Calibration method for density in image forming apparatus

[0001] [Technical field to which the invention belongs] The present invention relates to a calibration method, an image processing method, a printing system and a printing apparatus, and more particularly to a calibration for making the characteristics of a print output in a printing apparatus such as a printer and a copying machine constant. [0002] [Conventional technology] In printing devices that print characters and images on print media such as paper, such as color printers and copiers, the characteristics of print output, such as gradation in print results, are generally affected by changes in the printing environment and changes over time in the device itself. It is known that it may change. [0003] The printing environment is, for example, the temperature and humidity of the atmosphere in which the device is placed. By changing these, the amount of toner adhering to the print medium changes in the electrophotographic method, and the amount of ink adhered to the print medium in the inkjet method. The discharge amount may change and the output characteristics may not be desired. Further, when printing is continuously performed for a relatively long time, the temperature of each part of the apparatus may change, which may change the output characteristics. Furthermore, the output characteristics may change depending on the remaining amount of toner and the like. [0004] In addition, the secular change depends on the frequency of use of the printing device, but as a result of use for a relatively long period of time, the characteristics of each part of the device, for example, the charging characteristics of the photosensitive drum, change, and as a result, the output characteristics change. is there. [0005] The changes in print output characteristics of the individual printing devices described above also lead to another problem when a plurality of printing devices are used via a network such as an information processing system. That is, the output characteristics may change due to the various factors described above, and as a result, the output characteristics may differ between the plurality of printing devices. In this case, as described above, not only the desired print characteristics cannot be obtained in each printer, but also the print result differs depending on the printer selected by the user for print output in the system. [0006] It is generally known to perform calibration as a solution to the above-mentioned problems related to print output characteristics. There are roughly two forms of execution of this calibration. One is to output a predetermined patch pattern from a printing device to be calibrated, read it with a scanner or the like, and create calibration data based on the reading result to perform calibration. The other is independently performed in the printing device. For example, a patch pattern is formed on the photosensitive drum at a predetermined timing in the device, and the density is read by a sensor provided near the drum to obtain the density. It creates calibration data based on the data. In the above two forms, the calibration data is specifically created to update the contents of, for example, a gamma correction table in image processing. [0007] As the former calibration form, the applicant proposes a calibration performed between the host computer and the color printer constituting the system. This intervenes the user's operation. Specifically, among a plurality of computers constituting the system, a patch pattern is printed out from a color printer based on an instruction from a server computer, and this patch pattern is output. It is read by a scanner, calibration data is created based on the scan data read by the server computer, and the created calibration data is downloaded to the color printer. Then, in the color printer, gamma correction is performed using, for example, a gamma correction table updated by the downloaded calibration data, and printing is performed based on the data. [0008] This makes it possible to reduce variations in print output characteristics among a plurality of printing devices. This, for example, eliminates the difference in the output density characteristics of each printing device and determines the output density characteristics common to a plurality of printing devices, and can be said to stabilize the absolute density. The calibration described above is referred to as soft calibration below. [0009] Further, as the latter calibration form, the applicant proposes the following form. [0010] In the printer engine of the printing apparatus, the engine characteristic information is acquired after first correcting the maximum output densities of each of the cyan (C), magenta (M), yellow (Y), and black (K) colors at a predetermined timing. Then, the printer controller creates calibration data based on the engine characteristic information passed from the printer engine. Then, the printer engine can print based on the print data corrected by using the calibration data updated by this creation. According to this calibration, in particular, it is possible to suppress changes in print output characteristics that may occur in a printer device in a relatively short period of time, that is, changes in output characteristics due to changes in temperature, humidity, and the like. .. [0011] This form of calibration eliminates, for example, changes in output density characteristics that occur in individual printing devices, and can be said to be relative density stabilization with respect to the absolute density stabilization described above. In the following, this calibration will also be referred to as device calibration. [0012] [Problems to be Solved by the Invention] By the way, the above-mentioned two types of calibration have a configuration in which each functions independently, and there are the following problems when they do not have a correlation with each other. For example, even if soft calibration is performed at a certain timing according to a user's instruction, device calibration occurs at a predetermined timing uniquely determined by the printing device. Therefore, this device calibration changes the output characteristics of the printer engine. As a result, the effect of soft calibration does not last. In this case, in particular, it becomes impossible to obtain a print result having a stable absolute density, and in order to obtain such a print result, the user needs to perform soft calibration frequently. [0013] Therefore, the configuration is such that the execution of the soft calibration is associated with the execution of the device calibration, data for correcting the result of the soft calibration is obtained along with the device calibration, and the result of the soft calibration is finely adjusted by this correction data. Can be considered. According to this configuration, in particular, it is possible to maintain the output characteristics related to the absolute density obtained by soft calibration, and it is also possible to eliminate the fluctuation of the relative density of the printing apparatus that occurs in a relatively short period of time. [0014] However, in the configuration in which the soft calibration and the device calibration are associated with each other, when different image processing conditions for performing each calibration, for example, a binarization or multi-value method, are used. , The above fine adjustment may not be performed accurately. For example, when the dither method is used as the binarization method, when executing soft calibration, a dot-concentrated dither pattern that emphasizes gradation is set, while device calibration is executed. When the printer engine outputs a patch based on patch data based on a dot-distributed dither pattern that emphasizes resolution, the patch pattern output for the same gradation value data in each calibration. The gradation characteristics obtained from the above may be different. In this case, it cannot be said that the calibration data obtained by soft calibration and the correction data of the calibration data obtained by device calibration are mutually compatible, and as a result, the output characteristics of the printing device can be accurately adjusted. The reflected calibration data cannot be obtained. [0015] As described above, the situation where the set image processing conditions such as the dither method are inconsistent between the soft calibration and the device calibration is brought about by, for example, the following configuration of the printing system. The printer driver of the host computer is configured so that the binarization method as an image processing condition can be set directly or indirectly according to the image to be printed by the user, such as by selecting the type of image to be printed. There is something