JP6944290B2 - Image processing device - Google Patents

Description

The present invention relates to an image processing device, an image forming device and a program.

An electrophotographic printer engine forms an electrostatic latent image on a photoconductor based on image data, and develops the electrostatic latent image using a developer in a developing device to form an image. Since the image density changes depending on the state of the printer engine, gradation correction is required. Gradation correction is a calibration for maintaining the density of an image at a predetermined density. According to Patent Document 1, it is described that a measurement image formed on a sheet is read by a scanner (in-line sensor) provided in an image forming apparatus to perform gradation correction (first calibration).

By the way, the gradation characteristics of an image differ depending on the type of sheet (presence or absence of coating, basis weight, etc.). According to Patent Document 1, it is described that a print server executes calibration for each type of sheet to create a gradation correction table for each type of sheet (second calibration). In particular, the measurement image formed on the sheet by the image forming apparatus is read by an external scanner connected to the print server.

Japanese Unexamined Patent Publication No. 2014-113810

In the second calibration, a target gradation characteristic (target gradation) is determined in advance for each type of sheet, and a gradation correction table is created so that the target gradation is maintained. The operator often desires to use a familiar commercially available colorimeter (eg, i1Pro2 manufactured by X-Rite) to determine the target gradation. On the other hand, in the second calibration, a colorimeter may be used or an in-line sensor may be used.

If the in-line sensor provided in the image forming apparatus can measure the test chart in the second calibration, the operator does not need to manually measure the test chart. However, some operators want to perform a second calibration using the measurement results of the test chart by the colorimeter. In this case, a conversion table that converts the measurement result of the in-line sensor into the measurement result of the colorimeter is required. In order to create the conversion table, a test chart for the inline sensor and a test chart for the colorimeter are required separately. This is because the measurement rules of the in-line sensor (size and spacing of test images, etc.) and the measurement rules of the colorimeter are different. Therefore, the present invention provides an image processing device capable of reducing the number of sheets on which a measurement image is formed.

The present invention is, for example,
An image processing device that causes an image forming device to form a plurality of test images read by the first measuring device and the second measuring device on the same sheet.
A first layout rule that defines the layout of the plurality of test images so that the first measuring instrument can measure the plurality of test images, and the second measuring instrument can measure the plurality of test images. A storage means for storing the second layout rule that defines the layout of the plurality of test images, and
A transmission means for transmitting image data having the plurality of test images arranged on the sheet so as to satisfy both the first layout rule and the second layout rule to the image forming apparatus .
Based on the measurement results of the plurality of test images by the first measuring instrument and the measurement results of the plurality of test images by the second measuring instrument, the measurement results by the first measuring instrument are used as the measurement results of the second measuring instrument. Provided is an image processing apparatus having a production means for creating a conversion condition to be converted.

According to the present invention, there is provided an image processing apparatus capable of reducing the number of sheets on which a measurement image is formed.

Schematic cross-sectional view of the image forming apparatus Diagram showing an in-line sensor The figure explaining the function related to image processing in an image forming apparatus. The figure explaining the image processing apparatus Diagram explaining the test chart Diagram illustrating an improved test chart The figure which shows the measurement result Flowchart showing how to create a concentration conversion table The figure which shows the image formation system including DFE Table showing layout rules Diagram showing the test chart Diagram showing the test chart Flowchart showing how to create a common test chart Diagram showing the user interface Diagram showing a common test chart Flowchart showing how to create a common test chart The figure explaining the function realized by a CPU

[Example 1]
<Image forming device>
In FIG. 1, the image forming apparatus 100 includes a printing unit 101, a reader unit 400, and an operating unit 180. The print unit 101 is a printer engine having four stations 120, 121, 122, and 123 that form an image for each color component. The station 120 is an image forming unit that forms a yellow image. The station 121 is an image forming unit that forms an image of magenta. The station 122 is an image forming unit that forms an image of cyan. The station 123 is an image forming unit that forms a black image. Since the configuration of each station is the same, the configuration of the station 120 forming the yellow image will be described below.

The photosensitive drum 105 is a photoconductor having a photosensitive layer. The photosensitive drum 105 functions as an image carrier that supports an electrostatic latent image or a toner image. The charger 111 charges the photosensitive drum 105 so that the potential on the surface of the photosensitive drum 105 becomes a predetermined potential (charging potential). The exposure apparatus 103 forms an electrostatic latent image on the surface of the photosensitive drum 105 by irradiating the photosensitive drum 105 with a laser beam controlled based on the image data. The developing device 112 has an accommodating portion for accommodating a developer containing toner and a magnetic carrier, and a developing sleeve 12 provided in the accommodating portion for carrying the developing agent and rotating. The developer 112 develops an electrostatic latent image using a developer to form a toner image. The primary transfer roller 118 transfers the toner image on the photosensitive drum 105 to the intermediate transfer belt 106. The intermediate transfer belt 106 functions as an image carrier that carries the toner images formed by the stations 120, 121, 122 and 123. The intermediate transfer belt 106 rotates to transfer the toner image to the secondary transfer roller 114. Various transport rollers such as the secondary transfer roller 114 are examples of transport means for transporting the sheet along the transport path.

A density sensor 117 for measuring the density of the measurement image (test image) formed on the intermediate transfer belt 106 is arranged around the intermediate transfer belt 106. The density sensor 117 is, for example, an optical sensor. The density sensor 117 outputs a signal according to the amount of toner adhering to the measurement image formed on the intermediate transfer belt 106. That is, the density sensor 117 detects the density of the measurement image formed on the intermediate transfer belt 106. The image forming apparatus 100 controls the image forming conditions so that the density of the image formed by the stations 120, 121, 122 and 123 becomes the target density based on the measurement result of the density sensor 117. Here, the image forming condition is the intensity of the laser of the exposure apparatus 103 and the like.

The paper feed unit 113 feeds the sheet 110 so that the timing at which the toner image carried on the intermediate transfer belt 106 arrives at the secondary transfer roller 114 coincides with the timing at which the sheet 110 arrives at the secondary transfer roller 114. And transport. The secondary transfer roller 114 transfers the toner image supported on the intermediate transfer belt 106 to the sheet 110. A transfer voltage is applied to the secondary transfer roller 114. The sheet 110 to which the toner image is transferred is conveyed to the fixing device 150.

The fuser 150 includes a fixing roller 151 having a heater for heating the sheet 110, and a pressure belt 152 for pressing the sheet 110 against the fixing roller 151. The fixing device 150 heats and pressurizes the toner image transferred to the sheet 110 to fix it on the sheet 110. On the other hand, the fuser 160 is arranged downstream of the fuser 150 in the transport direction in which the sheet 110 is conveyed. The fuser 160 includes a fixing roller 161 having a heater for heating the sheet and a pressurizing roller 162. For example, the gloss of the toner image on the sheet 110 may be increased, or the image may be fixed on the sheet 110 having a large amount of heat required for fixing thick paper or the like. In this case, the sheet 110 that has passed through the fuser 150 is conveyed to the fuser 160.

When the toner image is fixed on the sheet 110 such as plain paper or thin paper, the sheet 110 that has passed through the fixing device 150 is conveyed along the conveying path 130 that does not pass through the fixing device 160. The flapper 131 guides the sheet 110 to the fuser 160 or guides it to the transport path 130.

The flapper 132 is a guiding member that switches between guiding the sheet 110 to the transport path 135 and guiding the sheet 110 to the transport path 139 leading to the outside. The sheet 110 transported along the transport path 135 is transported to the reversing portion 136. When the reversing sensor 137 provided in the transport path 135 detects the rear end of the sheet 110, the transport direction of the sheet 110 is reversed. The flapper 133 is an guiding member that switches between guiding the sheet 110 to the transport path 138 for double-sided printing and guiding the sheet 110 to the transport path 135. When the face-down paper ejection mode is executed, the sheet 110 is conveyed to the conveying path 135 by the flapper 133, and is ejected from the image forming apparatus 100. The flapper 134 is a guiding member that guides the sheet 110 into a transport path 139 for discharging paper from the image forming apparatus 100. When the double-sided printing mode is selected, the flapper 133 guides the sheet 110 to the transport path 138. The sheet 110 is transported to the secondary transfer roller 114 again via the transport path 138. As a result, an image is formed on the second surface of the sheet 110.

