JP2007074484A - Calibration method, calibration system, calibration program and recording medium with the calibration program stored - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a calibration method, a calibration system, a calibration program which can exactly calibrate the color output characteristics of a printer, with high convenience for a user, and to provide a recording medium with the program stored thereon. <P>SOLUTION: A calibration patch sheet for color calibration and a reference patch sheet used as reference of the color calibration are photographed once, in a state of being piled up. The output characteristics of the printer which prints the calibration patch sheet are calibrated, by comparing a color of a patch included in a color calibration information part CD of the calibration patch sheet with a color of a patch, included in a color calibration information part KCD of the reference patch sheet. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  Conventionally, when calibrating the color output characteristics of a printer, by comparing the result of reading a patch sheet, which is a reference for calibration, with the result of reading the patch sheet output by the printer into the scanner, Is going. Specifically, the user sets the correction amount while comparing the two patch sheets, or obtains the correction amount for reducing the color difference between the two patch sheets from the colorimetric values obtained by reading the patch sheet with a reading device such as a scanner. Is calibrated.

  Further, in order to reduce the influence of patch sheet reading errors, the reference patch sheet and the patch sheet output by the printer may be read and compared in one operation of the scanner (see, for example, Patent Document 1). ). In this way, the influence of variations in shooting is reduced, so that more accurate calibration can be performed.

Japanese Patent No. 3624947

  However, the technique described in Patent Document 1 assumes a scanner as a device for reading an image, and does not consider reading with a device having excellent portability such as a digital camera. In general, since the scanner is used in a stationary state, it is necessary to install the printer in a location where the scanner can be connected when attempting to calibrate using the scanner. This also reduces the degree of freedom for installing the printer, which may be inconvenient for the user. For example, if you have a portable printer that is portable and has a size and weight that can read and print image data recorded on a memory card without connecting to a PC, you can install the printer anywhere. It is desirable to be able to proofread and print at the place.

  SUMMARY An advantage of some aspects of the invention is to provide a calibration method, a calibration system, a calibration program, and a recording medium on which the program is recorded, which can accurately calibrate the color output characteristics of the printer and is highly convenient for the user. .

  In order to solve the above-described problem, the calibration method of the present invention uses a reference patch sheet including a color patch serving as a reference for calibration and a calibration patch sheet including a patch printed by the printing unit. A calibration method for calibrating output characteristics, wherein a reference patch sheet and a calibration patch sheet are photographed at once by an image photographing means, and an image photographing process for generating image data representing the reference patch sheet and the calibration patch sheet, and the image data A patch acquisition step for acquiring the color of the patch included in the reference patch sheet and the color of the patch included in the calibration patch sheet, and the color of the patch included in the reference patch sheet and the color of the patch included in the calibration patch sheet. A calibration information generating step for generating calibration information for calibrating the color output characteristics of the printing means by comparing, and That.

  According to this configuration, the color of the patch having the reference color and the color of the patch printed by the printing unit are acquired from the image data generated by the image photographing unit at a time. Thus, the influence of the variation in the color becomes small, and the color output characteristic of the printing apparatus can be accurately calibrated. Moreover, since the image is taken by an image taking means such as a digital camera, the place where the image is taken and calibrated is not limited, which is convenient for the user.

  Here, it is preferable that the reference patch sheet has an opening window in an area corresponding to the patch of the calibration patch sheet, and that the image is captured in a state where the reference patch sheet is superimposed on the calibration patch sheet.

  In this way, by overlaying the reference patch sheet on the calibration patch sheet, the patch of the calibration patch sheet is photographed through the opening window of the reference patch sheet. Can be generated.

  Here, in the calibration patch sheet, it is preferable that patches of the same color are arranged at a plurality of positions, and in the calibration information generation step, calibration information is generated using a plurality of patches of the calibration patch sheet.

  In this way, by using patches of the same color arranged at a plurality of positions, it is possible to obtain calibration information in which the influence of in-plane errors in printing and photographing is suppressed. Therefore, the color output characteristics of the printing means can be calibrated more accurately.

  Here, in the calibration information generation step, the calibration patch sheet includes print management information relating to the printing conditions of the calibration patch sheet, and the reference patch sheet includes print management information relating to the printing conditions to be calibrated for the reference patch sheet. In this case, when the printing condition indicated by the printing management information of the calibration patch sheet corresponds to the printing condition indicated by the printing management information of the reference patch sheet, it is preferable to generate the calibration information regarding the printing condition.

  In this way, since the calibration information is generated using the calibration patch sheet printed under the printing condition that is the calibration target of the reference patch sheet, the reference patch sheet and the calibration patch sheet that correctly corresponds to the printing condition are generated. By using it, it can be calibrated correctly.

  Here, the calibration patch sheet has a patch in which at least one of the color and the position arranged on the calibration patch sheet is associated with the print management information, and the print management information is based on at least one of the color or position of the patch. It is preferable to further include a print management information acquisition step for acquiring the print management information.

  In this way, since the patch that associates the print management information with the color or position is included in the calibration patch sheet, it becomes difficult to obtain the print management information from the calibration patch sheet. That is, confidentiality can be given to the print management information included in the calibration patch sheet.

  Here, it is preferable to further include a correction step of correcting the shape of the image areas of the reference patch sheet and the calibration patch sheet from the image data.

  In this way, it is possible to correct a change in the shape of the image area of the reference patch sheet and the calibration patch sheet due to the inclination of the image photographing means at the time of photographing. Therefore, even if an image used for calibration is captured by an image capturing means such as a digital camera, it can be accurately calibrated.