that has been done. In such a configuration, when performing soft calibration, the patch is printed based on the patch data based on the image processing conditions set by this user, while in device calibration, for example, preset in the printer engine. The patch is output based on the image processing conditions that have been set. As a result, there may be cases where the image processing conditions are different from each other. [0016] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to reduce the load on the user regarding so-called soft calibration and device calibration, especially regarding execution timing, and to reduce the load on the user. It is an object of the present invention to provide a calibration method, an image processing method, a printing system, and a printing apparatus capable of performing highly accurate calibration in which image processing conditions are mutually matched. [0017] Another object of the present invention is that when performing halftone processing using different halftone patterns corresponding to the type of object to be printed, all the different halftone patterns are not calibrated. The purpose is to provide an image processing device that makes it possible to do so. [0018] [Means for solving problems] Therefore, in the present invention, in the calibration method, a plurality of data that can be used in data generation for print output from the printing apparatus.<u style="single">Techniques for binarization or n-valued (n is greater than 2)</u>Of<u style="single">The plurality of numbers</u>Less predetermined number<u style="single">Techniques for binarization or n-valued (n is greater than 2)</u>each<u style="single">More processed</u>A patch is printed out based on the patch data, and the predetermined number of patches are printed out.<u style="single">Techniques for binarization or n-valued (n is greater than 2)</u>For each<u style="single">Information on measuring the density reproduction of the gamma correction table for converting the reading result of the patch into the ideal reproduction characteristics and the printing device when the patch is printed.</u>Is acquired, and at a predetermined timing, in the printing apparatus, the predetermined number<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>Same as<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>each<u style="single">More processed</u>The output of the patch based on the patch data and the measurement of the patch are performed, and the predetermined number of patches are measured according to the measurement result.<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>Same as<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>For each<u style="single">Information on measuring the density reproduction of the printing apparatus at the predetermined timing</u>And the above-mentioned predetermined number<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>For each<u style="single">Information on measuring the density reproduction of the printing device when the patch is printed.</u>When<u style="single">Information on measuring the density reproduction of the printing apparatus at the predetermined timing</u>Correction data is created based on the above, and the predetermined number<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>For each, the correction data created above<u style="single">Gamma correction table</u>To adjust the above multiple<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>Of which<u style="single">Binarization or n-value processing (n is greater than 2)</u>Is set in<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>Depending on the plurality of<u style="single">From the method for binarization or n-value (n is greater than 2)</u>A small number of<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>The above corresponding to one of<u style="single">Adjusted gamma correction table</u>And selected<u style="single">Gamma correction table</u>Using<u style="single">Gamma correction for image signals</u>And the selected<u style="single">Gamma correction table</u>Corresponds to<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>Then, for the gamma-corrected image signal<u style="single">Binarization or n-value processing (n is greater than 2)</u>It is characterized by having a step to perform. [0021] [0021] Further, a plurality of printing devices for performing printing, which can be used in data generation for print output from the printing device.<u style="single">Techniques for binarization or n-valued (n is greater than 2)</u>Of<u style="single">The plurality of numbers</u>Less predetermined number<u style="single">Techniques for binarization or n-valued (n is greater than 2)</u>each<u style="single">More processed</u>A patch output means for printing out a patch based on patch data, and the predetermined number of patches.<u style="single">Techniques for binarization or n-valued (n is greater than 2)</u>For each<u style="single">Information on measuring the density reproduction of the gamma correction table for converting the reading result of the patch into the ideal reproduction characteristics and the printing device when the patch is printed.</u>In the printing apparatus at a predetermined timing with the first acquisition means for acquiring the<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>Same as<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>each<u style="single">More processed</u>Based on the patch output based on the patch data, the patch output measuring means for measuring the patch, and the measurement result, the predetermined number<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>Same as<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>For each<u style="single">Information on measuring the density reproduction of the printing apparatus at the predetermined timing</u>The second acquisition means for acquiring the above and the predetermined number<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>For each<u style="single">Information on measuring the density reproduction of the printing device when the patch is printed.</u>When<u style="single">Information on measuring the density reproduction of the printing apparatus at the predetermined timing</u>A correction data creation means for creating correction data based on the above, and the predetermined number of correction data.<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>For each, the correction data created above<u style="single">Gamma correction table</u>And the plurality of adjustment means for adjusting<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>Of which<u style="single">Binarization or n-value processing (n is greater than 2)</u>Is set in<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>Depending on the plurality of<u style="single">From the method for binarization or n-value (n is greater than 2)</u>A small number of<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>The above corresponding to one of<u style="single">Adjusted gamma correction table</u>And the selection means to select<u style="single">Gamma correction table</u>Using<u style="single">Gamma correction for image signals</u>And the above-selected correction means<u style="single">Gamma correction table</u>Corresponds to<u style="single">Techniques for binarization or n-value (n is greater than 2)</u>Then, for the gamma-corrected image signal<u style="single">Binarization or n-value processing (n is greater than 2)</u>It is characterized by having a means for performing the above. [0023] According to the above configuration, in the so-called device calibration performed in the printing device at a predetermined timing, the number of the plurality of image processing conditions that can be used in the data generation for print output in the so-called soft calibration. The patch is output based on the patch data under the same image processing conditions as when the patch is printed out under a smaller predetermined number of image processing conditions, and the patch is measured. The measurement result of this patch and the predetermined number of image processings are performed. The second print output characteristic information is acquired based on the patch data according to the same image processing conditions as each condition, and the first print output characteristic information obtained by the soft calibration for each of the predetermined number of image processing conditions. The correction data is created based on the above-mentioned second print output characteristic information and the above-mentioned first calibration information is corrected by the created correction data to acquire the second calibration information, and the image is also obtained. In the processing, the calibration corresponding to one of a predetermined number of image processing conditions less than the number of the