An in-line sensor (ILS) 200 for measuring a measurement image on the sheet 110 is arranged in the transport path 135. The ILS200 is a so-called spectroscopic sensor. The four ILS 200s may be arranged side by side in a direction orthogonal to the transport direction of the sheet 110, for example. As a result, the measurement images in four rows are detected in parallel. The ILS 200 is an example of a measuring means provided in a transport path and measuring a measurement image on a sheet.

The operation unit 180 has a display unit for displaying information to the operator and an input unit for the operator to input information (number of printed images, print mode, etc.). The reader unit 400 has a unit having a light source, an optical system, and a CCD sensor, and a platen, and reads an image of a document placed on the platen. The reader unit 400 executes a scanning operation when the document is placed on the platen by the operator and the scanning start button of the operating unit 180 is pressed. When the scanning operation is executed, the light emitted from the light source is reflected by the document placed on the document table, and the reflected light from the document is imaged on the CCD sensor via an optical system such as a lens. .. When the reflected light from the document is imaged on the CCD sensor, the reading data corresponding to the document is acquired. The read data is composed of, for example, data of three color components of R (red), G (green), and B (blue). The reader unit 400 converts the read data into yellow, magenta, cyan, and black image data.

<In-line sensor>
FIG. 2 shows the ILS200. The ILS 200 includes a white LED 201, a diffraction grating 202, a line sensor 203, a calculation unit 204, and a memory 205. The white LED 201 irradiates the measurement image 220 on the sheet 110 with light. The diffraction grating 202 disperses the light reflected from the measurement image 220 for each wavelength. The line sensor 203 includes n (n pixels) light receiving elements. The calculation unit 204 performs various calculations based on the light intensity value of each pixel of the line sensor 203. The memory 205 stores various data.

The ILS200 detects the light intensity of the reflected light at intervals of 10 [nm] from 380 [nm] to 720 [nm]. In this case, n is 34. The calculation unit 204 has, for example, a spectroscopic calculation unit that calculates the spectral reflectance based on the light intensity value of each pixel of the line sensor 203, a Lab calculation unit that calculates the value of L * a * b *, and the like. You may. Even if the ILS 200 has a lens 206 that collects the light emitted from the white LED 201 on the measurement image 220 on the sheet 110 and the light reflected from the measurement image 220 on the diffraction grating 202. good.

The ILS 200 has a white reference plate 250. The ILS 200 uses the white reference plate 250 to adjust the amount of light of the white LED 201. For example, the ILS 200 causes the white LED 201 to emit light in a state where the sheet 110 does not pass through the measurement position of the ILS 200, and receives the light reflected from the white reference plate 250 by the line sensor 203. The calculation unit 204 adjusts the light emission intensity of the white LED 201 so that the light intensity value of a predetermined pixel of the line sensor 203 becomes a predetermined value.

The calculation unit 204 is based on the detection result P (λ) of the line sensor 203 corresponding to the reflected light from the measurement image and the detection result W (λ) of the line sensor 203 corresponding to the reflected light from the white reference plate 250. , The spectral reflectance R (λ) of the measurement image is calculated based on Equation 1.

R (λ) = P (λ) / W (λ) ・ ・ ・ (1)
The calculation unit 204 calculates the density from the spectral reflectance R (λ). For example, the absolute concentration may be calculated according to the spectral sensitivity calculation defined in ISO-5 / 3.

<Control system>
FIG. 3 shows a control system of the image forming apparatus 100. In this example, the DFE (digital front end) 500 is connected to the image forming apparatus 100. The DFE500 is an image processing device that performs raster image processing, color conversion, and the like.

The CPU 300 is a control circuit that controls each part of the image forming apparatus 100. The ROM 304 is a storage device that stores a control program executed by the CPU 300 to execute various adjustments, processes, and the like. The RAM 309 is a system work memory for operating the CPU 300. The I / F unit 302 is an interface (communication circuit) that connects to the DFE500 and receives image data (eg, bitmap information with attributes) output from the DFE500. The attribute is information indicating the type of the image object included in the image data input to the DFE500. Attributes include, for example, photographs, graphics (graphics), text (text), and the like. The gradation correction unit 316 executes gradation correction processing on the image data input from the reader unit 400 or the I / F unit 302. That is, the gradation correction unit 316 functions as a correction means for converting image data based on the gradation correction conditions. The print unit 101 functions as an image forming means for forming an image on the sheet based on the image data corrected by the correcting means. The gradation correction unit 316 individually executes gradation correction for each image data of YMCK. COPY, which means copying, may be added as an attribute to the image data input from the reader unit 400. The gradation correction unit 316 executes gradation correction with reference to the LUT associated with the attribute stored in the memory 310. LUT is an abbreviation for a look-up table, and may be called a gradation correction condition or a gradation correction table. The halftone processing unit 317 also executes halftone processing (halftone processing) according to the attribute. The reason why the halftone processing is changed according to the object is as follows. The characters printed on the sheet 110 have not only straight lines but also curved lines. Therefore, the outline of the character cannot be reproduced smoothly unless the number of lines on the screen is increased. On the other hand, if half-toning is performed on a photograph using a screen with a high number of lines, it may not be possible to reproduce an image having a uniform density. Therefore, the gradation correction unit 316 executes the halftone processing suitable for the object and converts the image data based on the LUT corresponding to the halftone processing.

The reason why gradation correction is necessary is as follows. When the state of the developer in the developing device 112 or the temperature or humidity inside the image forming apparatus 100 changes, the density characteristic (gradation characteristic) of the image formed by the image forming apparatus 100 changes. The gradation correction unit 316 sets the input value (image signal value) of the image data to the print unit 101 so that the density characteristic (gradation characteristic) of the image formed by the print unit 101 becomes the ideal density characteristic. It is converted into a signal value for forming an image of a target density.

The gradation correction unit 316 reads a gradation correction table (γLUT) according to an attribute or a screen from the memory 310, and converts image data based on the γLUT. LUT_SC1 is a gradation correction table corresponding to an image screen. LUT_SC2 is a gradation correction table corresponding to a text screen. LUT_SC3 is a gradation correction table corresponding to a COPY screen. The gradation correction table LUT_SC4 is a gradation correction table corresponding to the error diffusion method. LUT_SC1, LUT_SC2, LUT_SC3 and LUT_SC4 correspond to conversion conditions for converting image data. The γLUT generation unit 307 is a first calibration unit that updates these γLUTs by executing the first calibration. As a result, the density characteristics of the image are maintained at ideal characteristics even if the state of the developer, the internal temperature, and the humidity change. The printer controller 301 including the γLUT generation unit 307 may function as the first generation means. The first generation means controls the transport means to transport the sheet, and controls the image forming means to form the sheet a first pattern image including a plurality of first measurement images. Further, the first generation means controls the measuring means to measure the first pattern image on the sheet, converts the measurement result of the first pattern image into the first measurement data by the conversion means, and sets the gradation correction condition. (1) Generate based on measurement data.

The gradation correction unit 316 may be realized by an integrated circuit such as an ASIC, or may be realized by the CPU 300 executing a program. ASIC is an abbreviation for a special purpose integrated circuit. Further, the gradation correction unit 316 may convert the image data based on the gradation correction table, or may convert the image data based on the conversion formula.

The halftone processing unit 317 applies half toning suitable for the type (attribute) of the image to the image data converted by the gradation correction unit 316. The halftone processing unit 317 converts image data related to an image and image data related to graphics based on an image screen so that a photograph or a graphic becomes an image having excellent gradation. The halftone processing unit 317 converts the image data related to the text based on the text screen so that the characters are printed clearly. When the operator selects the error diffusion method, the halftone processing unit 317 converts the image data based on the error diffusion method. Here, for example, when moire occurs in a high-resolution image, the operator selects an error diffusion method in order to suppress moire. The halftone processing unit 317 converts the image data of the document read by the reader unit 400 based on the COPY screen.

The image data screened by the halftone processing unit 317 is output to the print unit 101. For example, the halftone processing unit 317 outputs yellow image data to the station 120. The print unit 101 forms an image based on the image data input from the halftone processing unit 317 on the sheet 110.

