the ink that develops color by the color development process, and a transfer medium that is a medium used when transferring an image to another medium is used as the ejection target medium,
2. The color prediction method according to claim 1, wherein the color development process is a process performed during or after transfer from the transfer medium to the other medium.   3. The color information is information indicating an amount of ink ejected to each position of the ejection target medium based on the image data for each color of the plurality of colors. The color prediction method of the inkjet method as described in 2. C, M, Y, and K inks are used as the plurality of colors of ink.
4. The color prediction method according to claim 1, wherein the color information is information indicating a color in a color space of a CMYK color system. In the color prediction step, at least the color before and after the color development process is used to predict the color after the color development process using the color prediction data that is associated in advance,
2. The color prediction data used is data in which a Lab value corresponding to a color before color development processing and the color information are associated with a Lab value corresponding to a color after color development processing. To 4. The color prediction method of the ink jet method according to any one of items 1 to 4. The color prediction data is ICC profile data,
The color information is information in which a value corresponding to each color of CMYK is set.
As the Lab value and color information corresponding to the color before the color development processing, data including at least seven values including three values indicating the Lab value and four values including values corresponding to the colors of CMYK. The color prediction method of the ink jet method according to claim 5, wherein the color prediction method is used.   2. The color prediction after the color development processing is performed in the color prediction step in consideration of the order in which the dots of the plurality of colors of ink are overlapped at the same position of the ejection target medium. The color prediction method of the inkjet method in any one of from 6.   In the ink ejection step, the ink of the plurality of colors is ejected onto the medium to be ejected by the inkjet head so that the order in which the dots of the ink of the plurality of colors overlap at the same position of the medium to be ejected is a fixed order. The color prediction method of the ink jet method according to claim 1, wherein An inkjet printing method for performing printing by an inkjet method,
A print data preparation stage for preparing print data indicating an image to be printed;
A print data correction step of correcting the print data based on a color prediction result obtained by performing color prediction using the ink-jet color prediction method according to claim 1;
A printing execution stage for discharging ink to a printing medium that is a medium to which ink is discharged when printing is performed;
In the printing execution step,
An ejection operation for ejecting a plurality of colors of ink to the printing medium based on the print data corrected in the print data correction stage;
An ink-jet printing method characterized by performing a coloring process for developing ink. In the print data preparation step, halftone data generated by halftone processing is prepared as the print data,
10. The ink jet printing method according to claim 9, wherein in the print data correction step, the print data is corrected by changing a part of dots constituting halftone dot data used as the print data. In the printing execution stage, as the inkjet head, an inkjet head capable of ejecting a plurality of types of ink droplets is used.
In the print data correction step, by changing a part of the dots constituting the halftone dot data, the volume of ink droplets discharged to a part of the discharge positions in the discharge medium is changed in the print execution step. The inkjet printing method according to claim 10, wherein the print data is corrected. An inkjet printing method for performing printing by an inkjet method,
A coloring condition setting stage for setting a coloring process condition based on a color prediction result obtained by performing color prediction using the color prediction method of the ink jet method according to claim 1;
A printing execution stage for discharging ink to a printing medium that is a medium to which ink is discharged when printing is performed;
In the printing execution step,
An ejection operation for ejecting a plurality of colors of ink onto the printing medium;
An ink-jet printing method comprising: performing a coloring process for coloring an ink using the coloring process conditions set in the coloring condition setting step. In the case of performing color prediction using the color prediction method of the ink jet method according to any one of claims 1 to 8, data indicating a preset pattern is used as the image data,
13. The ink jet printing method according to claim 9, wherein in the print data preparation step, data indicating an image different from the image data is prepared as the print data.

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