plurality of image processing conditions according to the image processing conditions set in the image processing among the plurality of image processing conditions. Since the measurement information is selected and the print output characteristics are corrected for the data using the selected calibration information, the first calibration information acquired by soft calibration is used as the basis, and after the data is acquired. Can be adjusted by the correction data by device calibration executed at a predetermined timing in the printing device. At the same time, the patches output in both soft calibration and device calibration are obtained based on the patch data under the same image processing conditions, so that the reading or measurement of each is different from each other due to the difference in the image processing conditions. In addition, it is not necessary to create and store calibration information for all of the multiple image processing conditions that can be used in data generation for print output. [0024] Further, according to still another embodiment of the present invention, a typical pattern is calibrated from a plurality of halftone patterns, and a pattern other than the above typical pattern is selected from the representative patterns. Since the calibration results of patterns with similar output density characteristics are used, it is not necessary to calibrate all different halftone patterns corresponding to the objects. [0025] BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [0026] In the embodiment described below, a color laser beam printer (LBP) will be used as an example of a printer device constituting the system, but other types of printers such as a color inkjet printer, a copier, and the like will be described. Needless to say, the present invention can be similarly applied to the printer of the above. Further, the halftone pattern related to the dither method as an image processing condition will be described using four types as an example, but it will be clear from the following description that the present invention can be similarly implemented with a larger number of types. [0027] In this embodiment, the dither method as a method of binarization or n (n is larger than 2) as an image processing condition uses four types of dither methods such as dot-concentrated type and dot-distributed type, and is soft. The calibration and the device calibration are performed in association with each other, and the calibration data obtained by the calibration is obtained for two of the above four types of dither patterns, which are smaller than the approximate ones. That is, calibration data in which the dither methods used for outputting patches in soft calibration and device calibration match or are similar to each other is obtained for each of the above four types of dither patterns. In the following description, the above two types of dither patterns, which are distinguished from the above four types of dither patterns by approximation, are referred to as halftone pattern A and halftone pattern B, respectively. [0028] The outline of the calibration of the present embodiment is the first calibration table (calibration information) corresponding to the halftone pattern A and the halftone pattern B by the soft calibration by the server computer, that is, the first gamma correction table. And the second engine characteristic information corresponding to the halftone patterns A and B obtained by creating the first engine characteristic information of the printer and performing device calibration in the printer controller of the printer, and the halftone. Based on the first engine characteristic information corresponding to the patterns A and B, the calibration table correction data corresponding to each halftone pattern is created, and the calibration table correction data and the above first calibration table are used. Use to create a second calibration table for each halftone pattern. Then, in the image processing using the second calibration table corresponding to the two types of halftone patterns A and B, it depends on whether the halftone pattern set at that time is the above four types of halftone patterns. Then, one of the above two types of halftone patterns is selected, and gamma correction is performed using the selected halftone pattern. Then, printing is performed by sending the data after the image processing to the printer engine. [0029] Hereinafter, the configuration of the print system of the present embodiment and the calibration based on the configuration will be specifically described. [0030] FIG. 1 is a block diagram showing a configuration of an information processing system or a print system according to an embodiment of the present invention. [0031] In FIG. 1, 1 indicates a server PC (personal computer) as an information processing device, and this server PC 1 is connected to network 5 and can execute various processes in the entire system including the calibration shown below. .. Therefore, software that realizes the above processing is installed on the server PC1. [0032] In the server PC1, reference numeral 11 denotes a calibration data storage unit configured in the server PC 1, and is used to hold the following calibration data. That is, 111 and 112 correspond to halftone pattern A among the two types of halftone patterns associated via the calibration table, as described later for the four types of halftone patterns that can be used in this system. The first engine characteristic A1 and the first calibration table A1, while 113 and 114 are the first engine characteristic B1 and the first calibration table B1 corresponding to the other halftone pattern B. These are stored in the calibration data storage unit 11. [0033] This system has a plurality of printers 2 (only one is shown in FIG. 1) as a printing device, and the printer 2 is connected to a network 5 to, for example, a plurality of client PCs 4 (similarly connected). Similarly, it is a device that can print by receiving data such as print data from (only one is shown), and can be the target of calibration described below. [0034] In the printer 2, reference numeral 21 denotes a calibration data storage unit, which is used to hold the following calibration data. That is, 211 and 212 are the first engine characteristic A1 and the first calibration table A1 corresponding to the halftone pattern A downloaded from the server PC1, and 213 and 214 are acquired from the printer engine as described later. The second engine characteristic A2, which is the latest engine characteristic, and the second calibration table A2, which is the latest calibration table, corresponding to the halftone pattern A, and these are stored in the calibration data storage unit 21. .. Similarly, in the calibration data storage unit 21, the first engine characteristic (B1) 215 and the first calibration table (B1) 216 corresponding to the halftone pattern B downloaded from the server PC1 and described later. The second engine characteristic (B2) 217, which is the latest engine characteristic, and the second calibration table (B2) 218, which is the latest calibration table, corresponding to the halftone pattern B obtained from the printer engine. Is stored. [0035] In addition, 22 indicates the printer controller of the printer 2, and controls various controls related to the printer 2 including the print process. As will be described later, this printer controller 22 is stored in the calibration data storage unit 21 when the first engine characteristics and the first calibration table corresponding to the two types of halftone patterns A and B are downloaded from the server PC1. It also stores and updates the second calibration table corresponding to the two types of halftone patterns in the calibration data storage unit 21 as described later. [0036] Further, 24 indicates a dither calibration compatible table that associates the halftone pattern with the calibration table, and by using this table, four types of image processing by the printer controller 22, which will be described later in FIG. 8, are performed. The calibration table corresponding to the halftone pattern A or B can be selected according to the set halftone pattern among the halftone patterns. [0037] Further, 23 indicates the printer engine of the printer 2, and is basically a part that prints based on the print data from the printer controller 22, but as will be described later, engine characteristics relating to the output density of the printer engine 23. It also executes a process of transmitting information to the printer controller 22 and adjusting the maximum density in the engine characteristics. [0038] The server PC1 of this system is used to connect the scanner 3 and measure the patch output by the printer 2 in calibration, but it is also used for the original purpose such as inputting a document. Further, the