The pattern generator 305 outputs measurement image data used for the first calibration. The halftone processing unit 317 executes half toning on the measurement image data output from the pattern generator 305. The image screen is applied to the measurement image data for updating the LUT_SC1 which is the gradation correction table corresponding to the image screen. The text screen is applied to the measurement image data for updating the LUT_SC2 which is the gradation correction table corresponding to the text screen. The COPY screen is applied to the measurement image data for updating the LUT_SC3, which is the gradation correction table corresponding to the COPY screen. Error diffusion is applied to the measurement image data for updating LUT_SC4, which is a gradation correction table corresponding to error diffusion. The half-toned measurement image data is transferred to the print unit 101. The print unit 101 forms a measurement image on the sheet 110 based on the measurement image data transferred from the halftone processing unit 317. The CPU 300 conveys the sheet 110 on which the measurement image is formed toward the ILS 200, and causes the ILS 200 to measure the measurement image on the sheet 110. The ILS 200 calculates the spectral reflectance of the measurement image 220 by the calculation unit 204 and outputs it to the density conversion unit 306.

The density conversion unit 306 converts the measurement result of the YMC measurement image into a density value using the statusA filter. The density conversion unit 306 converts the measurement result of the K (black) measurement image into a density value using a visual filter. The statusA filter and visual filter are arithmetic methods defined by ISO-5 / 3. The printer controller 301 controls the image formation conditions based on the measurement result (density value) converted by the density conversion unit 306, and generates a gradation correction table. The printer controller 301 has, for example, an LPW adjusting unit 308 that adjusts the laser intensity of the exposure apparatus 103, and a γLUT generation unit 307 that generates a gradation correction table. The LPW adjusting unit 308 determines the intensity of the laser so that the maximum value of the density of the measurement image becomes the target maximum density. The γLUT generation unit 307 generates a gradation correction table (γLUT) so that the gradation characteristics of the measurement image become ideal gradation characteristics. The measurement image is formed for each color and for each screen.

FIG. 4 shows the DFE500. The CPU 501 controls each part of the DFE 500 by executing a control program stored in the ROM 502. The ROM 502 and the RAM 503 are storage devices such as a memory. The operation unit 504 includes an input device for inputting an instruction to the DFE 500 (eg, an instruction for executing the second calibration), a display device for displaying information, and the like. The network IF 505 is a communication circuit that communicates with a PC (personal computer) 560 or the like. The CPU 501 receives image data and output conditions from the PC 560 via the network IF 505. The output conditions include, for example, the type of sheet 110 and the like. The CPU 501 transfers the image data and the output conditions to the control unit 508.

The RIP unit 509 of the control unit 508 analyzes the input image data, determines the attributes of each object, and converts it into bitmap information. The bitmapped image data is input to the color conversion unit 510. The color conversion unit 510 executes color conversion using the color conversion profile 541 corresponding to the output format (sRGB or Adobe RGB). The color conversion profile 541 is a kind of conversion table. The color-converted image data is input to the gradation correction unit 511. The gradation correction unit 511 corrects the gradation characteristics of the image data using the gradation correction table (γLUT542) according to the output condition (sheet type), and generates bitmap data with attributes. The CPU 501 transmits the bitmap data with attributes to the I / F unit 302 via the printer IF506.

The second calibration unit 521 executes DFE calibration. DFE calibration is a process of creating or updating γLUT542 so that a predetermined target gradation is achieved for each type of sheet. For example, the second calibration unit 521 causes the test pattern generation unit 513 to generate measurement image data, and transmits the measurement image data to the I / F unit 302. As a result, the image forming apparatus 100 forms the measurement image on the sheet 110. The sheet 110 on which the measurement image is formed may be called a test chart. The operator has a commercially available colorimeter 570 connected to the USB IF 507 read the test chart. The colorimeter 570 is also an image sensor. The second calibration unit 521 generates γLUT542 for each type of sheet by using the color measurement data acquired from the colorimeter 570, the image data for measurement, and the target gradation for each type of sheet. That is, γLUT542 for each type of sheet is generated so that the target gradation is realized. For example, γLUT for coated paper, γLUT for plain paper, γLUT for thick paper, and γLUT for thin paper are generated. The second calibration unit 521 stores the generated γLUT 542 in the memory 514 in association with the type of sheet.

The test chart for the second calibration may be read by the ILS200. However, in this case, the density conversion unit 512 converts the measurement result of the ILS 200 input through the printer IF 506 into the measurement result of the colorimeter 570. As a result, even though the ILS200 is used, the measurement result as if the colorimeter 570 is used can be obtained. The reason why such a conversion process is necessary is that the target gradation is determined by using the colorimeter 570. The operator may want to use the colorimeter 570 according to his preference. On the other hand, the operator may find it troublesome to connect the colorimeter 570 to the DFE500 and manually scan the DFE500 each time the second calibration is performed. Therefore, a density conversion unit 512 is provided so that the ILS 200 can be used instead of the colorimeter 570. The density conversion table 543 used by the density conversion unit 512 depends on the reading characteristics of the ILS 200 and the reading characteristics of the colorimeter 570. Therefore, the table creation unit 522 creates the density conversion table 543 according to the colorimeter 570. When the CPU 501 is instructed to create the density conversion table 543, the table creation unit 522 causes the test pattern generation unit 513 to output measurement image data. The image data for measurement is output to the I / F unit 302 via the printer IF506. The image forming apparatus 100 generates a test chart for creating the density conversion table 543. The ILS200 measures a measurement image on a test chart. The measurement result is concentrated by the density conversion unit 306 and transmitted to the DFE500 through the I / F unit 302. On the other hand, the test chart is also measured by the colorimeter 570. In this way, the table creation unit 522 creates a density conversion table 543 that converts the measurement result of the ILS 200 so that the measurement result of the ILS 200 matches the measurement result of the colorimeter 570, and sets the density conversion table 543 in the density conversion unit 512. do. In this way, the table creation unit 522 functions as a second generation means. The second generation means controls the transport means to transport the sheet, and the image forming means causes the sheet to form a second pattern image including a plurality of second measurement images. Further, the second generation means controls the measuring means to measure the second pattern image on the sheet. Further, the second generation means acquires the second measurement data corresponding to the measurement result of the second pattern image on the sheet output from the sensor. Further, the second generation means generates conversion conditions based on the measurement result of the second pattern image by the measurement means and the second measurement data.

<Test chart>
FIG. 5A shows a test chart 600a used for the first calibration. The measurement image 220a shown in FIG. 5A is arranged in the order of cyan, magenta, yellow, and black in order from the left. A is added to the end of the component (object) of the test chart for ILS200. According to FIG. 5A, a plurality of measurement images 220a are arranged according to the measurement rule of ILS200. The measurement image 220a may be called a test patch or a test pattern. A plurality of measurement images 220a are formed on one test chart 600a for each CMYK. If there are four types of half toning, four sheets are required. That is, one test chart 600a is created for each half toning. The formation position of the measurement image 220a is determined according to the measurement position of the ILS200. The cyan measurement image group is formed on the test chart 600a so that the cyan ILS200 can be measured. The magenta measurement image group is formed on the test chart 600a so that the magenta ILS200 can be measured. The yellow measurement image group is formed on the test chart 600a so that the yellow ILS200 can be measured. The black measurement image group is formed on the test chart 600a so that the black ILS200 can be measured.

Further, a tip margin 681a is provided at the tip of the test chart 600a in the transport direction. The position bar 682a indicates the beginning of the measurement image group. That is, the position bar 682a is a trigger bar for causing the ILS 200 to start measuring the measurement image group. A rear end margin 689a is provided at the rear end of the test chart 600a in the transport direction.

FIG. 5B shows a test chart 600b for the colorimeter 570. The measurement image 220b shown in FIG. 5B is arranged in the order of cyan, magenta, yellow, and black from the left. A b is added to the end of the component of the test chart for the colorimeter 570. The test chart 600b for the colorimeter 570 also requires a front end margin 681b, a position bar 682b, and a rear end margin 689b. Further, the measurement rule of the colorimeter 570 stipulates that a black separator 684 and a white separator 685 must be provided between two adjacent measurement images 220b. When the colorimeter 570 detects the black separator 684 and the white separator 685, it starts the measurement of the next measurement image 220b. The separators 684 and 685 function as marks for identifying the measurement position. Alternatively, the separators 684 and 685 serve as marks for determining the measurement timing. In the ILS200, since the formation position of each measurement image 220a is known, the separators 684 and 685 are unnecessary. Further, the size of the measurement image 220a for the ILS200 may be a variable size such as Amm, Bmm, and Cmm, but the size of the measurement image 220b for the colorimeter 570 must be a constant Amm. Here, the size is the length of the measurement image 220a in the reading direction.