  The present invention can also be a calibration system. That is, a calibration system that calibrates the color output characteristics of a printing unit that prints a calibration patch sheet, using a reference patch sheet that includes a patch of a color that serves as a calibration reference and a calibration patch sheet that includes a patch printed by the printing unit Image capturing means for capturing the reference patch sheet and the calibration patch sheet at a time and generating image data representing the reference patch sheet and the calibration patch sheet, and the color of the patch included in the reference patch sheet from the image data, The color output characteristics of the printing means by comparing the patch obtaining means for obtaining the color of the patch contained in the calibration patch sheet and the color of the patch contained in the reference patch sheet and the color of the patch contained in the calibration patch sheet. Calibration information generating means for generating calibration information for calibrating.

  Furthermore, the present invention can be a calibration program or a recording medium. That is, the calibration program of the present invention calibrates the color output characteristics of the printing unit using a reference patch sheet including a patch having a color serving as a calibration reference and a calibration patch sheet including a patch printed by the printing unit. A calibration program for reading image data from a recording medium on which image data obtained by photographing a reference patch sheet and a calibration patch sheet at once by an image photographing unit is recorded in a computer and stored in a storage unit A patch acquisition step for acquiring the color of the patch included in the reference patch sheet and the color of the patch included in the calibration patch sheet from the image data read out from the storage unit, and the color of the patch in the reference patch sheet and the calibration patch Calibration information that calibrates the color output characteristics of the printing means is generated by comparing the color of the patch on the sheet. Characterized in that to execute a calibration information generation step. As a recording medium on which this program is recorded, various computer-readable media such as a flexible disk, a CD-ROM, an IC card, and a memory card can be used.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a calibration system according to the present embodiment. As shown in FIG. 1, the calibration system 1 includes a printer 2 and a digital camera 3. The image data captured by the digital camera 3 can be exchanged with the printer 2 via the memory card 4. However, the printer 2 and the digital camera 3 may be connected so as to be able to exchange data by a cable such as USB or wireless communication.

  The calibration system 1 shoots a calibration patch sheet printed by the printer 2 with a digital camera 3 and calibrates the color output characteristics of the printer 2 using image data obtained by shooting. Hereinafter, the printer 2 which is a characteristic part of the calibration system 1 will be described.

  As shown in FIG. 1, the printer 2 presents to a user a controller 10 that controls the operation of the entire printer 2, a print engine 11 that executes printing using color toners of CMYK as color materials in accordance with the control of the controller 10. And a display panel 12 which is a liquid crystal panel for displaying messages and the like. The printer 2 may be various printing apparatuses such as an ink jet printer, a copying machine, and a fax machine. In the present embodiment, the printer 2 will be described as a laser printer. Also, the toner types are not limited to four colors of C (cyan), M (magenta), Y (yellow), and K (black), but R (red), G (green), B (blue), and the like. But you can. In addition, in the case of an inkjet printer, a configuration in which LC (light cyan), LM (light magenta) ink, or the like is further added to CMYK can be used.

  The controller 10 includes a CPU 13, a ROM 14, a RAM 15, and an external memory interface (hereinafter referred to as an external memory I / F) 16, and the respective components are connected so as to be able to exchange data.

  The CPU 13 is a central part of processing performed by the printer 2. The ROM 14 is a non-volatile memory that can read and write data, such as a flash ROM and an EEPROM, and stores various tables and programs to be described later. The RAM 15 is a general-purpose memory used as a working memory for various processes.

  The external memory I / F 16 is a part that controls reading and writing of data with respect to the memory card 4.

  Next, processing performed by the controller 10 will be described. As shown in FIG. 1, the controller 10 is roughly divided into a patch sheet data generation unit 20 that generates patch sheet data, a print processing unit 30 that prints a calibration patch sheet according to the patch sheet data, and a printed calibration patch sheet. Processing as the color calibration unit 40 for performing color calibration is performed.

  First, the calibration patch sheet generated by the patch sheet data generation unit 20 will be described. FIG. 2 shows an example of a calibration patch sheet. As shown in FIG. 2, the calibration patch sheet is a patch corresponding to print management information indicating a color calibration information portion CD in which calibration patches for obtaining color calibration information are arranged, and printing conditions at the time of printing the calibration patch sheet. The print management information part PD in which is arranged is arranged in the center part of the calibration patch sheet.

  In the color calibration information portion CD, a large number of patches composed of rectangular areas expressing one gradation and one color are arranged for combinations of multiple gradations and a plurality of colors. For example, patches for each condition in which the toner recording rate per unit area is “3%”, “5%”,..., “100%”, K, C, M, and Y toner colors are arranged. Has been. However, the shape and number of patches are not limited to this. For example, the patch may have a circular shape, and a plurality of patches of the same gradation and color may be used to improve the reliability of calibration. You may make it arrange | position.

  The print management information portion PD is configured by arranging a large number of management blocks B so as to surround the color calibration information portion CD. Further, the number of management blocks included in one patch sheet is determined in advance. For example, in FIG. 2, the number of management blocks B is determined to be “n” so that one patch sheet includes management blocks B1 to Bn.

  FIG. 3 is a diagram showing the configuration of the management block B. As shown in FIG. 3, one management block B is divided into vertical and horizontal 4 × 4 matrix areas, and patches can be arranged in each divided area. Further, in the management block B, numbers “1 to 4” are assigned in order in the row direction (x direction) and the column direction (y direction) of the divided areas, so the position of the arranged patch is the row direction. And a number in the column direction.

  The patches arranged in the management block B are generated so that the color and position of the patches correspond to the print management information. Therefore, the patch arranged in the management block B is hereinafter referred to as “management patch”. The print management information includes “product model number” and “manufacturing number” regarding the printer 2, “printing resolution” regarding “printing conditions for printing performed by the printer 2”, “type of processing method such as color conversion processing / halftone processing”, and the like. An example is information indicating “paper type”.

  Here, among the many management blocks B included in the print management information portion PD, the first management block B1 corresponds to layout information indicating the areas of the color proofreading information portion CD and the print management information portion PD. For example, the layout information is expressed by a number indicating one of a plurality of patterns regarding the distribution of the color proofing information portion CD and the print management information portion PD. Therefore, management patches of colors and positions corresponding to the layout information numbers are arranged in the management block B1. Further, it is arranged at a predetermined position of the print management information part PD, and in the example of FIG. 2, it is arranged at the upper left of the print management information part PD.