client PC 4 as an information processing device is connected to the network 5 to create and edit desired print data, instruct the printer 2 to print, and the like. [0039] In the calibration of the present embodiment in the print system or the information processing system described above, soft calibration is performed on the server PC1 as described above, and the calibration table (calibration information) for gamma correction created by this is printed on the printer. After downloading to 2, printer 2 basically performs gamma correction using this table and creates print data. Then, the printer 2 automatically performs device calibration at a predetermined unique timing, creates correction data of the downloaded calibration table, and fine-tunes the calibration table. Furthermore, in the calibration in which the above soft calibration and device calibration are associated, the halftone pattern A and the halftone pattern B, which are the dithering methods for binarization that can be used in this system, are described. Create the above calibration table and correction data. Further, in the image processing in the printer, four types of halftone patterns can be used, and the calibration table corresponding to these can be selected and used according to either halftone pattern A or B. [0040] In the following, first, with reference to FIGS. 2 to 8, soft calibration by the server PC 1, download of the created calibration data to the printer 2, and image processing using the calibration table in the printer 2 will be described. [0041] FIG. 2 is a flowchart showing a processing procedure of soft calibration and download of the data by the server PC1. Since this soft calibration is performed once and then adjusted by the device calibration in the printer 2, it is basically sufficient to perform this soft calibration once. However, the user may be able to instruct the execution of soft calibration when desired. This is to make it possible to deal with, for example, when the deterioration of the gradation becomes such that it cannot be corrected only by the adjustment by the device calibration. [0042] In FIG. 2, first, in step S20, the server PC1 instructs the printer 2 to output the patch data and print the patch. In response, the printer 2 prints the patch. [0043] FIG. 3 is a diagram showing this patch data in a printed state. In FIG. 3, 61 indicates the entire patch data, and 62 indicates one block constituting this patch data. That is, it shows the data corresponding to one patch. The numbers shown in each block indicate the data values of each patch, that is, the gradation values. This patch data consists of a total of 896 blocks of 32 x 28 in the vertical and horizontal directions, and the toner colors of the print in the horizontal direction are cyan (C), magenta (M), yellow (Y), and black (K). The blocks are arranged repeatedly in the order of, while in the vertical direction, blocks in which the gradation value is increased by 8 or 16 are arranged for each of the cyan, magenta, yellow, and black blocks. In detail, the patch data shown in the figure shows the patch data of the highlight part up to 128 with the gradation value increasing by 8 to 8 and the shadow part with the gradation value increasing by 16 from 140 to 255. Patch data is placed in 6 places. [0044] Here, the patch data shown in the figure includes patch data related to two types of halftone patterns. That is, in the vertical direction, patch data by halftone pattern A and halftone pattern B are alternately arranged, and these are binarized by halftone pattern A and halftone pattern B, respectively, when the patch is printed. .. Specifically, blocks 62 and 64 are halftone patterns A, blocks 63 and 65 are halftone patterns B, and so on. Of the patch data with the same gradation values in the vertical direction, the upper row is binary according to the gradation pattern A. It is the data to be binarized, and the lower row is the data to be binarized by the gradation pattern B. When the gradation values are 0 and 255, the same result can be obtained by binarizing with these halftone patterns, so only one block is arranged. [0045] The difference in the number of blocks between the highlight part and the shadow part in the patch data is that in this system, the highlight part requires more detailed gradation information than the shadow part. Further, the difference in the number of arrangements of the highlight portion and the shadow portion is because the variation of the input value in the scanner tends to be larger in the shadow portion than in the highlight portion. [0046] Further, the above patch data is transferred from the server PC 1 to the printer 2 and printed out from the printer 2 based on the above patch data. The patch data itself in the above format or information for configuring the data in the printer 2 is used. The patch may be printed based on the patch data owned above or the patch data composed of the constituent information according to the print instruction from the PC1. Alternatively, the patch data may be generated by transmitting the information for configuring the patch data from the server PC 1 to the printer 2. This patch data configuration information depends on the command system owned by the printer 2, but it is not mentioned here. [0047] In addition to printing the above-mentioned patch, in step S21, engine characteristic information is acquired from the printer 2 as the printer engine characteristics when the above-mentioned patch is printed. To acquire the engine characteristics, the second engine characteristics 211 and 215, which are the latest engine characteristics corresponding to the halftone patterns A and B stored in the calibration data storage unit 21 of the printer 2, are acquired, respectively. Do it by. The second engine characteristics 211 and 215 stored in the calibration data storage unit 21 may be obtained by executing device calibration as described later in FIG. 11 immediately after the patch print in step S20. Or it may be the latest engine characteristics obtained by the device calibration performed last. The command system related to data acquisition by the server PC1 is not mentioned here either. [0048] In step S21, the server PC1 further stores the second engine characteristics corresponding to the halftone patterns A and B acquired as described above as the first engine characteristics 111 and 113 in the calibration data storage unit 11. .. These first engine characteristics 111 and 113 are associated with the first caliber table obtained below as engine characteristics when a patch is printed. The details of determining the engine characteristics will be described later in FIG. [0049] Next, in step S22, the scanner 3 is used to read the printed patch. That is, when the user sets the paper on which the patch pattern is printed on the scanner 3 and performs a predetermined operation, the scanner 3 measures the density of each patch corresponding to the above-mentioned block of patch data, and the result is R. Output to server PC1 as G and B signals. From this input value, the server PC1 calculates the average of 4 points for the highlight part and the average of 6 places for the shadow part for each of the halftone patterns A and B based on the arrangement of the above patch data blocks, and the result is As a result, R, G, and B signal values are obtained for 24 gradation values for each of the C, M, Y, and K colors. Then, using a luminance density conversion table (not shown in FIG. 1) showing the correspondence between the R, G, B luminance signals of the scanner 3 and the C, M, Y, K luminance signals of the printer 2, the halftone pattern A, Obtain 24 concentration characteristic values from 24 luminance signals for each of B. Although not described in detail here, the scan of the scanner 3 is usually executed via the scanner driver configured on the server PC1, and the scan resolution is set and input via the scanner driver. The area is specified. [0050] Next, in step S23, the calibration table is created. [0051] FIGS. 4 (a) to 4 (c) are diagrams for explaining the principle. FIG. 4 (a) shows the patch of the printer 2 in which each gradation value of the patch data shown in FIG. 3 is input (in) and the density value of 24 steps obtained by the above-mentioned scanner 3 is represented as output (out). It is a figure which shows the output density characteristic at the time of printing. In the explanation using FIG. 4, for the sake of simplicity, only one color is illustrated and explained, but it goes without saying that the same processing is performed for the C, M, Y, and K4 colors. Further, in FIG. 4A, it is well known that the relationship between input and output is obtained by interpolation calculation from the above 24 values. [0052] A calibration table is created in order to obtain a linear relationship as shown in FIG. 4 (c) as