As described above, since the test chart 600a for the ILS200 and the test chart 600b for the colorimeter 570 are different from each other, twice the number of test charts is required to create the density conversion table 543. .. Therefore, this embodiment provides an image forming apparatus 100 capable of reducing the number of sheets 110 on which a measurement image is formed.

Further, unless the ILS 200 and the colorimeter 570 read a measurement image having the same density, it is difficult to create an accurate density conversion table. However, the measurement image 220a for the ILS 200 and the measurement image 220b for the colorimeter 570 are physically formed on different sheets. Therefore, there is a possibility that the densities of the two measurement images 220a and 683b, which should originally have the same density, will be different. That is, since the whiteness and the basis weight of the two sheets also vary, the measurement result of the ILS 200 and the measurement result of the colorimeter 570 are affected by this variation. Therefore, in this embodiment, the ILS 200 and the colorimeter 570 measure the same test image on the same test chart, so that the number of test charts can be reduced and the accuracy of the density conversion table 543 can be improved. Test charts are provided.

● Improved test charts FIGS. 6 (A) and 6 (B) show the improved test chart 600ab. The test chart 600ab is a test chart commonly used by the ILS 200 and the colorimeter 570. The same reference number is assigned to the components already described. FIG. 6A shows the reading direction 695a of the ILS200. FIG. 6B shows the reading direction 695b of the colorimeter 570. The reading direction 695a and the reading direction 695b are different from each other, and are orthogonal to each other in this example. As described above, a plurality of measurement images 220ab are arranged along the reading direction 695a in order to satisfy the measurement rule of ILS200. Further, a plurality of measurement images 220ab are arranged along the reading direction 695b in order to satisfy the measurement rule of the colorimeter 570. This makes it possible to use the same test chart 600ab in common for the ILS200 and the colorimeter 570.

The arrangement of the measurement image 220ab, the front margin 681a, the position bar 682a, and the rear end margin 689a for the ILS200 in FIG. 6A is as described with reference to FIG. 5A. Therefore, the arrangement of these objects for the colorimeter 570 will be described in detail below.

As shown in FIGS. 6A and 6B, the colorimeter 570 moves from left to right in order with a tip margin 681b, a position bar 682a, a white separator 685, and a cyan measurement image 220ab. Read the black separator 684 or the white separator 685. Further, the colorimeter 570 reads the black separator 684 or the white separator 685, the magenta measurement image 220ab and the black separator 684 or the white separator 685 in order while moving from left to right. Further, the colorimeter 570 reads the black separator 684 or the white separator 685, the yellow measurement image 220ab, and the black separator 684 or the white separator 685 in order while moving from left to right. Further, the colorimeter 570 moves from left to right in order to move the black separator 684 or the white separator 685 black measurement image 220ab, the black separator 684 or the white separator 685, and the trailing edge margin 689b. read. The colorimeter 570 reads the CMYK measurement image 220ab in the first row, and then reads the CMYK measurement image 220ab in the second row. The colorimeter 570 executes such a reading process in order until the last line.

As shown in FIG. 6A, a tip margin 681b is provided at the left end of the A4 size test chart 600ab. The width of the tip margin 681b in the main scanning direction (hereinafter referred to as the main scanning width) is, for example, 30 mm. The main scanning direction corresponds to a direction orthogonal to the transport direction in which the image forming apparatus conveys the test chart. Further, in FIGS. 6A and 6B, the main scanning direction is parallel to the reading direction 695b. Further, on the left side of the cyan measurement image 220ab, a position bar 682b that triggers the colorimeter 570 to start measurement is provided. The main scanning width of the position bar 682b is, for example, 22 mm. A white separator 685 is arranged between the position bar 682 and the cyan measurement image 220ab. That is, a white separator 685 is arranged on the left side of the cyan measurement image 220ab. The main scanning width of the white separator 685 is 2 mm. The cyan measurement image 220ab has a main scanning width of 22 mm. A black separator 684 or a white separator 685 is arranged to the right of the cyan measurement image 220ab. Either separator is selected depending on the gradation (signal value) of the cyan measurement image 220ab. For example, a black separator 684 is selected for a gradation measurement image 220ab that is less than a predetermined threshold. A white separator 684 is selected for the image 220ab for measuring gradation having a gradation equal to or higher than a predetermined threshold value. The main scanning width of the black separator 684 or the white separator 685 is 2 mm. When the colorimeter 570 detects the separator to the right of the measurement image 220ab, the colorimeter 570 ends the measurement of the measurement image 220ab.

A solid white portion 687 is arranged between the separator on the right side of the cyan measurement image 220ab and the separator on the left side of the magenta measurement image 220ab. The main scanning width of the solid white portion 687 is 22 mm. The solid white part 687 is read by the colorimeter 570, but not by the ILS200. This is because the solid white portion 687 is provided to satisfy the measurement rule of the colorimeter 570. Further, according to the measurement rule of the colorimeter 570, the solid white portion 687 is also the same measurement target as the measurement image 220ab, so that the size of the solid white portion 687 matches the size of the measurement image 220ab. This meets the requirement for size uniformity of the measurement image.

When the colorimeter 570 reads the black separator 684 or the white separator 685 next to the solid white portion 687, it starts measuring the magenta measurement image 220ab. A black separator 684 or a white separator 685 according to the gradation of the measurement image 220ab is also arranged on the left side and the right side of the magenta measurement image 220ab. When the colorimeter 570 detects the black separator 684 or the white separator 685 to the right of the measurement image 220ab, it ends the measurement of the magenta measurement image 220ab. The solid white portion 687 is also provided between the magenta measurement image 220ab and the yellow measurement image 220ab.

When the colorimeter 570 reads the black separator 684 or the white separator 685 next to the solid white portion 687, it starts measuring the yellow measurement image 220ab. A black separator 684 or a white separator 685 according to the gradation of the measurement image 220ab is also arranged on the left side and the right side of the yellow measurement image 220ab. When the colorimeter 570 detects the black separator 684 or the white separator 685 to the right of the measurement image 220ab, the colorimeter 570 ends the measurement of the yellow measurement image 220ab. The solid white portion 687 is also provided between the yellow measurement image 220ab and the black measurement image 220ab.

When the colorimeter 570 reads the black separator 684 or the white separator 685 next to the solid white portion 687, it starts measuring the black measurement image 220ab. A black separator 684 or a white separator 685 according to the gradation of the measurement image 220ab is also arranged on the left side and the right side of the black measurement image 220ab. When the colorimeter 570 detects the black separator 684 or the white separator 685 to the right of the measurement image 220ab, the colorimeter 570 ends the measurement of the black measurement image 220ab. A rear end margin 689b is provided on the right side of the black separator 684 or the white separator 685 on the right side of the measurement image 220ab. The main scanning width of the rear end margin 689b is, for example, 52 mm.

FIG. 7 shows an example of the measurement result (concentration) of the test chart 600ab by the colorimeter 570. The sub-scan address indicates the line number in the test chart 600ab. On the test chart 600ab, the test images are arranged in the order of the sub-scanning address numbers. The order of the test images is parallel to the sheet transport direction. W shows the measurement result of the solid white part 687. The measurement result of the solid white part 687 is converted into a density through a Visual filter (for black). The density of the solid white portion 687 is unnecessary for the image forming apparatus 100 and the DFE500, but it will be useful when the operator finds a measurement error of the colorimeter 570.

<Flowchart>
FIG. 8 is a flowchart showing a method of creating the concentration conversion table 543. This creation method is executed by the table creation unit 522. When the CPU 501 receives an instruction to create the density conversion table 543 through the operation unit 504, the CPU 501 starts the table creation unit 522. As described above, the table creation unit 522 may be realized by the CPU 501 executing the control program.

In S801, the table creation unit 522 creates a test chart 600ab using the image forming apparatus 100. For example, the table creation unit 522 causes the test pattern generation unit 513 to generate image data for the test chart 600ab. The table creation unit 522 outputs image data, print instructions, and measurement instructions to the I / F unit 302 through the printer IF506. The CPU 300 causes the gradation correction unit 316 and the halftone processing unit 317 to process the image data according to the print instruction, and outputs the image data to the print unit 101. The print unit 101 forms an image on the sheet 110 according to the image data output from the halftone processing unit 317. This creates a test chart 600ab.