  In order to generate patch sheet data representing the calibration patch sheet described above, the patch sheet data generation unit 20 includes a layout determination unit 21, a printer management unit 22, a management patch generation unit 23, and a calibration as shown in FIG. A patch generation unit 24;

  The layout determining unit 21 determines the layout of the color calibration information part CD and the print management information part PD of the calibration patch sheet. The printer management unit 22 manages print management information of the printer 2. Then, the management patch generation unit 23 generates a management patch associated with the print management information, and the calibration patch generation unit 24 generates a calibration patch, thereby generating patch sheet data as the patch sheet data generation unit 20.

  The print processing unit 30 is a part that causes the print engine 11 to perform printing in accordance with the patch sheet data generated by the patch sheet data generation unit 20. As illustrated in FIG. 4, the print processing unit 30 includes a drawing processing unit 31, a color conversion unit 32, a halftone processing unit 33, and an engine control unit 34.

  The drawing processing unit 31 receives the generated patch sheet data and converts it into RGB data which is bitmap data in RGB format. The color conversion unit 32 converts the RGB data into CMYK data corresponding to the color of the toner according to the color conversion table recorded in the ROM 14. The halftone processing unit 33 converts the CMYK data into print data corresponding to the presence / absence of dots formed by the print engine 11. The engine control unit 34 causes the print engine 11 to print a calibration patch sheet by transmitting the generated print data in a signal format corresponding to the print engine 11.

  Next, the color proofing unit 40 will be described. FIG. 5 is a diagram showing the configuration of the color proofing unit 40. As shown in FIG. 5, the color calibration unit 40 includes an image data acquisition unit 41, an image data correction unit 42, a layout analysis unit 43, a patch information acquisition unit 44, a print management information acquisition unit 45, a color calibration information acquisition unit 46, and A color calibration execution unit 47 is provided.

  Each component of the color proofing unit 40 shown in FIG. 5 is processed by the CPU 13 of the printer 2 by reading and executing a calibration program stored in the ROM 14. This calibration program may be stored in the ROM 14 in advance, or a program supplied from a recording medium such as a memory card and read from the recording medium may be stored in the ROM 14.

  The image data acquisition unit 41 reads out image data captured by the digital camera 3 from the memory card 4 set in the external memory I / F 16 and stores the image data in the RAM 15.

  Here, a method of photographing the calibration patch sheet by the digital camera 3 will be described. First, when a calibration patch sheet is photographed, a reference patch sheet having a calibration reference patch and a printed calibration patch sheet are superimposed and photographed at a time. FIG. 6 is a diagram illustrating an example of a reference patch sheet used for photographing. As shown in FIG. 6, the reference patch sheet has a print management information portion KPD, a color calibration information portion KCD, and an opening window W.

  The opening window W is in a state where a hole is opened at a position corresponding to the area of the print management information portion PD and the color proofreading information portion CD arranged in the center portion of the calibration patch sheet. Therefore, when the reference patch sheet is superimposed on the calibration patch sheet, the print management information portion PD and the color calibration information portion CD of the calibration patch sheet appear through the opening window W.

  In the color calibration information portion KCD of the reference patch sheet, a large number of patches of a color serving as a reference for calibration are arranged so as to surround the opening window W.

  The print management information portion KPD of the reference patch sheet is a portion representing the print management information corresponding to the reference patch sheet, and the print management information is obtained by the management blocks KB1 to KBn arranged so as to surround the color calibration information portion KCD. Represents.

  The reference patch sheet is, for example, output by a printer serving as a reference for calibration and prepared in advance, and the color of the patch included in the reference patch sheet is correct and serves as a configuration reference.

  Specifically, the calibration patch sheet and the reference patch sheet are photographed as follows. First, when photographing the calibration patch sheet, the user superimposes the reference patch sheet shown in FIG. 6 on the printing surface side from the calibration patch sheet shown in FIG. 2 (see FIG. 7A). Then, the digital camera 3 takes a picture with the sheets stacked. At this time, the calibration patch sheet is also photographed through the opening window W at the same time as the reference patch sheet is photographed. Accordingly, as shown in the patch sheet image of FIG. 7B, the calibration patch sheet is printed through the opening window W of the reference patch sheet inside the print management information portion KPD and the color calibration information portion KCD of the reference patch sheet. A management information portion PD and a color calibration information portion CD are photographed. When shooting is performed, the digital camera 3 generates patch sheet image data representing a bitmap image in the RGB format and records it on the memory card 4.

  The image data acquisition unit 41 of the color proofing unit 40 acquires patch sheet image data by reading data from the memory card 4 attached to the external memory I / F 16 of the printer 2. However, data recorded in the memory card 4 attached to the digital camera 3 may be read out via a cable connected to the digital camera 3.

  The image data correction unit 42 searches the image area of the reference patch sheet and the calibration patch sheet for the patch sheet image data read by the image data acquisition unit 41, and corrects the shape of the image area (hereinafter referred to as frame correction). )I do.

  The layout analysis unit 43 analyzes the corrected patch sheet image data and specifies the areas of the color proofing information part CD and the print management information part PD. As described above, since the layout information is included in the management block B1 arranged at a predetermined position, the layout analysis unit 43 searches the management block B1 and analyzes the management patch arranged in the management block B1. By doing so, layout information is acquired. Based on the layout information, the area of the color proofing information part CD and the print management information part PD and the area of each management block B of the print management information part PD are specified.

  The patch information acquisition unit 44 reads and acquires the color / position of the patch for each area of the management block B specified by the layout analysis unit 43.

  The print management information acquisition unit 45 analyzes the color and position of the management patch included in the management block B for the management blocks B2 to Bn excluding the management block B1 arranged in the print management information portion PD, and print management information To get.

