JP5907191B2 - Sample page creation method, program, and image forming system - Google Patents

Description

  The present invention relates to a sample page creation method, program, and image forming system, and more particularly to a sample page creation method, program, and image forming system in an image forming system equipped with a colorimetric unit.

  In the printing field, there are colors that require accurate color reproducibility, such as corporate colors used for company logos and the like. Such colors are reproduced by using specially formulated special ink in offset printing (hereinafter, such colors are referred to as “spot colors”). ).

  On the other hand, in the printing market where an offset printing type image forming apparatus is often used, cases of using an electrophotographic type or ink jet type image forming apparatus are increasing.

  In an electrophotographic image forming apparatus, printing is performed using a dedicated library (spot color library) in which reproduction of special colors is approximated by a combination of toners of basic colors of C, M, Y, and K (for example, Patent Document 1).

  Further, in the electrophotographic image forming measure, since the special color is reproduced by the combination of the basic color toners as described above, the output result varies depending on various factors such as machine differences and machine fluctuation variations. Therefore, patch images generated with different toner amounts with different signal intensities are formed, and their density and color information are manually measured or visually compared with a color guide, and C and M of the spot color library are obtained. , Y, K values (printer device values) are edited and color matching is performed.

  For spot colors, color reproduction stability is important and is strictly controlled. In variable printing or the like that performs mass printing, there is a problem that even if color matching is performed before mass printing is started, the color changes as a large number of sheets are printed. In this case, when the amount of change exceeds a certain threshold value, the spot color is readjusted.

  At this time, it is only necessary to refer to the past output and make color adjustments for this purpose, but to do so, it is necessary to extract the spot color print location from the mass printed, and in order to make a judgment on readjustment There was a problem that a lot of labor was required and it was not easy.

  In Patent Document 2, after printing a color chart in which a plurality of blocks composed of a plurality of color patches are arranged in the main scanning direction in an inkjet printing apparatus, a colorimeter is temporarily attached to the printing apparatus to perform color measurement. After that, it is disclosed that a color difference (ΔE) between a color measurement result of each block and a reference block and a color difference with respect to a past output result are printed in the vicinity of each color patch.

JP 2010-278494 A JP 2012-228836 A

  However, the printing apparatus described in the cited document 2 can compare the color differences, but for a spot color that requires strict management, how the actual color changes with respect to the past color is shown. Cannot be compared visually.

  In order to achieve such a problem, an object of the present invention is to provide a sample page creation method capable of easily outputting a sample page that allows visual comparison of spot colors.

1. It is determined whether or not a spot color is included in the print data. If a spot color is included, a spot color table in which spot color identification information and a printer device value indicating a density signal of a basic color are associated is used. A spot color setting unit for setting printer device values for spot colors,
An image forming unit that forms a color image on a recording medium based on a printer device value;
A colorimeter for measuring the color of an output image formed on a recording medium by the image forming unit and acquiring color information;
A color conversion unit that calculates a printer device value indicating a basic color density signal from color information;
Holding a colorimetric result of the colorimeter for an output image of a spot color as a history colorimetric result;
Determining whether the sample page creation condition is satisfied;
If it is determined that the sample page creation condition is satisfied, the first color sample image by the printer device value calculated on the basis of the features of the history colorimetry result, the by該特color printer device values determined from the spot color table Creating a sample page formed on a recording medium with two color sample images;
How to create a sample page with

2. In the sample page,
2. The first color sample image, wherein the history color measurement result of a spot color and a color difference between the history color measurement result and the original color information of the spot color are shown. To create a sample page.

3. In the sample page,
For the second color sample image, estimated color information for the second color sample image and a color difference between the estimated color information and the original color information of the spot color are shown. 3. The method for creating the sample page according to 1 or 2 above.

4). In the step of holding the history color measurement result , the printer device value applied to the colorimetric output image is further held,
In the sample page:
Indicating the retained printer device value for the first color sample image;
4. The sample page creation method according to any one of 1 to 3, wherein a printer device value applied to the second color sample image is indicated for the second color sample image.