In S802, the table creation unit 522 acquires the measurement result of the test chart 600ab by the ILS200. The CPU 300 controls the flapper 132 according to the measurement instruction and guides the test chart 600ab to the transport path 135. The ILS 200 measures the test chart 600ab according to the measurement instruction from the CPU 300, and outputs the measurement result to the concentration conversion unit 306. The density conversion unit 306 converts the measurement result (spectral reflectance) into a density and outputs it to the printer controller 301. The printer controller 301 transfers the measurement result (concentration) to the DFE 500 via the I / F unit 302 according to the transfer instruction from the CPU 300. When the CPU 501 receives the measurement result (concentration), it passes it to the table creation unit 522. The table creation unit 522 stores the measurement result (concentration) by the ILS 200 in the RAM 503. The CPU 300 controls the flappers 133 and 134, and discharges the test chart 600ab read by the ILS 200 to the outside of the image forming apparatus 100.

In S803, the table creation unit 522 outputs a message to the operation unit 504 to prompt the operator to measure with the colorimeter 570. The message may include guidance information or the like indicating a moving (scanning) direction of the colorimeter 570 with respect to the test chart 600ab. The operator moves the colorimeter 570 on the test chart 600ab according to the guidance information. The colorimeter 570 measures the test chart 600ab according to the measurement rule, and outputs the measurement result to the USB IF 507. The conversion process from the measurement result (spectral reflectance) to the measurement result (density) may be executed by the colorimeter 570 or the table creation unit 522.

In S804, the table creation unit 522 acquires the measurement result (density) of the test chart 600ab by the colorimeter 570. The table creation unit 522 receives the measurement result (concentration) from the colorimeter 570 via the USB IF 507 and stores it in the RAM 503.

In S805, the table creation unit 522 reads the measurement result (concentration) of the colorimeter 570 and the measurement result (concentration) of the ILS 200 from the RAM 503, creates a density conversion table 543, and stores it in the memory 514. The density conversion table 543 is a table that converts the measurement result (density) of the ILS 200 into the measurement result (density) of the colorimeter 570, and is created for each of the CMYK.

In S805, the table creation unit 522 sets the density conversion table 543 stored in the memory 514 in the density conversion unit 512. This makes it possible to perform calibration using the ILS 200 even if the calibration is premised on using the colorimeter 570. A typical example of such calibration is the second calibration. In addition, as long as the calibration is premised on the use of the colorimeter 570, this embodiment can be applied even to the calibration performed in the image forming apparatus 100. Here, the measurement rules of the colorimeter, which has become the de facto standard in the market as the colorimeter 570, are introduced. However, this embodiment can also be applied to another colorimeter that the operator wishes to connect to the DFE500. In this case, the arrangement of the measurement image 220ab on the test chart 600ab may satisfy both the measurement rule of the ILS 200 and the measurement rule of the colorimeter 570. That is, in the test chart 600ab, the arrangement of the measurement image 220ab in the first direction may satisfy the measurement rule of the ILS200, and the arrangement of the measurement image 220ab in the second direction may satisfy the measurement rule of the colorimeter 570.

By the way, the test chart used in the second calibration may be the test chart 600a shown in FIG. 5 (A) or the test chart 600ab shown in FIG. 6 (A). .. In any case, the density conversion unit 512 can convert the measurement result of the ILS 200 into the measurement result of the colorimeter 570.

As described above, according to the present embodiment, the image forming apparatus 100 and the DFE 500 capable of reducing the number of sheets on which the measurement image is formed are provided. Further, according to this embodiment, the accuracy of creating the density conversion table 543 that converts the measurement result of the ILS 200 into the measurement result of the colorimeter 570 is also improved. This is because the ILS 200 and the colorimeter 570 can measure the same measurement image on the same sheet even though the measurement rules are different from each other.

[Example 2]
In the first embodiment, one DFE 500 and one image forming apparatus 100 are connected. However, as shown in FIG. 9A, a plurality of image forming devices 100A, 100B, 100C may be connected to the DFE500 mounted on the print server 900 or the like via a network. Here, it is assumed that the layout rule of the test chart for the image forming apparatus 100A is classified into type A. The layout rule of the test chart for the image forming apparatus 100B shall be classified into type B. The layout rule of the test chart for the image forming apparatus 100C shall be classified into type C. Layout rules may be called measurement rules. There are various layout rules for the colorimeter 570 that can be connected to the DFE500. The layout rules of the test chart for the colorimeter 570α shall be classified as type α. The layout rules of the test chart for the colorimeter 570β shall be classified as type β. In such a case, the DFE500 must create a common test chart that satisfies both the layout rule of the ILS200 and the layout rule of the colorimeter 570.

FIG. 10 is a table illustrating various layout rules. The layout rule may be stored in the ROM 502, for example. FIG. 11 shows test charts 600A-600C corresponding to types A-C. FIG. 12 shows test charts 600α and 600β corresponding to types α and β. The same reference numerals are given to the same parts as those already described. A to C, α, and β added to the end of the reference code indicate the type. Types A to C show layout rules due to the type of ILS 200 mounted on the image forming apparatus 100. Type α and type β show layout rules due to the type of colorimeter 570.

As shown in FIG. 10, the type A employs a spectral reflectance sensor as the ILS200. Therefore, one position bar 682A is provided for each patch group in a row. Since the type A does not require the uniformity of the measurement image 220A, a plurality of patch sizes are adopted. The measurement image may be called a test image or a patch. Since the number of sensors is 4, a patch group of 4 rows is provided. As mentioned above, the four rows of patches correspond to YMCK. Since the relationship between the position of each measurement image 220A and the position of the position bar 682A is known, the measurement timing is a specified timing. That is, the measurement timing of the measurement image 220A is determined in advance from the timing at which the ILS 200 detects the position bar 682A, the distance between the position bar 682A and the measurement image 220A, and the transport speed of the test chart 600A.

As shown in FIG. 10, the type B employs an RGB sensor as the ILS200. Therefore, as shown in FIG. 11, two position bars 682B are provided for each patch group in a row. The RGB sensor is more susceptible to the transport speed of the sheet 110 than the spectral reflectance sensor. The measurement timing of the measurement image 220B is corrected by using the plurality of position bars 682B provided on the test chart 600B. Since the type B requires the uniformity of the measurement image 220B, a single patch size is adopted. Since the number of sensors is 4, a patch group of 4 rows is provided. Since the relationship between the position of each measurement image 220B and the position of the position bar 682B is known, the measurement timing is a specified timing. That is, the measurement timing of each measurement image 220B is dynamically corrected based on the detection timing of the position bar 682B.

As shown in FIG. 10, Type C employs an RGB sensor as an in-line sensor. Therefore, as shown in FIG. 11, two position bars 682C are provided for each row. Since the type C requires the uniformity of the measurement image 220C, a single patch size is adopted. Since the number of sensors is two, two rows of patch groups are provided. This means that the number of test charts 600C is larger than the number of test charts 600B. Since the relationship between the position of each measurement image 220C and the position of the position bar 682C is known, the measurement timing is a specified timing. That is, the measurement timing of each measurement image 220C is dynamically corrected based on the detection timing of the position bar 682C.

As shown in FIG. 10, the type α employs a spectral reflectance sensor as the sensor of the colorimeter 570. In type α, the size of the measurement image 220α is arbitrary, but uniformity is required. Therefore, a single patch size is adopted. As shown in FIG. 12, the measurement timing of each measurement image 220α is determined based on the position bar 682α or the separators 684 and 685. As described above, the white separator 685 may be adopted depending on the density of two adjacent measurement images 220α.

As shown in FIG. 10, the type β employs a spectral reflectance sensor as the sensor of the colorimeter 570. In type β, the size of the measurement image 220β is arbitrary, but uniformity is required. Therefore, a single patch size is adopted. As shown in FIG. 12, the measurement timing of each measurement image 220β is determined based on the position bar 682β. Further, in the type β, a diamond-shaped transport marker 1201 for controlling the transport speed of the test chart 600β is required. The transport marker 1201 is provided along two sides (eg, long sides) parallel to the transport direction of the test chart 600β. When the colorimeter 570 moves, the transport direction of the test chart 600β means the moving direction of the colorimeter 570.