  When analyzing the color and position of the management patch, the color definition table CT shown in FIG. 8 and the position definition table PT shown in FIG. 9 are used. The color definition table CT shows the correspondence between the color of the management patch and the patch ID value, and the position definition table PT shows the correspondence between the position of the management patch in the management block B and the patch ID value. The print management information acquisition unit 45 acquires the patch ID value from the color / position of the patch according to the color definition table CT and the position definition table PT.

  Here, the patch ID value is a number corresponding to the print management information, and the correspondence relationship follows the patch ID table IDT shown in FIG. In the patch ID table IDT of FIG. 10, the correspondence between the patch ID value and the print management information is determined in advance. Also, the contents of the print management information are determined for each number of the management block B. In the patch ID table IDT of FIG. 10, the management block B2 is “product model number”, the management block B3 is “production number”, and the management block. B4 corresponds to “printing resolution”. Therefore, the print management information acquisition unit 45 acquires the print management information from the patch ID value for each management block B.

  Note that the color definition table CT, the position definition table PT, and the patch ID table IDT shown in FIGS. 8, 9, and 10 are examples, and are not limited thereto. Alternatively, the patch ID value may be obtained using only either the color definition table CT or the position definition table PT.

  A process for acquiring the print management information will be specifically described. For example, the management block B shown in FIG. 3 includes “K100%” at position (1,1), “C100%” at position (4,1), and “M100% at position (2,2). The position (4, 3) includes a total of four management patches such as “MY 100%”. First, when the patch ID value is obtained from the color of the management patch, the color definition table CT is used. As shown in FIG. 8, in the color definition table CT, the management patch “K100%” corresponds to the patch ID value “2”. Similarly, management patches having color values of “C100%”, “M100%”, and “MY100%” correspond to patch ID values “4”, “8”, and “64” in order. Assuming that the patch ID value of the management block is the sum of the patch ID values in the block, the patch ID value “78 (= 2 + 4 + 8 + 64)” is obtained from the color of the patch according to the color definition table CT.

  The patch ID value is also obtained from the position of the management patch. In the position definition table PT, patch ID values are determined corresponding to the positions of the 4 × 4 vertical and horizontal areas into which the management block B is divided. In the position definition table PT of FIG. 9, both rows and columns are odd or even. The patch ID value “1” is given to the management patch at the position. Therefore, for the four management patches included in the management block of FIG. 3, the patch ID value obtained from the position is “2 (= 1 + 0 + 1 + 0)”.

  As the patch ID value of the management block, the total patch ID value obtained from the color and position is set as the final patch ID value of the management block B. Therefore, the patch ID value of the management block B in FIG. 3 is “80 (= 78 + 2)”. The print management information can be obtained by referring to the patch ID table IDT from the patch ID value of the management block B and the number of the management block B.

  In addition, the layout analysis unit 43, the patch information acquisition unit 44, and the print management information acquisition unit 45 perform the same process on the color calibration information portion KCD and the print management information portion KPD of the reference patch sheet as in the calibration patch sheet.

  The management patch generation unit 23 of the patch sheet data generation unit 20 converts the print management information into a patch ID value according to the patch ID table IDT, and the corresponding color from the patch ID value according to the color definition table CT and the position definition table PT. -A location management patch has been generated.

  The color proofreading information acquisition unit 46 is a color that is a reference for color proof acquired from the patch of the color proofreading information portion KCD of the reference patch sheet, and the color of the patch to be calibrated acquired from the color proofreading information portion CD of the proofreading patch sheet. Are compared in a predetermined color space such as a Lab color space, and a correction amount is obtained to obtain color calibration information for calibrating the color output characteristics of the printer 2.

  The color calibration execution unit 47 performs processing for calibrating the color output characteristics of the printer 2 in accordance with the print management information and the color calibration information.

  Next, the operation performed by the calibration system 1 will be described according to the flowchart. Since the calibration system 1 performs color calibration using the printed calibration patch sheet after the printer 2 has printed the calibration patch sheet, the printer 2 will be described from the process of printing the calibration patch sheet.

  FIG. 11 is a flowchart showing a flow of processing for printing a calibration patch sheet. When the printing process is started, first, the patch sheet data generation unit 20 performs a process of generating image data of a calibration patch sheet for printing. Therefore, in step S100, the layout determining unit 21 determines the layout of the areas of the color calibration information portion CD and the print management information portion PD in the patch sheet. For example, a layout is determined from a plurality of predetermined layout candidates, and a number indicating the determined layout pattern is used as layout information.

  Next, in step S101, the management patch generation unit 23 converts the layout information into a patch ID value. For example, a number indicating a layout pattern is handled as a patch ID value of layout information.

  Next, in step S <b> 102, the printer management unit 22 acquires print management information such as “product model number”, “manufacturing number”, and “printing resolution” from each configuration of the printer 2 such as the ROM 14.

  Next, in step S103, the management patch generation unit 23 converts the acquired print management information into a patch ID value in accordance with the patch ID table IDT. For each item included in the print management information, the patch ID values of the management blocks B2 to Bn are set using the position definition table PT and the color definition table CT. However, as the patch ID value, a value according to the table may be recorded in the ROM 14 or the like and may have a value in advance.

  Next, in step S104, the management patch generation unit 23 generates a management patch included in the management block B from the set patch ID value according to the color definition table CT and the position definition table PT. This process is performed for each block of the management block B1 corresponding to the layout information and the management blocks B2 to Bn corresponding to the print management information.

  In step S105, the calibration patch generator 24 generates a calibration patch included in the color calibration information portion CD. The color, gradation, position, and the like of the calibration patch are not characteristic features of the present invention, so that a predetermined patch may be generated, or may be generated according to a user selection or the like.

  Next, in step S <b> 106, the patch sheet data generation unit 20 generates patch sheet data representing a calibration patch sheet in which the management block B and the calibration patch are arranged according to the determined layout, and delivers the patch sheet data to the drawing processing unit 31.