an ideal characteristic of the concentration output characteristic with respect to the characteristic shown in FIG. 4 (a). Therefore, in order to bring the current output concentration characteristics (Fig. 4 (a)) closer to the ideal output concentration characteristics (Fig. 4 (c)), Fig. 4 (b) is the inverse function of the relationship shown in Fig. 4 (a). Obtain a calibration table having the relationship shown in. That is, when the printer 2 has the output density characteristic (FIG. 4 (a)), the printer is gamma-corrected by using the calibration table of the characteristic shown in FIG. 4 (b), specifically, the gamma correction table. As shown in FIG. 4 (c), the output density characteristic of 2 can be obtained so that the gradation value of the input density data becomes the gradation value of the print output as it is. [0053] In the above calibration table, two tables are created for the halftone pattern of the dither method, and the relationship between these halftone patterns and the output density characteristics will be described with reference to FIGS. 5 and 6. [0054] FIGS. 5 (a) and 5 (c) are diagrams showing the dot pattern of the patch printed out based on the binarized data having a gradation value of 128 by each dither method as an example. Of these, FIG. 5A is an example of a halftone pattern A, which is a dot-concentrated dither method that emphasizes gradation. In the case of such a pattern, since the gradation is generally high, it is often used for a photographic image, a gradation, or the like. Then, FIG. 5 (b) shows an example of the output density characteristic obtained by measuring the patch according to this halftone pattern A. On the other hand, Fig. 5 (c) is an example of halftone pattern B, which is a dot dispersion dither method that emphasizes resolution. In the case of such a pattern, since the resolution is generally high, it is often used for thin lines, characters, and the like. FIG. 5 (d) is a diagram showing an example of the output density characteristic of the halftone pattern B. [0055] On the other hand, FIG. 6 (a) shows a halftone pattern C similar to the halftone pattern shown in FIG. 5 (a). As a result, as shown in FIG. 6 (b), the output density characteristic also shows a characteristic close to that of the halftone pattern A shown in FIG. 5 (b). On the other hand, FIG. 6 (c) shows an example of a halftone pattern D similar to the halftone pattern B shown in FIG. 5 (c). In this case, as shown in FIG. 6 (d), the output density characteristic is similar to that of the halftone pattern B. [0056] As shown in these figures, the output density characteristics obtained from the patch differ depending on the difference in the halftone pattern which is the image processing condition. Therefore, it is desirable to perform the calibration according to each image processing condition. In the process of creating the above calibration table, FIG. 4 (b) has been described according to the output density characteristics (FIGS. 5 (b) and 5 (d)) obtained for each of the halftone patterns A and B. Create an inverse function like this as a calibration table. Then, as the calibration table corresponding to the other halftone patterns C and D, the calibration table corresponding to the approximate halftone pattern is selected and used as described later in FIG. [0057] When the calibration table is created in step S23, the calibration tables corresponding to the created halftone patterns are stored in the calibration data storage unit 11 as the first calibration tables 112 and 114, respectively. [0058] [0058] Next, in step S24, the first engine characteristic 111 and the first calibration table 112 corresponding to the halftone pattern A of the calibration data storage unit 11 and the first engine characteristic 113 corresponding to the halftone pattern B And download the first calibration table 114 to printer 2. The download command and the like at this time depend on the command system of the printer 2, but are not mentioned here. The first engine characteristic 111 and the first calibration table 112 corresponding to the downloaded halftone pattern A, the first engine characteristic 113 and the first calibration table 114 corresponding to the halftone pattern B are the printer controller. The calibration data storage unit 21 via 22 serves as the first engine characteristic 211 and the first calibration table 212 corresponding to the halftone pattern A, respectively, and the first engine characteristic corresponding to the halftone pattern B. Stored as 215 and the first calibration table 216. [0059] FIG. 7 is a flowchart showing a processing procedure of the printer controller 22 when the printer 2 receives download data from the server PC1 and the client PC4. This process is not limited to the above-mentioned download of calibration data, but indicates a process of receiving download data of various data such as print data. [0060] First, in step S70, data reception is awaited. If it is determined that data has been received in this process, the received data is analyzed in step S71. Then, the analysis result is determined in step S72, but if it is determined that the command is a calibration download command, it is determined in step S73 whether or not this data corresponds to the halftone pattern A. If it is related to the halftone pattern A, it is determined in step S74 whether or not the data is engine characteristics, and if it is engine characteristics, it is stored in the calibration data storage unit 21 in step S75 as described above. , The engine characteristic A1 is registered as the first engine characteristic 211 corresponding to the halftone pattern A. When it is determined in step S74 that it is not an engine characteristic, it is determined that it is a calibration table, and in step S76, as described above, the calibration data storage unit 21 is calibrated as a first caliber table 212 corresponding to the halftone pattern A. Register table A1. [0061] If it is determined in step S73 that the data does not correspond to the halftone pattern A, it is determined that the data corresponds to the halftone pattern B, and whether or not the data is an engine characteristic in step S77. When the determination is made and the engine characteristic is determined, the engine characteristic B1 is registered in the calibration data storage unit 21 as the first engine characteristic 215 corresponding to the halftone pattern B in step S78 as described above. When it is determined in step S77 that it is not an engine characteristic, it is determined that the table is a calib table, and in step S79, the calibration data storage unit 21 is provided with the calib table B1 as the first calib table 216 corresponding to the halftone pattern B. Register. [0062] If it is determined in step S72 that it is not a calibration download, the process corresponding to each command is performed in step S710. [0063] In this system, print data is passed from the application on the client PC4 and the server PC1 to the printer 2 via the respective printer drivers. On the other hand, the printer controller 22 of the printer 2 performs analysis of print data, composition of page layout, image processing, printing, and the like in step S710 of FIG. 7 described above. [0064] FIG. 8 is a flowchart showing the procedure of image processing by the printer controller 22 using the latest calibration table based on the downloaded calibration table described above and with the adjustments described later in FIG. 11 added to the table. is there. [0065] First, in step S110, color fine adjustment is performed on the input signals R, G, and B which are the print data sent from the client PC4 or the like as the host device. This color fine adjustment includes brightness correction and contrast correction. Next, the color matching process is performed in step S111. This color matching process is a process for matching the color of the monitor of the host device with the color of the print of the printer 2. Next, the luminance density conversion process is performed in step S112. This is a process of densifying the input signals, luminance R, G, and B, which are printer print signals, and converting them into C, M, Y, and K. [0066] Next, in step S118, the optimum calibration table is selected based on the halftone pattern set at that time. This selection process is performed using a table in which a halftone pattern that can be set in this system and a calibration table are associated with each other. [0067] FIG. 9 is a diagram schematically showing the contents of the dither calibration compatible table 24 (see FIG. 1) in which the halftone pattern is associated with the optimum calibration table. [0068] The contents of this table are determined according to the degree of approximation of the output density characteristics described with reference to FIGS. 5 and 