● Creation of a common test chart FIG. 13 is a flowchart showing a process of generating a common test chart. This generation process corresponds to S801 described above. This generation process is started when the operator inputs an instruction to create a concentration conversion table through the operation unit 504. The CPU 501 executes the following processing by loading the creation program stored in the ROM 502 into the RAM 503. When the CPU 501 executes the creation program, the CPU 501 functions as a test pattern generation unit 513. As described above, the test pattern generation unit 513 may be mounted on the control unit 508 instead of the CPU 501. In this case, the following processing is executed by the test pattern generation unit 513.
-In S1301, the CPU 501 accepts the selection (designation) of the type of ILS200 through the operation unit 504. As shown in FIG. 14A, the CPU 501 may display the UI 1400 for creating the density conversion table on the display device of the operation unit 504. UI is an abbreviation for user interface. The UI 1400 has a selection unit 1401 for accepting a selection of the type of ILS200. The operator selects one of the selection candidates displayed on the selection unit 1401.
-In S1302, the CPU 501 accepts the selection (designation) of the colorimeter type through the operation unit 504. As shown in FIG. 14 (A), the UI 1400 has a selection unit 1402 for accepting selection of the type of colorimeter 570. The operator selects one of the selection candidates displayed on the selection unit 1402.
-In S1303, the CPU 501 acquires the layout rule corresponding to the selected ILS200 type and the layout rule corresponding to the selected colorimeter 570 type from the ROM 502. The ROM 502 stores layout rules corresponding to each of the plurality of types. The CPU 501 may acquire a layout rule corresponding to the type of ILS200 and a layout rule corresponding to the type of the selected colorimeter 570 from a server connected via a network. Each type and the layout rule may be linked via the model name of the image forming apparatus 100 or the model name of the colorimeter. The model name may be a product code or the like.
-In S1304, the CPU 501 determines a layout that satisfies both layout rules. The CPU 501 analyzes both layout rules and determines the layout of the measurement image 220 as follows.

● Presence / absence of separator CPU 501 analyzes the layout rule for the colorimeter 570 and determines whether the layout rule defines that the separators 684 and 685 are provided. As shown in FIG. 10, type α requires separators 684, 685. In this case, it is necessary to make the scanning direction of the ILS 200 orthogonal to the scanning direction of the colorimeter 570. That is, the CPU 501 adopts an orthogonal layout as shown in FIG. 6 (A). As shown in FIG. 15, when type α is selected, one of the test charts 600Aα, 600Bα, 600Cα adopting an orthogonal layout is created. For example, if type A is selected, the CPU 501 creates a test chart 600Aα. In the test charts 600Aα, 600Bα, and 600Cα, the lateral direction (right direction) is the scanning direction of the colorimeter 570. Therefore, separators 684 or 685 are provided on the left and right sides of each measurement image 220. In the orthogonal layout, the position bars 682A, 682B, 682C for the ILS200 and the position bars 682α for the colorimeter 570 are provided independently.

On the other hand, type β does not require a separator 684. Therefore, the CPU 501 adopts a parallel layout in which the scanning direction of the ILS 200 and the scanning direction of the colorimeter 570 are parallel. As shown in FIG. 15, when type β is selected, one of the test charts 600Aβ, 600Bβ, 600Cβ adopting a parallel layout is created. In the parallel layout, the position bar 682 for the ILS200 and the position bar 682 for the colorimeter 570 are shared. As shown in FIG. 15, the test charts 600Aβ, 600Bβ, and 600Cβ are provided with common position bars 682Aβ, 682Bβ, and 682Cβ, respectively.

● Number of sensors CPU501 analyzes the layout rule of ILS200 and acquires the number of ILS200. In order to reduce the number of test charts 600 and shorten the reading time of the measurement image 220, a plurality of ILS 200s may be arranged in the transport path. The CPU 501 provides the test chart 600 with a number of patch sequences that match the number of sensors defined by the layout rules of the ILS 200. As shown in FIG. 15, since the number of sensors of types A and B is 4, the number of patch rows is 4. An example of this is the test charts 600Aα, 600Bα, 600Aβ, 600Bβ. Since the number of type C sensors is two, the patch row is two rows. An example of this is the test charts 600Cα, 600Cβ. As described above, the number of the type A and B test charts 600 will be half the number of the type C test charts 600, and the measurement time will be halved.

● Sensor type The CPU 501 analyzes the layout rule of the ILS 200 and acquires the sensor type. The CPU 501 determines the number of position bars 682 for the ILS200 per row based on the type of sensor defined by the layout rules of the ILS200. Since the type A is a spectral reflectance sensor, the CPU 501 is provided with one position bar 682 per row. An example of this is the test charts 600Aα, 600Aβ. Since the types B and C are RGB sensors, the CPU 501 is provided with two position bars 682 per row. An example of this is the test charts 600Bα, 600Cα, 600Bβ, 600Cβ. As shown in the test charts 600Bα, 600Cα, 600Bβ, 600Cβ, position bars 682B, 682C, 682Bβ, 682Cβ are provided at a plurality of different positions in the scanning direction of the ILS200.

● Presence / absence of transfer marker The CPU 501 analyzes the layout rule for the colorimeter 570 and determines whether or not the layout rule defines that the transfer marker 1201 is provided. Depending on the type of colorimeter 570, a transport marker 1201 is required for transporting the test chart 600. According to the layout rules shown in FIG. 10, type β requires a transport marker 1201. When the layout rule of the colorimeter 570 requires the transfer marker 1201, the CPU 501 provides the transfer marker 1201 on the common test chart. An example of this is the test charts 600Aβ, 600Bβ, 600Cβ.

In S1305, the CPU 501 generates image data for realizing the test chart 600 according to the determined layout rule. The image data may be PDF data. In this case, the PDF data is converted into bitmap data by the RIP unit 509 and color-converted by the color conversion unit 510.

In S1306, the CPU 501 transmits a print instruction of the test chart 600 to the image forming apparatus 100. The image data of the CPU 501 test chart 600 is also transmitted to the image forming apparatus 100. These are transmitted through the printer IF506. As a result, the image forming apparatus 100 creates the test chart 600 by forming the measurement image 220 on the sheet 110 according to the print instruction and the image data.

[Example 3]
In the second embodiment, the CPU 501 analyzes the layout rule and dynamically creates a common test chart. However, the image data of the test chart 600 corresponding to the combination of the type of ILS200 and the type of the colorimeter 570 may be stored in the ROM 502 in advance.

As shown in FIG. 16, when the type of ILS200 is selected in S1301 and the type of the colorimeter 570 is selected in S1302, the CPU 501 proceeds to S1601. In S1601, the CPU 501 acquires the image data of the test chart 600 corresponding to the combination of the type of the ILS 200 and the type of the colorimeter 570 from the ROM 502. Image data of the test chart 600 corresponding to various combinations is stored in the ROM 502. In S1306, the CPU 501 transmits the image data to the image forming apparatus 100 together with the print instruction. The type of image data may be one that can be developed by the RIP unit 509. For example, a CMYK file in any format such as TIFF format, PDF format, EPS format, PS format, etc. is stored in ROM 502. The CPU 501 is generated by the RIP unit 509 based on the CMYK file, and the gradation correction unit 511 transmits the gradation-corrected image data to the image forming apparatus 100 as needed. The image data (bitmap data) generated from the CMYK file does not need to pass through the color conversion unit 510.

[Example 4]
As shown in FIG. 9B, the DFE500 may be mounted on the PC910 which is an information processing device. That is, the CPU of the PC 910 may execute the program to function as the DFE 500 described above. The RIP unit 509 may be mounted on the RIP server 920. The PC 910 acquires or creates image data of the common test chart and transmits it to the RIP server 920. As shown in FIG. 14B, the CPU 501 of the DFE500 mounted on the PC910 displays the UI1400 on the operation unit 504. The UI 1400 is provided with a save button 2404. The name of the image data of the common test chart is received through the CPU 501 and the operation unit 504, and the image file of the accepted name is saved in the ROM 502 (hard disk drive or the like). This means that the CPU 501 can skip the image data creation process when the same layout combination is selected. The RIP unit 509 of the RIP server 920 expands the received image data and transmits it to the image forming apparatus 100. As a result, the image forming apparatus 100 creates a common test chart. The image forming apparatus 100 transmits the measurement result of the common test chart by the ILS 200 to the DFE 500 mounted on the PC 910. The DFE500 mounted on the PC910 acquires the measurement result of the common test chart using the colorimeter 570. The DFE500 mounted on the PC910 creates a concentration conversion table based on these.