  Next, in step S107, the print processing unit 30 performs a process of printing according to the patch sheet data. Here, the drawing processing unit 31, the color conversion unit 32, and the halftone processing unit 33 perform processing to convert the calibration patch sheet data into print data, and the engine control unit 34 prints the print data in a predetermined signal format. By passing to 11, the calibration patch sheet is printed.

  In this way, a calibration patch sheet including the color calibration information portion CD and the print management information portion PD can be printed.

  Next, the user performs an operation of photographing the printed calibration patch sheet with the digital camera 3. Here, description will be made according to the flowchart shown in FIG. 12 on the assumption that the user takes a picture according to a message displayed on the display panel 12.

  First, in step S200, the controller 10 causes the display panel 12 to display a message to set the calibration patch sheet and the reference patch sheet in an overlapping manner. The user sets the calibration patch sheet and the reference patch sheet in accordance with the message.

  Next, in step S201, the controller 10 causes the display panel 12 to display a message indicating that the calibration patch sheet and the reference patch sheet are to be captured while the sheets are stacked, and the user operates the digital camera 3 in accordance with the message to capture the image. I do.

  Next, in step S202, the digital camera 3 records the patch sheet image data obtained by photographing the calibration patch sheet and the reference patch sheet at the same time on the memory card 4, and ends the process shown in FIG.

  Further, according to a message displayed on the display panel 12, the user sets the memory card 4 in the external memory I / F 16 of the printer 2, and then operates the operation panel (not shown) of the printer 2 to perform calibration. When an instruction to this effect is input, the CPU 13 of the printer 2 executes the control program stored in the ROM 14 and starts the calibration process shown in the flowchart of FIG.

  In the calibration process, first, in step S300, the image data acquisition unit 41 searches for an image file stored in the memory card 4 and determines whether there is an unprocessed image file. If there is an unprocessed file (Yes), one unprocessed file is selected and the process proceeds to step S301. If there is no unprocessed image file (No), the process is terminated.

  In step S301, the image data correction unit 42 reads the patch sheet image data included in the image file, and recognizes the image areas of the reference patch sheet and the calibration patch sheet. As described above, since the calibration patch sheet is photographed in the area of the opening window W in the central portion of the reference patch sheet, the image areas of the reference patch sheet and the calibration patch sheet are extracted by extracting the outline of the reference patch sheet. Can be recognized.

  If the background color of the calibration patch sheet is white, shoot a sheet that is larger than the calibration patch sheet and the reference patch sheet and that has a background color such as a black background so that it further overlaps the back of the calibration patch sheet. In this case, the image areas of the reference patch sheet and the calibration patch sheet can be easily recognized by detecting the boundary between the black area and the white area.

Next, in step S302, it is determined whether or not the shift of the image area is within a predetermined range. Therefore, the amount of deviation from the rectangular shape is calculated for the recognized shape of the image region. For example, when the digital camera 3 is tilted with respect to the patch sheet and photographed, as shown in FIG. 14A, A (x1, y1), B (x2, y2), C (x3, y3), D ( A non-rectangular region surrounded by four vertices of x4, y4) is recognized as an image region of the reference patch sheet and the calibration patch sheet. At this time, assuming that the horizontal direction in FIG. 14 is the x direction and the vertical direction is the y direction, the x direction deviation amount Sx1 of the left side AC of the image area, the x direction deviation amount Sx2 of the right side BD, the y direction deviation amount Sy1 of the lower side AB, the upper side The y-direction deviation amount Sy2 of CD is calculated by the following equation.
Sx1 = x3-x1 (1)
Sx2 = x4-x2 (2)
Sy1 = y1-y2 (3)
Sy2 = y3-y4 (4)

  For example, the calculated ratio between the deviation amounts Sx1 and Sx2 and the ratio between Sy1 and Sy2 are not within a predetermined range (for example, a range of “0.9 to 1.1 when 10% deviation is allowed). In the case (No), it is determined that the image cannot be properly calibrated using the patch sheet image data because the image is too distorted, and the process for the image file is terminated. Return. If it is within the predetermined range (Yes), the process proceeds to step S303.

  In step S303, the image data correction unit 42 performs frame correction on the image areas of the reference patch sheet and the calibration patch sheet. Frame correction is performed by enlarging the image area in the x and y directions with the center of the image area as the center. Therefore, in the frame correction, as shown in FIG. 14B, the center position M is calculated from the coordinates of the four vertices A, B, C, and D of the reference patch sheet. Then, in order to enlarge the calibration patch sheet in the y direction with the center position M as the center, among the four areas divided in the x direction and the y direction with respect to the center position M, the areas in the first quadrant and the second quadrant The y-coordinate is enlarged in the positive y-coordinate direction while changing the enlargement ratio for each line perpendicular to the x-direction so as to eliminate the shift amount Sy2 of the upper side CD of the y-coordinate and obtain a constant y-coordinate. Next, the third quadrant and fourth quadrant are expanded in the negative y direction so that the shift amount Sy1 of the lower side AB of the y coordinate is eliminated and a constant y coordinate is obtained. As a result, the shape of the reference patch sheet is not displaced in the y direction, and a parallelogram image region indicated by a solid line in FIG. 14B is obtained.

  Next, the calibration patch sheet is enlarged in the x direction. Therefore, the first quadrant and the fourth quadrant with respect to the center position M are expanded in the positive direction of x so that the shift amount Sx2 of the right side BD of the x coordinate is eliminated and the constant x coordinate is obtained. The second quadrant and third quadrant regions are enlarged in the negative x direction so as to eliminate the shift amount Sx1 of the left side AC of the y coordinate and to obtain a constant x coordinate. Thereby, there is no shift in the x and y directions on each side of the image area of the patch sheet, and the rectangular shape shown by the solid line in FIG.