6. [0069] That is, the halftone pattern A shown in FIG. 5 (a) and the halftone pattern C shown in FIG. 6 (a) are different halftone patterns, but as shown in FIGS. 5 (b) and 6 (b), respectively. , Their output density characteristics are similar. As shown in FIG. 9, the halftone pattern C having an output density characteristic close to that of the halftone pattern A is associated with the calibration table A based on the halftone pattern A. [0070] Similarly, the halftone pattern B shown in FIG. 5 (c) and the halftone pattern D shown in FIG. 6 (c) are different from each other, but are shown in FIGS. 5 (d) and 6 (d), respectively. As shown, the output density characteristics are similar. Therefore, as shown in FIG. 9, the halftone pattern D is associated with the calibration table B based on the halftone pattern B. [0071] An example of how to create the dither calibration compatible table 24 will be described. A plurality of gradation patches processed using the calibration tables A and B are printed out for the halftone patterns C and D. Then, the color of the printed gradation patch is measured. The calibration table whose result is closer to linear corresponds to the halftone pattern. [0072] In order to prevent the calibration accuracy from being lowered due to the difference in the halftone pattern used between the soft calibration and the device calibration, the above soft calibration and device calibration are performed for each of the halftone patterns that can be used in the system, and the calibration is performed. It is basically desirable to obtain a calibration table. However, in the present embodiment, as described above, all four types of halftone patterns are not calibrated as described above, but two less halftone patterns A and B are calibrated, and the resulting table A is obtained. , B is associated with other halftone patterns C and D. As a result, it is possible to reduce the deterioration of the performance of the system for creating the calibration table and the increase of the storage area required for storing the calibration table. [0073] In the above example, the method of selecting the optimum calibration table from the halftone patterns using the dither calibration compatible table was shown, but the table is not created and the halftone pattern is divided by conditional branching or the like. The above correspondence may be determined by the process of determining which calibration table to use. [0074] Next, the halftone pattern setting process will be described with reference to FIG. [0075] As shown in FIG. 10A, this process can be performed by the printer driver in the client PC 4 or the server PC 1 via a setting screen which is a user interface indicating a setting item called color halftone. As shown in the figure, the user can select one of (halftone) pattern A, pattern B, pattern C, and pattern D by operating the pull-down menu. FIG. 10 (b) shows another example of the user interface, in which the halftone pattern used for each object that makes up the page, such as images, graphics, and text, can be selected. [0076] After selecting the calibration table in step S118, in step S113, the halftone pattern corresponding to the selected calibration table is determined. [0077] Individually, the calibration table A is selected by the above-mentioned table correspondence in step S118, and therefore, when it is determined that the corresponding halftone pattern A is the halftone pattern A, in step S114, the determined halftone pattern A is selected. Gamma correction is performed using the calibration table A (2). That is, the second caliber table 214, which is the latest caliber table corresponding to the halftone pattern A, uses the 8-bit multi-valued signals of C, M, Y, and K obtained by the luminance density conversion in step S112 as input / output signals. Is used to perform gamma correction and linearly convert the input characteristics indicated by the multi-valued signal. Next, in step S115, the 8-bit signals of C, M, Y, and K are converted into binary signals according to the output system by using the dither method of the halftone pattern A. In the present embodiment, the binarization process of converting the signal into a signal of 1 bit each of C, M, Y, and K is performed in this way. Of course, it may be there. [0078] On the other hand, when it is determined in step S113 that the calibration table B corresponding to the halftone pattern B is selected, the second caliber table 218, which is the latest calibration table corresponding to the halftone pattern B, is used in step S116. Then, gamma correction is performed. Then, in step S117, the binarization process is performed using the halftone pattern B. [0079] As described above, the soft calibration mainly described with reference to FIG. 2 can eliminate the difference in the output density characteristics between the devices and stabilize the absolute density, but the engine characteristics of the printer can be determined in each device, for example. It changes relatively easily when the drum temperature rises or the ambient temperature changes due to continuous printing or the like. Therefore, the printer 2 can independently perform device calibration, correct the calibration table obtained by the above-mentioned soft calibration with the correction data obtained by the device calibration, and adjust the contents of the calibration table. As a result, the user does not need to perform soft calibration frequently, and the burden on the user can be reduced. Then, by performing the above-mentioned soft calibration and the device calibration described below for each of the plurality of halftone patterns that can be used in the system, it is possible to improve the accuracy of the calibration. [0080] [0080] In the following, the device calibration of the present embodiment and the process of obtaining the latest calibration table by the device calibration will be described mainly with reference to FIG. [0081] FIG. 11 is a flowchart showing a processing procedure of device calibration mainly in the printer 2. [0082] This device calibration is performed on engine characteristics such as temperature and humidity changes detected by temperature and humidity sensors (not shown) installed in the printer engine 23, changes in drum temperature, number of prints, and replacement of drums and toner cartridges. Is triggered by an event that is likely to change. Other events that trigger this can be considered, but the details are not mentioned here. [0083] In this process, first, in step S31, the maximum densities of the C, M, Y, and K colors in the printer engine 23 are adjusted. Normally, a printer engine has a target maximum density at the time of design, but the density fluctuates due to aging and the like. In this step, a patch is formed on a development system (not shown), for example, on a drum with maximum density data and some other gradation value data (other than the maximum density value is used in the processing of the next step S32) for each color. Is developed with each color toner, and the maximum density value of each color of C, M, Y, and K at that time is obtained by measuring them with a sensor. Then, when this maximum value changes from the target value, the development bias value and the like are controlled to make adjustments to obtain an appropriate maximum density. The patches formed above are formed for each of the halftone patterns A and B, similar to those shown in FIG. [0084] FIG. 12 is a diagram showing the output density characteristics at this time, and the maximum density adjustment will be described in more detail with reference to this diagram. The characteristic curve 2 shown in the figure is an example showing the concentration characteristic curve before the maximum concentration adjustment, and the characteristic curve 1 is an example of the concentration characteristic curve after the maximum concentration adjustment. The maximum concentration of the characteristic curve 2 shows max2. In the maximum concentration adjustment process in step S31, the sensor on the drum detects that the maximum concentration value at that time is max2. On the other hand, since the target value of the maximum density is max1, the printer engine 23 controls the development bias value and the like, and adjusts so that the maximum density becomes max1. [0085] After the above maximum concentration adjustment, in step S32, the latest engine characteristic, engine characteristic 2, is acquired. This process is performed by returning several intermediate density sensor values from the printer engine 23 to the printer controller 22 in response to the request from the printer controller 22. That is, as described above, the concentration of some patches other than the maximum density value formed on the drum at the time of the maximum density adjustment is measured by the sensor, and