<Summary>
As shown in FIG. 1 and the like, the station 120 and the like are examples of image forming means for forming a plurality of measurement images 220ab on the sheet 110. The ILS 200 is an example of a first measuring means for measuring the measurement image 220ab formed on the sheet 110. The colorimeter 570 is an example of a second measuring means or sensor for measuring the measurement image 220ab formed on the sheet 110. The table creation unit 522 is an example of a creation means for creating conversion conditions. As described above, the first pattern image is formed on the sheet 110 in order to create or update the gradation correction condition. Also, a second pattern image is formed to create or update the density conversion table. The first pattern image and the second pattern image may be the same. The table creation unit 522 is an example of the second generation means. The table creation unit 522 indirectly controls the transport means to transport the sheet, and causes the sheet to form a second pattern image including a plurality of second measurement images by the image forming means. The table creation unit 522 controls the measuring means to measure the second pattern image on the sheet. In addition, the table creation unit 522 acquires the second measurement data corresponding to the measurement result of the second pattern image on the sheet output from the sensor. The table creation unit 522 generates conversion conditions based on the measurement result of the second pattern image by the measuring means and the second measurement data. The second pattern image includes a plurality of images for the second measurement. The plurality of images for the second measurement read by the ILS 200 form the first image group. Further, a plurality of images for second measurement read by the colorimeter 570 form a second image group. As described above, the plurality of second measurement images forming one image group and the plurality of second measurement images forming the second image group may be the same. The density conversion table used by the density conversion unit 512 is for converting the measurement result by the ILS200 into the measurement result of the colorimeter 570 based on the measurement result of the measurement image by the ILS200 and the measurement result of the measurement image by the colorimeter 570. This is an example of the conversion condition of. The image forming apparatus 100 forms the first image group and the second image group on the sheet 110. The first image group has a plurality of measurement images that are sequentially measured by the ILS 200 scanning along the first direction. In FIG. 6A, the plurality of cyan measurement images 220ab arranged in the sub-scanning direction (conveying direction of the test chart) are an example of the first image group. The second image group has a plurality of measurement images that are sequentially measured by scanning by a colorimeter 570 different from the first measuring means along a second direction different from the first direction. In FIG. 6A, the cyan, magenta, yellow, and black measurement images 220ab arranged in the main scanning direction are an example of the second image group. As shown in FIGS. 6A and 9, the plurality of measurement images 220ab in the first image group and the plurality of measurement images 220ab in the second image group are the same measurement images. That is, in the second pattern image, a plurality of images for second measurement, which are sequentially measured by the measuring means scanning along the transport direction, form a first image group. In the second pattern image, a plurality of images for second measurement, which are sequentially measured by the sensor scanning along the direction orthogonal to the transport direction, form a second image group. Since the measurement image 220ab of the ILS 200 and the measurement image 220ab of the colorimeter 570 are shared in this way, the number of 110 sheets for the test chart is reduced. Further, according to this embodiment, the accuracy of creating the density conversion table 543 that converts the measurement result of the ILS 200 into the measurement result of the colorimeter 570 is also improved. This is because the ILS 200 and the colorimeter 570 can measure the same measurement image on the same sheet even though the measurement rules are different from each other.

As shown in FIG. 6A and the like, among a plurality of measurement images belonging to the first image group, the upstream of the measurement image 220ab that is first measured by the colorimeter 570 scanning along the second direction. A measurement start mark is formed on the side so that the colorimeter 570 recognizes the start of measurement. That is, the position bar 682b is an example of the measurement start mark. The upstream side may be called the scanning start side. As shown in FIG. 6 (A), among a plurality of measurement images belonging to the first image group, the measurement image that is first measured by the colorimeter 570 scanning along the second direction is on the downstream side of the measurement image. An end mark is formed on the colorimeter 570 to recognize the end position of the first measured image for measurement. The downstream side may be referred to as the scanning end side. The black separator 684 and the white separator 685 provided on the right side of the cyan measurement image 220ab are examples of end marks. In FIG. 9, the black separator 684 and the white separator 685 provided on the left side of the black measurement image 220ab on the even-numbered rows are examples of end marks. As shown in FIG. 6A, the image density (optical density) of the black separator 684 and the white separator 685 can be determined according to the spectral reflectance of the first measured image for measurement. This is because the larger the optical density difference between the separator and the measurement image, the easier it is to distinguish between the two.

In FIG. 6A and the like, among the plurality of measurement images belonging to the first image group, the magenta, cyan, and blank measurement images 220ab are obtained by scanning the magenta, cyan, and blank measurement images 220ab along the second direction. This is an example of a measurement image measured after the second. Separator 684 and 685 for recognizing the start position and end position of each measurement image are formed on the upstream side and the downstream side of the measurement images 220ab of zenta, cyan, and blank, respectively. As described above, the image densities of the separators 684 and 685 are determined according to the spectral reflectance of the measurement image 220ab adjacent to the separator.

As described with reference to FIG. 6A and the like, the test chart 600ab may be provided with an n-column first image group and an m-row second image group. As shown in FIG. 4, the density conversion unit 512 is an example of a conversion means for converting the measurement result of the ILS 200 into the measurement result of the colorimeter 570 using the conversion conditions. The second calibration unit 521 is an example of an update means for updating the image formation condition (γLUT) of the image forming apparatus 100 based on the measurement result of the colorimeter 570 acquired by the density conversion unit 512. This makes it possible to use the ILS200 instead of the colorimeter 570. The image formation condition may be a gradation correction condition for correcting the gradation characteristic of the image data. The image formation condition may be the color management profile used by the color conversion unit 510.

The flapper 134 and the transport roller are examples of transport means for transporting the sheet 110 along the transport path. The ILS 200 measures the measurement image 220ab formed on the sheet 110 conveyed by the conveying means. The colorimeter 570 measures the measurement image 220ab formed on the sheet 110 ejected from the image forming apparatus 100.

According to this embodiment, the DFE 500 is an image processing apparatus in which an ILS 200 for measuring a measurement image 220 ab formed on a test chart 600 ab and a colorimeter 570 for measuring a measurement image 220 ab formed on a test chart 600 ab are connected. This is an example. The ILS 200 may be indirectly connected to the DFE 500 via a plurality of interfaces.

As shown in FIG. 8, S801 is an example of a step of forming a plurality of measurement images 220ab on the sheet 110. S802 is an example of a step of measuring a plurality of measurement images 220ab by relatively moving the ILS 200 along the first direction with respect to the plurality of measurement images 220ab formed on the sheet 110. S804 is an example of a step of measuring a plurality of measurement images 220ab by relatively moving the colorimeter 570 along the second direction with respect to the plurality of measurement images 220ab formed on the sheet 110. S805 is an example of a process of creating conversion conditions for converting the measurement result by the ILS200 into the colorimeter 570 based on the measurement result by the ILS200 and the measurement result by the colorimeter 570.

As shown in FIG. 6A, in the test chart 600ab, the arrangement of the plurality of measurement images 220ab in the first direction is an arrangement according to the measurement rule of ILS200. As shown in FIG. 6B, in the test chart 600ab, the arrangement of the plurality of measurement images 220ab in the second direction is an arrangement according to the measurement rule of the colorimeter 570. By providing such a test chart 600ab, the number of sheets 110 on which the measurement image 220ab is formed is reduced. In addition, the accuracy of creating a density conversion table that converts the measurement result of the ILS 200 into the measurement result of the colorimeter 570 is also improved.

The DFE500 is an example of an image processing device that causes the image forming apparatus 100 to form a plurality of test images (example: measurement image 220) read by the first measuring instrument and the second measuring instrument on the same sheet. ILS200 is an example of the first measuring instrument. The colorimeter 570 is an example of a second measuring instrument. ROM 502 is an example of storage means. The ROM 502 stores a first layout rule that defines a layout of a plurality of test images so that the first measuring instrument can measure a plurality of test images. The ROM 502 stores a second layout rule that defines the layout of the plurality of test images so that the second measuring instrument can measure the plurality of test images. The CPU 501 and the printer IF 506 are examples of transmission means for transmitting image data having a plurality of test images arranged on a sheet so as to satisfy both the first layout rule and the second layout rule to the image forming device 100. .. In this way, the test chart 600 is generated so that both the layout rule of the ILS 200 and the layout rule of the colorimeter 570 are satisfied. This test chart 600 becomes a common test chart that can be measured by both the ILS 200 and the colorimeter 570. Therefore, the number of sheets on which the measurement image such as the measurement image 220 is formed is reduced. Further, since the ILS 200 and the colorimeter 570 measure the same test chart 600, a measurement error due to the difference in the sheet 110 does not occur.