  Further, frame correction is completed by reducing and converting the obtained rectangular image area in the x direction or the y direction in accordance with a predetermined aspect ratio of the reference patch sheet. By performing the frame correction, the image areas of the reference patch sheet and the calibration patch sheet have the same aspect ratio and shape as the reference patch sheet regardless of the tilt and orientation of the digital camera 3 at the time of shooting.

  After completing the frame correction, in step S304, the layout analysis unit 43 searches for and detects the management block KB1 of the reference patch sheet. As described above, the management block representing the layout information is arranged so as to be located at the upper left of the calibration patch sheet. Therefore, the management blocks KB at the four corners of the reference patch sheet are detected and compared in consideration of the orientation of the reference patch sheet at the time of shooting. Then, among the four management blocks KB, the management block B that can be set as a layout information candidate is determined and set as the management block KB1.

  However, the method for determining the management block is not limited to this. For example, a predetermined mark may be printed around the position where the management block of the patch sheet is arranged, or four management blocks B1 may be arranged at the four corners of the patch sheet.

  In the management block KB1 of the reference patch sheet, the layout analysis unit 43 acquires color values and position information for all patches included in the block, and obtains patch ID values according to the color definition table CT and the position definition table PT. . Then, the layout information of the reference patch sheet corresponding to the patch ID value is acquired.

  Next, in step S305, the layout analysis unit 43 searches for and detects the calibration patch sheet management block B1. Since the range of the calibration patch sheet photographed through the opening window W is determined from the layout information of the reference patch sheet, the management block B at the four corners of the calibration patch sheet is compared to detect the management block B1 of the calibration patch sheet. To do. For the calibration patch sheet management block B1, color values and position information for all patches included in the block are acquired, and patch ID values for the calibration patch sheet are acquired according to the color definition table CT and the position definition table PT. To do.

Note that when acquiring the color value for each patch, the color value is obtained without taking the color value in the peripheral part of the patch into consideration in order to avoid the effect of correcting the distortion of the patch by frame correction. That is, as shown in FIG. 15, when reading the color value of one patch, the central portion (the halftone dot region in FIG. 15) excluding the region of Sx on both sides in the horizontal direction and the region of Sy on both sides in the vertical direction. ), The color value of the patch is obtained by averaging the gradation values of the patch sheet image data (bitmap data). For Sx and Sy, for example, a value determined by the following equation is used.
Sx = (Sx1 + Sx2) × 1.5 / 2 (5)
Sy = (Sy1 + Sy2) × 1.5 / 2 (6)

  In step S306, the layout analysis unit 43 determines whether the patch ID value of the calibration patch sheet calculated in step S305 is a value that can be recognized as layout information. When the patch ID value corresponds to the number as the layout information (Yes), the process proceeds to step S307. If the number does not correspond to the number as the layout information (No), the process proceeds to step S317.

  In step S307, the patch information acquisition unit 44 acquires color values and position information from the reference patch sheet. Here, for the print management information portion KPD of the reference patch sheet, the color value and position information of the patch are obtained for each management block KB, and the color value of the patch is obtained for the color calibration information portion KCD.

  In step S308, the print management information acquisition unit 45 prints the color value / position information of the patch in the print management information portion KPD of the reference patch sheet according to the color definition table CT, the position definition table PT, and the patch ID table IDT. Conversion to management information is performed, and print management information of the reference patch sheet is acquired.

  Next, in step S309, the patch information acquisition unit 44 acquires color values and position information from the calibration patch sheet. Here, for the print management information portion PD of the calibration patch sheet, the color value and position information of the patch are obtained for each management block B, and the color value of the patch is obtained for the color calibration information portion CD.

  Next, in step S310, the print management information acquisition unit 45 converts the color value / position information of the patch in the print management information portion PD into print management information according to the color definition table CT, the position definition table PT, and the patch ID table IDT. The print management information of the calibration patch sheet is acquired.

  Next, in step S311, it is determined whether information necessary for calibration is sufficient. For example, the print management information of the number corresponding to the management blocks B2 to Bn is not obtained, or the color / position information of the patch for all the gradation and color conditions that should be in the color calibration information portion CD of the calibration patch sheet. If it is not obtained or there is not enough information necessary for calibration (No), it is determined that calibration is impossible, and the process proceeds to step S318 to perform error processing. If the information necessary for calibration is sufficient (Yes), the process proceeds to step S312.

  In step S312, it is determined whether the print management information of the reference patch sheet and the calibration patch sheet is compatible. Here, the reference patch sheet corresponds to the printing condition of the calibration patch sheet by referring to the information indicating the printing conditions such as “product model number” and “printing resolution” included in the print management information. Determine if there is. If not (No), the reference patch sheet does not correspond to the calibration using the calibration patch sheet, so the process using the image file is terminated and the process returns to step S300. When it corresponds (Yes), it progresses to step S313.

  In step S313, the color calibration information acquisition unit 46 compares the color value of the color calibration information portion CD of the calibration patch sheet with the color value of the color calibration information portion KCD of the reference patch sheet as a reference, thereby obtaining the color calibration information. To get.

  Next, in step S314, the color proofreading information acquisition unit 46 corrects the color proofreading information using the color value of the patch in the print management information portion PD. As a correction method, for example, the color value of the patch acquired from the management block B and the color value of the patch acquired from the color calibration information portion CD may be corrected to an average value. The in-plane error caused by the position may be corrected in accordance with the positional relationship between the position of the patch and the patch of the color calibration information portion CD.

  In step S315, the color calibration execution unit 47 applies color calibration information to the printer 2 to perform color calibration. Specifically, when the color correction table generated from the color calibration information is stored in the ROM 14 and the printer 2 performs printing under the printing conditions specified in step S312, the color-converted CMYK data is stored in the color correction table. The color output characteristics can be calibrated by performing further conversion using. However, the color conversion table itself may be corrected by applying the color correction information to the color conversion table, or the color correction information may be directly applied to the CMYK data.

  Next, in step S316, when an image file representing processing results such as color calibration information and print management information is generated and recorded in the memory card 4, the calibration processing is terminated.