the measured value is sent to the printer controller 22. Then, this measured value is stored as the latest engine characteristic 2 in the calibration data storage unit 21 as the engine characteristic A2 (or B2). [0086] This situation will be described with reference to FIG. In FIG. 12, for the sake of simplicity, the intermediate input gradation values of four points and the measured values of the corresponding sensors are shown, but it goes without saying that these points are not limited to this. Further, although one halftone pattern, for example, halftone pattern A is described as an example, the same applies to other halftone patterns B. [0087] In FIG. 12, A, B, C, and D on the horizontal axis are predetermined input gradation values, and a, b, c, and d on the vertical axis are patches formed by each input gradation value. It is a concentration value measured by a sensor. The printer engine 23 passes the four measured values a, b, c, and d to the printer controller 22. [0088] The values measured by the sensor before the maximum concentration adjustment are a', b', c', and d', and change to a, b, c, and d by the above maximum concentration adjustment. That is, since the measured value of the sensor, that is, the engine characteristic is greatly affected by the maximum concentration adjustment, it is necessary to always perform the processing in the order of the maximum concentration adjustment and the engine characteristic acquisition as a series of flows. [0089] In general, the development type sensor does not have the accuracy to surely obtain an absolute density value because the characteristics of the sensor itself vary. However, if the same sensor is used, even if the characteristics of the developing system change, it is possible to obtain a measured value according to the change. That is, although the absolute accuracy is low, the accuracy of detecting relative changes can be expected. [0090] Next, in step S33, it is determined whether or not the calibration tables 1 (A1 and B1) have been downloaded to the calibration data storage unit 21. If the calibration table 1 has not been downloaded, the calibration tables 2 (A2 and B2) are created in step S34 in the same manner as the conventional device calibration. That is, in this case, the soft calibration described in FIG. 2 has not yet been performed. In that case, a calibration table should be created using the measured values by the sensor and used for the subsequent printing process. To. [0091] Explaining this process using the characteristic curve 1 shown in FIG. 12, first, the characteristic curve 1 is obtained from the measured values a, b, c, and d of the sensor, which are engine characteristics, by an approximate expression, and as described above using FIG. To calibration table 2 can be created by finding the inverse function to obtain the target characteristics. [0092] On the other hand, when it is determined in step S33 that the calibration table 1 has been downloaded, the calibration table correction data corresponding to each halftone pattern is created in step S35. [0093] The correction data is created as follows. Here, one halftone pattern A is described as an example, but the same processing is performed for the halftone pattern B as well. First, from the second engine characteristic data 213 of the calibration data storage unit 21, which is the latest engine characteristic and acquired in step S32, a characteristic curve such as the characteristic curve 1 shown in FIG. 12 is obtained by an approximate expression. Next, the characteristic curve is similarly obtained from the first engine characteristic 211, which is the engine characteristic at the time of soft calibration, by an approximate expression. Then, for each engine characteristic, as described above in FIG. 4 as provisional calibration data, a provisional calibration table is obtained by obtaining an inverse function curve in order to obtain the linearity shown in FIG. 4 (c) as a result. obtain. Calibration correction data is created by taking the difference between these two temporary calibration tables. This correction data is information indicating changes in characteristics such as the engine and its sensor level. [0094] Next, in step S36, the calibration tables 2 (A2 and B2) corresponding to each halftone pattern stored in the calibration data storage unit 21 are updated. This process is performed by merging the calibration table correction data created in step S35 and the calibration tables 1 (A1 and B1) stored in the calibration data storage unit 21. That is, this calibration table 1 is obtained and downloaded by the soft calibration by the server PC1 described above in FIG. 2, and the contents are adjusted by merging with the above correction data. [0095] In the next step S37, the calibration table 2 updated as described above according to each halftone pattern is stored in the calibration data storage unit 21. [0096] FIG. 13 is a diagram illustrating a series of these processes. Here, one halftone pattern will be described, but the same processing will be performed for the other halftone pattern. FIG. 13A shows a first calibration table 1 generated by soft calibration, downloaded, and stored in the calibration data storage unit 21 of the printer 2. The maximum densities of each of the C, M, Y, and K colors in the printer engine 23 as shown in FIG. 13 (b) are adjusted, and the engine characteristic 2 is acquired. Then, the calibration correction data, which is the difference between the engine characteristic 2 and the engine characteristic 1 at the time of soft calibration, as shown in FIG. 13 (c), is created, and the compensatory data is merged with the caliber table 1. Is done. Then, the latest caliber table 2 created is stored in the calibration data storage unit 21 as the second caliber table 214. [0097] In this way, the printer controller 22 of the printer 2 uses the second caliber table, which is the latest calibration table according to the halftone pattern stored in the calibration data storage unit 21, to perform the image processing shown in FIG. It can be performed. [0098] Although the device calibration described above is automatically performed in the printer, it can be similarly performed not only in the electrophotographic method of the present embodiment but also in other printing type printers. For example, in the case of an inkjet printer, an optical sensor may be provided on a carriage for scanning by mounting a recording head, and the density may be detected by scanning the recording head and scanning the recorded patch in the same manner. it can. [0099] 14 and 15 are views for explaining the calibration process described with reference to FIGS. 2 to 13 from the aspect of the user interface (UI) of the server PC1. That is, the calibration of this embodiment is configured on the server PC1 as a kind of application. [0100] When this application is started in step S80 of FIG. 14, it is first determined whether or not the printer driver and scanner driver required in step S81 are installed in the system of PC1. If the required driver is not installed, a driver check error is displayed in step S814, and the process ends in step S813. When it is determined in step S81 that the necessary driver is installed, the main screen is displayed in step S82. [0101] An example of this main screen is shown in FIG. Other screens basically have "Next", "Back", "Cancel", and "Help" buttons as shown in Fig. 15, and you can move to other related screens by pressing them. On the main screen of FIG. 14, three types of selection menus are set: "new", "open existing measurement data", and "delete download data". If "New" is selected here and "Next" is clicked, the process proceeds to step S84. In step S84, the patch data is output to the printer 2. Next, in step S87, as described above, the scanner 3 measures the density of the printed patch. [0102] Next, in step S88, calibration is applied. In this step, the processes of steps S23 and S24 in FIG. 2 described above, that is, calibration data is created and the data is downloaded to the printer 2. In step S88, a button for transitioning to steps S89 and S810 is prepared, and the transition can be performed by pressing the button by the user. Step S89 is a screen that enables saving of the measurement data, and saves the scan data measured in step S87. This saved file can be used in processing using existing measurement data, which will be described later. Step S810 is a screen for displaying detailed information, and displays detailed information such as displaying the measured concentration characteristics. After exiting steps S89 and S810, the process returns to step S88. [0103] In step S811, the processing end screen is displayed. If you specify the end of the application on this screen, the process ends in step S813, and if you specify to return to the main screen, the