17 (A) and 17 (B) show the functions of the CPU 501 and the test pattern generation unit 513. The selection unit 1701 is realized by, for example, the CPU 501, the operation unit 504, and the UI 1400. The selection unit 1701 is an example of a selection means for selecting the type of the first measuring instrument (example: types A, B, C) and the type of the second measuring instrument (example: types α, β). The rule acquisition unit 1702 acquires the first layout rule corresponding to the type of the first measuring instrument selected by the selection unit 1701 from the ROM 502. The rule acquisition unit 1702 acquires the second layout rule corresponding to the type of the second measuring instrument selected by the selection unit 1701 from the ROM 502. The ROM 502 stores a rule group 1780 including these layout rules. The layout determination unit 1703 analyzes the first layout rule and the second layout rule, and determines the layout of a plurality of test images on the sheet so as to satisfy both the first layout rule and the second layout rule. The CPU 501 and the printer IF 506 transmit image data for forming a plurality of test images on the sheet according to the determined layout to the image forming apparatus 100. In this way, the image data for the test chart 600 may be dynamically generated. This eliminates the need to prepare image data in advance. Therefore, this embodiment is advantageous from the viewpoint of effectively utilizing the storage capacity of the ROM 502.

The separator determination unit 1711 functions as a determination means for determining whether or not the second layout rule stipulates that the separator 684 is provided between the plurality of test images. A second layout rule may stipulate that a separator 684 be provided between a plurality of test images. In this case, the layout unit 1716 functions as a layout means for arranging a plurality of test images on the sheet so that the scanning direction of the first measuring instrument and the scanning direction of the second measuring instrument are orthogonal to each other. In this case, the layout unit 1716 further sets a first trigger bar (eg, position bar 682A) for causing the first measuring instrument to recognize the measurement start timings of a plurality of test images along the first side of the sheet 110. Deploy. The layout unit 1716 arranges a second trigger bar (eg, a position bar 682α) for causing the second measuring instrument to recognize the measurement start timings of a plurality of test images along the second side of the sheet 110.

On the other hand, the second layout rule may not specify that a separator 684 is provided between a plurality of test images. In this case, the layout unit 1716 arranges a plurality of test images on the sheet so that the scanning direction of the first measuring instrument and the scanning direction of the second measuring instrument are parallel to each other. Further, the first trigger bar and the second trigger bar may be shared. The layout unit 1716 may arrange a common trigger bar along the first side of the sheet 110. The first trigger bar is an image object for causing the first measuring instrument to recognize the measurement start timings of a plurality of test images. The second trigger bar is an image object for causing the second measuring instrument to recognize the measurement start timings of a plurality of test images. In FIG. 15, the position bars 682Aβ, 682Bβ, and 682Cβ are examples of common trigger bars.

The marker determination unit 1712 analyzes the second layout rule and determines whether or not the second layout rule defines that the transfer marker 1201 serving as the transfer reference of the second measuring instrument is provided. When the second layout rule defines that the transport marker 1201 serving as the transport reference of the second measuring instrument is provided, the layout unit 1716 arranges the transport marker 1201 along the second side of the sheet 110.

The type determination unit 1713 may analyze the first layout rule and determine the type of ILS200 (eg, spectral reflectance sensor, RGB sensor). As shown in FIG. 10, the ILS 200 may be an RGB sensor provided in the transport path of the image forming apparatus 100. In this case, the layout unit 1716 provides a plurality of first trigger bars at different positions in the transport direction of the seat 110. As shown in FIG. 15, the position bars 682B, 682C, 682Bβ, and 682Cβ are examples of a plurality of first trigger bars.

The number determination unit 1714 analyzes the first layout rule and determines the number of ILS200s. The layout unit 1716 arranges a plurality of test images in a row of a number matching the number of sensors of the first measuring instrument defined by the first layout rule. That is, the layout unit 1716 determines the number of patch rows so as to match the number of sensors acquired by the number determination unit 1714.

As shown in FIG. 17B, the ROM 502 is a storage means for storing image data for forming a plurality of test images on a sheet for each combination of the type of the first measuring instrument and the type of the second measuring instrument. This is an example. The image data group 1791 is image data (eg, YMCK file, PDF file, etc.) corresponding to various combinations. The selection unit 1701 selects the type of the first measuring instrument and the type of the second measuring instrument. The data acquisition unit 1790 functions as a transmission means for reading image data corresponding to the combination of the type of the first measuring instrument and the type of the second measuring instrument selected by the selection unit 1701 from the ROM 502 and transmitting the image data to the image forming apparatus 100. do.

As shown in FIG. 15, the plurality of second measurement images are arranged on the sheet so as to satisfy both the first layout rule and the second layout rule. The first layout rule defines the layout of a plurality of second measurement images so that the measuring means (eg, ILS200) can measure the plurality of second measurement images. The second layout rule defines the layout of a plurality of second measurement images so that the sensor (eg, colorimeter 570) can measure the plurality of second measurement images.

As described above, the ROM 502 stores a program that causes the computer to function as each means of the image processing apparatus. ROM 502 is an example of a computer-readable storage medium.

100 ... image forming device, 120-123 ... station, 200 ... in-line sensor, 570 ... colorimeter, 522 ... table creation unit

Claims (10)

An image processing device that causes an image forming device to form a plurality of test images read by the first measuring device and the second measuring device on the same sheet.
A first layout rule that defines the layout of the plurality of test images so that the first measuring instrument can measure the plurality of test images, and the second measuring instrument can measure the plurality of test images. A storage means for storing the second layout rule that defines the layout of the plurality of test images, and
A transmission means for transmitting image data having the plurality of test images arranged on the sheet so as to satisfy both the first layout rule and the second layout rule to the image forming apparatus .
Based on the measurement results of the plurality of test images by the first measuring instrument and the measurement results of the plurality of test images by the second measuring instrument, the measurement results by the first measuring instrument are used as the measurement results of the second measuring instrument. An image processing apparatus having a creation means for creating a conversion condition to be converted. A determining means for analyzing the first layout rule and the second layout rule and determining the layout of the plurality of test images on the sheet so as to satisfy both the first layout rule and the second layout rule. Have more
The first aspect of the present invention is characterized in that the transmitting means transmits image data for forming the plurality of test images on the sheet according to the layout determined by the determining means to the image forming apparatus. Image processing equipment. The determination means is
A determination means for determining whether or not the second layout rule stipulates that a separator is provided between the plurality of test images.
When the second layout rule specifies that a separator is provided between the plurality of test images, the scanning direction of the first measuring instrument and the scanning direction of the second measuring instrument are orthogonal to each other. The image processing apparatus according to claim 2, further comprising a layout means for arranging the plurality of test images on the sheet. The layout means is for causing the first measuring instrument to recognize the measurement start timing of the plurality of test images when the second layout rule stipulates that a separator is provided between the plurality of test images. The first trigger bar is arranged along the first side of the sheet, and the second trigger bar for causing the second measuring instrument to recognize the measurement start timing of the plurality of test images is along the second side of the sheet. The image processing apparatus according to claim 3, wherein the image processing apparatus is arranged. If the second layout rule does not specify that a separator is provided between the plurality of test images, the layout means may have a scanning direction of the first measuring instrument and a scanning direction of the second measuring instrument. The image processing apparatus according to claim 3, wherein the plurality of test images are arranged on the sheet so as to be parallel to each other. The layout means is for causing the first measuring instrument to recognize the measurement start timing of the plurality of test images when the second layout rule does not specify that a separator is provided between the plurality of test images. The first trigger bar and the second trigger bar for causing the second measuring instrument to recognize the measurement start timing of the plurality of test images are arranged along the first side of the sheet as a common trigger bar. The image processing apparatus according to claim 5. When the layout means defines that the second layout rule provides a transport marker that serves as a transport reference for the second measuring instrument, the layout means arranges the transport marker along the second side of the sheet. The image processing apparatus according to claim 5 or 6. The first measuring instrument is an RGB sensor provided in the transport path of the image forming apparatus.
The image processing apparatus according to claim 4, wherein the layout means arranges a plurality of the first trigger bars at different positions in the transport direction of the sheet. 3. The image processing apparatus according to one item. Further having a selection means for selecting the type of the first measuring instrument and the type of the second measuring instrument,
The determination means acquires the first layout rule corresponding to the type of the first measuring instrument selected by the selection means from the storage means, and the type of the second measuring instrument selected by the selection means. The image processing apparatus according to any one of claims 2 to 9, wherein the second layout rule corresponding to the above is acquired from the storage means.

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