  In step S306, when it is determined that the patch ID value of the management block B1 cannot be recognized as layout information and the process proceeds to step S317, it is determined whether the patch ID value of the management block B1 can be recognized as color calibration information. To do. If the patch ID value of the management block B1 can be recognized as color calibration information (Yes), the process proceeds to step S318 and error processing is performed. If it is determined that it cannot be recognized (No), the process returns to step S300 and the next image file is processed.

  If the process proceeds from step S311 or step S317 to step S318, the process could not be performed correctly, so an error process is performed and the process proceeds to step S316. At this time, in step S316, image data representing the result such as the content of the error is written in the memory card 4, and the process is terminated.

  Steps S200 to S202 are the image capturing process, step S303 is the correction process, steps S307 and S309 are the patch acquisition process, steps S308 and S310 are the print management information acquisition process, and steps S313 and S314 are the calibration information generation process. It corresponds to.

  Hereinafter, effects of the present embodiment will be described.

  (1) Since the calibration patch sheet and the reference patch sheet are overlapped and photographed at one time, it is not affected by variations in photographing. Therefore, the color output characteristics can be calibrated more accurately.

  (2) Since the color output characteristic of the printer 2 can be calibrated using the digital camera 3, it is convenient for the user.

  (3) In the frame correction, the image distortion due to the tilt at the time of shooting is corrected according to the shape (rectangular / aspect ratio) of the reference patch sheet, so that it can be appropriately calibrated even if the digital camera 3 is shooting. it can.

  (4) Since the calibration patch for color calibration and the management patch representing the print management information are printed on one calibration patch sheet, the correspondence between the color calibration information and the printer 2 to be calibrated may be incorrect. Disappear. Therefore, color calibration can be performed accurately.

  (5) Since the correspondence between the print management information of the reference patch sheet and the print management information of the calibration patch sheet is collated, the correspondence between the calibration patch sheet and the reference patch sheet is not erroneous. Therefore, color calibration can be performed accurately.

  (6) By using the color calibration information acquired from the management patch and adjusting the color calibration information acquired from the calibration patch of the color calibration information portion CD, calibration is performed using more patches. Therefore, calibration can be performed with high accuracy.

  (7) Since the management patch is located in the peripheral portion of the calibration patch sheet as compared with the color calibration information portion CD, the color output characteristics can be corrected by using the color calibration information acquired from the management patch. Errors can be suppressed.

  (8) As shown in FIG. 2, the print management information is acquired by reading a patch composed of a rectangular area of a certain size, so that even a device with low reading accuracy can realize processing. Can do.

  (9) Since print management information cannot be obtained from the calibration patch sheet unless the position definition table PT, color definition table CT, and patch ID table IDT are referred to, the print management information does not leak from the calibration patch sheet. . That is, confidentiality can be given to the print management information of the calibration patch sheet.

  (10) If an error has occurred in the processing and the calibration could not be performed, the processing result of the error content was recorded as image data in the memory card 4, so whether or not the user was able to perform color calibration. It is possible to easily check the processing results.

  The embodiment of the present invention has been described above. The present invention is not limited to these embodiments, and can be implemented in various forms without departing from the spirit of the present invention. Hereinafter, a modification will be described.

  (Variation 1) In the above embodiment, the opening window W is provided in the central portion of the reference patch sheet. The position of the opening window W of the reference patch sheet is not limited to this. For example, as shown to Fig.16 (a), in addition to the opening window W of a center part, you may have an opening window part in four corners of a reference | standard patch sheet. In this case, as shown in FIG. 16B, the management block B of the print management information part PD is included at positions corresponding to the opening windows at the four corners. Further, as shown in the reference patch sheet of FIG. 16C and the calibration patch sheet of FIG. 16D, in addition to the management block of the print management information part PD, the color calibration information part CD is also arranged at the four corners. The reference patch sheet may have an opening window at a position corresponding to the reference patch sheet. According to this, since the position of the color calibration information portion CD of the calibration patch sheet is dispersed, the in-plane error can be suppressed by using the patch at each position.

  (Modification 2) In addition to the frame correction, the image data correction unit 42 may further correct the brightness of the image using the ground color of the sheet itself. For example, when the ground color portion of the photographed patch sheet image data is dark despite being printed using a white ground color sheet, the image data is corrected to increase the brightness. Thereby, it is possible to calibrate more suitably while suppressing the influence at the time of photographing by the digital camera 3.

  (Modification 3) As an image pickup device, in addition to the digital camera 3 described in the embodiment, a mobile phone with a camera function, a digital video camera, or the like may be used.

  (Modification 4) In the above-described embodiment, the printer 2 performs processing as the color proofing unit 40. As a fourth modification, the processing as the color proofing unit 40 may be performed by the host computer of the printer 2. For example, as shown in FIG. 17, the host computer 100 includes a color proofing unit 40 and a printer control unit 101. The color proofing unit 40 reads the patch sheet image data from the memory card 4 of the digital camera 3 and generates color proofing information. The printer control unit 101 passes the generated color calibration information to the printer 2 via the cable or the memory card 4 and causes the printer 2 to perform color calibration.

  (Modification 5) When photographing using a mobile phone with a camera function as an image capturing device, the host server of the mobile phone can provide a service as the color proofing unit 40. For example, when the user transfers patch sheet image data captured by a mobile phone to the server, the server generates color calibration information from the patch sheet image data, and transfers processing result data such as color calibration information to the mobile phone. The cellular phone records the processing result data transferred from the server in the memory card 4. The printer 2 can read out color calibration information from the memory card 4 and perform calibration.

  (Modification 6) In the above-described embodiment, the example in which various functions are realized by the CPU 13 of the printer 2 executing the program has been described. As a sixth modification, a function realized by software may be realized by a hardware circuit such as an ASIC. Of course, a part of the functions may be given to the hardware circuit, and the functions that the hardware circuit does not have may be realized by software.