process returns to step S82. [0104] When "Open measurement data" is selected on the main screen of step S82 and "Next" is clicked, the screen for instructing the measurement data in step S85 is displayed. Here, by pressing the "reference" button, the screen shifts to the measurement data reading screen in step S812. Here, it is possible to search the measurement data in detail. Further, this measurement data is a data file saved in step S89 described above. Next, calibration is applied in step S88. The rest is the same as above. [0105] When "Delete downloaded data" is selected on the main screen of step S82 and "Next" is clicked, the calibration data stored in the calibration data storage unit 21 of the printer 2 is deleted in step S86. This is done by instructing the printer 2 from the server PC1 by a command, but the command is not mentioned. Next, the screen moves to the end screen S811. The rest is the same as described above. [0106] &lt;Other embodiments&gt; As described above, the present invention is applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.) but also applied to a device composed of one device (for example, a copier, a facsimile machine). You may. [0107] Further, as shown in FIGS. 2, 7, 8 and 11, a device or a computer in the system connected to the various devices so as to operate the various devices so as to realize the functions of the above-described embodiment. The present invention also comprises supplying a program code of software for realizing the above-described embodiment and operating the various devices according to a stored program in a computer (CPU or MPU) of the system or device. Included in the category. [0108] Further, in this case, the program code itself of the software realizes the function of the above-described embodiment, and the program code itself and a means for supplying the program code to the computer, for example, a storage storing the program code. The medium constitutes the present invention. [0109] As a storage medium for storing such a program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a non-volatile memory card, a ROM, or the like can be used. [0110] Further, by executing the program code supplied by the computer, not only the functions of the above-described embodiments are realized, but also the OS (operating system) in which the program code is running in the computer, other application software, etc. Needless to say, such a program code is included in the embodiment of the present invention even when the function of the above-described embodiment is realized in collaboration with the above-mentioned embodiment. [0111] Furthermore, the supplied program code is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, and then the CPU provided in the function expansion board or the function expansion unit is provided based on the instruction of the program code. It goes without saying that the present invention also includes a case where a part or all of the actual processing is performed by the processing, and the function of the above-described embodiment is realized by the processing. [0112] [Effect of the invention] As described above, according to the present invention, in the so-called device calibration performed in the printing device at a predetermined timing, a plurality of image processing conditions that can be used in data generation for print output at the time of so-called soft calibration are used. Among them, the patch is output based on the patch data under the same image processing conditions as when the patch is printed out under the predetermined number of image processing conditions smaller than the number, and the patch is measured, and the measurement result of this patch and the above-mentioned predetermined number are performed. The second print output characteristic information is acquired based on the patch data according to each of the number of image processing conditions and the same image processing conditions, and the first soft calibration is obtained for each of the predetermined number of image processing conditions. Correction data is created based on the print output characteristic information and the second print output characteristic information, and the created correction data is used to correct the first calibration information described above and acquire the second calibration information. Further, in the image processing, one of a predetermined number of image processing conditions smaller than the number of the plurality of image processing conditions according to the image processing conditions set in the image processing among the plurality of image processing conditions. Since the calibration information corresponding to the above is selected and the print output characteristics are corrected for the data using the selected calibration information, the first calibration information acquired by the soft calibration is used as the basis, and it is based on the first calibration information. After being acquired, it can be adjusted by the correction data by the device calibration executed at a predetermined timing in the printing device. At the same time, the patches output in both soft calibration and device calibration are obtained based on the patch data under the same image processing conditions, so that the reading or measurement of each is different from each other due to the difference in the image processing conditions. In addition, calibration information is created and stored for all of the multiple image processing conditions that can be used in data generation for print output. [0113] As a result, the load on the user regarding the execution timing of soft calibration and device calibration is reduced, and the storage area for these calibrations is minimized without causing a decrease in system performance. It is possible to perform high-precision calibration in which the image processing conditions are mutually matched while suppressing the calibration. [0114] According to still another embodiment of the present invention, a typical pattern is calibrated from a plurality of halftone patterns, and for patterns other than the above typical patterns, the output density of the typical patterns is obtained. Since the calibration results of patterns with similar characteristics are used, it is not necessary to calibrate all different halftone patterns corresponding to the objects. [Simple explanation of drawings] FIG. 1 is a block diagram showing a configuration of a print system according to an embodiment of the present invention. FIG. 2 is a flowchart showing a processing procedure of soft calibration constituting the calibration according to the embodiment of the present invention. FIG. 3 is a diagram showing patch data printed out by the above soft calibration. 4 (a) to 4 (c) are diagrams for explaining a process of creating a calibration table based on an output density characteristic obtained from a patch density measurement result. 5 (a) to 5 (d) are diagrams for explaining that the output density characteristics differ depending on the type of halftone pattern which is an image processing condition. 6 (a) to 6 (d) are diagrams for explaining that the output density characteristics differ depending on the type of halftone pattern, which is also an image processing condition. FIG. 7 is a flowchart showing a process of receiving data from a server PC in the printer according to the embodiment of the present invention and processing of calibration data among the received data. FIG. 8 is a flowchart showing image processing in the above printer, particularly using a calibration table. FIG. 9 is a schematic diagram showing a table showing the correspondence between the halftone pattern and the optimum calibration table used in the above image processing. 10 (a) and 10 (b) are diagrams for explaining two examples of setting a halftone pattern, that is, a dither pattern used in the above image processing. FIG. 11 is a flowchart showing a processing procedure of device calibration constituting the calibration according to the embodiment of the present invention. FIG. 12 is a diagram showing an output density characteristic for explaining the adjustment of the output density characteristic of the printer engine by the device calibration. 13A to 13D are diagrams for explaining adjustment of the calibration table obtained by soft calibration using the calibration table correction data obtained by the above device calibration. FIG. 14 is a diagram illustrating calibration according to an embodiment of the present invention from the aspect of a user interface. FIG. 15 is a diagram showing an example of a display screen of the user interface. [Explanation of symbols] 1 server PC 2 printer 3 scanner 4 Client PC 5 network 11 Calibration data storage 21 Calibration data storage 22 Printer controller 23 printer engine 24 dither calibration compatible table