The figure which showed the hardware constitutions of the calibration system which concerns on this embodiment. The figure which showed the calibration patch sheet. The figure which showed the management block. The figure which showed the patch sheet data production | generation part and the printing process part. The figure which showed the structure of the color proofreading part. The figure which showed the reference | standard patch sheet. The figure explaining the imaging | photography method of a calibration patch sheet and a reference | standard patch sheet. (A) is the figure which showed the state which the calibration patch sheet | seat and the reference | standard patch sheet were piled up, (b) is the figure which showed the patch sheet image image | photographed in piles. The figure which showed an example of the color definition table. The figure which showed an example of the position definition table. The figure which showed the patch ID table. 5 is a flowchart showing processing operations in printing processing. The flowchart which showed the operation | movement of the process which image | photographs a calibration patch sheet. The flowchart which showed the operation | movement of the process in a calibration process. The figure explaining frame correction. (A) is the state before frame correction, (b) is the state corrected in the y direction, and (c) is the state corrected in the x direction. The figure which showed the range of the patch which acquires a color value. The figure explaining a 1st modification. The figure explaining the 4th modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Calibration system, 2 ... Printer, 3 ... Digital camera as image photographing means, 4 ... Memory card as recording medium, 10 ... Controller, 11 ... Print engine as printing means, 12 ... Display panel, 13 ... CPU, 14 ... ROM, 15 ... RAM, 16 ... external memory interface, 20 ... patch sheet data generation unit, 21 ... layout determination unit, 22 ... printer management unit, 23 ... management patch generation unit, 24 ... calibration patch generation unit, 30 ... Print processing unit 31... Drawing processing unit 32. Color conversion unit 33 33 Halftone processing unit 34 Engine control unit 40 Color calibration unit 41 Image data acquisition unit 42 Image data correction unit 43 ... Layout analysis unit, 44 ... Patch information acquisition unit as patch acquisition means, 45 ... Print management information acquisition unit, 46 ... Calibration information generation unit Color calibration information acquisition unit, 47 ... color calibration execution unit, 100 ... host computer, 101 ... printer control unit, B ... management block, CD ... color calibration information part of calibration patch sheet, KCD ... color of reference patch sheet Calibration information part, PD ... print management information part of calibration patch sheet, KPD ... print management information part of reference patch sheet, W ... open window, CT ... color definition table, PT ... position definition table.

Claims (9)

A calibration method for calibrating the color output characteristics of the printing means using a reference patch sheet containing a color patch as a reference for calibration and a calibration patch sheet containing a patch printed by the printing means,
An image capturing step of capturing the reference patch sheet and the calibration patch sheet at a time by an image capturing unit, and generating image data representing the reference patch sheet and the calibration patch sheet;
From the image data, a patch acquisition step of acquiring the color of the patch included in the reference patch sheet and the color of the patch included in the calibration patch sheet;
A calibration information generation step of generating calibration information for calibrating the color output characteristics of the printing means by comparing the color of the patch included in the reference patch sheet and the color of the patch included in the calibration patch sheet; A calibration method characterized by comprising: The calibration method according to claim 1,
The reference patch sheet has an opening window in a region corresponding to the patch of the calibration patch sheet,
In the image photographing step, the calibration is performed in a state where the reference patch sheet is superimposed on the calibration patch sheet. The calibration method according to claim 2,
The calibration patch sheet arranges patches of the same color at a plurality of positions,
In the calibration information generating step, calibration information is generated using a plurality of patches of the calibration patch sheet. A calibration method according to any one of claims 1 to 3,
In the calibration information generation step,
When the calibration patch sheet includes print management information related to printing conditions of the calibration patch sheet, and the reference patch sheet includes print management information related to printing conditions to be calibrated for the reference patch sheet,
Calibration information for generating the calibration condition is generated when the printing condition indicated by the printing management information of the calibration patch sheet corresponds to the printing condition indicated by the printing management information of the reference patch sheet. Method. A calibration method according to any one of claims 1 to 4, wherein
The calibration patch sheet has a patch in which at least one of a color and a position arranged on the calibration patch sheet is associated with the print management information,
A calibration method, further comprising a print management information acquisition step of acquiring print management information based on at least one of the color or position of the patch. A calibration method according to any one of claims 1 to 5,
A calibration method, further comprising a correcting step of correcting the shape of the image areas of the reference patch sheet and the calibration patch sheet from the image data. A calibration system that calibrates the color output characteristics of a printing unit on which a calibration patch sheet is printed, using a reference patch sheet that includes a color patch that serves as a calibration reference and a calibration patch sheet that includes a patch printed by the printing unit. There,
Image photographing means for photographing the reference patch sheet and the calibration patch sheet at a time, and generating image data representing the reference patch sheet and the calibration patch sheet;
Patch acquisition means for acquiring the color of the patch included in the reference patch sheet and the color of the patch included in the calibration patch sheet from the image data;
Calibration information generating means for generating calibration information for calibrating the color output characteristics of the printing means by comparing the color of the patch contained in the reference patch sheet and the color of the patch contained in the calibration patch sheet; A calibration system characterized by comprising. A calibration program for calibrating the color output characteristics of the printing unit using a reference patch sheet including a patch having a color as a reference for calibration and a calibration patch sheet including a patch printed by the printing unit. ,
On the computer,
An image data acquisition step of reading the image data from a recording medium on which image data obtained by capturing the reference patch sheet and the calibration patch sheet at once by an image capturing unit and storing the image data in a storage unit;
From the image data read from the storage unit, a patch acquisition step of acquiring the color of the patch included in the reference patch sheet and the color of the patch included in the calibration patch sheet;
Performing a calibration information generating step of generating calibration information for calibrating the color output characteristics of the printing means by comparing the color of the patch of the reference patch sheet and the color of the patch of the calibration patch sheet. A featured calibration program. A computer-readable recording medium on which the calibration program according to claim 8 is recorded.

Images