5. The color conversion unit includes a look-up table used when calculating a printer device value based on color information,
Performing the step of holding the history colorimetric result and then updating the lookup table before executing the step of creating the sample page;
In the step of creating the sample page, the color conversion unit determines a printer device value of the first color sample image by using an updated look-up table. How to create the sample page described in 1.

6). Before executing the step of creating the sample page after executing the step of holding as the history color measurement result ,
A step of outputting a plurality of patch images having different printer device values for reproducing the history color measurement result, and acquiring a correspondence relationship between the printer device value and color information from the color measurement result of the output patch image; Have
In the step of creating the sample page, the color conversion unit determines a printer device value of the first color sample image from the acquired correspondence relationship. How to create the sample page described in.

  7). The sample page creation conditions are as follows: (1) Every time a predetermined number of prints are exceeded, (2) When the color difference between the original color information of the special color and the output image of the special color exceeds a predetermined value, (3) The historical color measurement 7. The method for creating a sample page according to any one of 1 to 6, wherein the color difference between the result and the output image of the spot color is at least one of when a predetermined value is exceeded.

8). When executing one print job that includes spot color output,
The sample page creation conditions further target the same print job,
8. The sample page creation method according to claim 7, wherein the history color measurement result is a color measurement of the first spot color output image in the print job.

9. In the step of holding as the history colorimetry result , the output condition of at least one of the print setting of printing and the ambient temperature and humidity at the time of printing is further held,
In the sample page,
9. The sample page creation method according to any one of 1 to 8, wherein the held output condition is indicated for the first color sample image.

  10. 10. The sample page creation method according to any one of 1 to 9, wherein the original color information of the special color is outside a color gamut that can be reproduced by a color image formed on a recording medium by the image forming unit. .

11. It is determined whether or not a spot color is included in the print data. If a spot color is included, a spot color table in which spot color identification information and a printer device value indicating a density signal of a basic color are associated is used. A spot color setting unit for setting printer device values for spot colors,
An image forming unit that forms a color image on a recording medium based on a printer device value;
A colorimeter for measuring the color of an output image formed on a recording medium by the image forming unit and acquiring color information;
A color conversion unit that calculates a printer device value indicating a basic color density signal from color information;
A program that causes an image system to create a sample page,
Holding a colorimetric result of the colorimeter for an output image of a spot color as a history colorimetric result;
Determining whether the sample page creation condition is satisfied;
When it is determined that the sample page creation condition is satisfied, the first color sample image based on the printer device value calculated based on the historical color measurement result of the spot color and the spot color based on the printer device value of the spot color determined from the spot color table. Creating a sample page formed on a recording medium with two color sample images;
A program that causes a computer to run.

12 In the sample page:
12. The above-mentioned 11, wherein the first color sample image shows the history color measurement result of a spot color and a color difference between the history color measurement result and the original color information of the spot color. Program.

13. It is determined whether or not a spot color is included in the print data. If a spot color is included, a spot color table in which spot color identification information and a printer device value indicating a density signal of a basic color are associated is used. A spot color setting unit for setting printer device values for spot colors,
An image forming unit that forms a color image on a recording medium based on a printer device value;
A colorimeter for measuring the color of an output image formed on a recording medium by the image forming unit and acquiring color information;
A color conversion unit that calculates a printer device value indicating a basic color density signal from color information;
A history holding unit that holds the color measurement result of the output image of the spot color as the history color measurement result;
Control means;
An image forming system comprising:
When it is determined that the sample page creation condition is satisfied, the control unit performs the first color sample based on the printer device value calculated by the color conversion unit based on the history color measurement result of the spot color held in the history holding unit. The image forming unit controls the image forming unit to form a sample page on which the image and the second color sample image based on the printer device value of the spot color determined from the spot color table are determined by the spot color setting unit. An image forming system.

14 In the sample page,
14. The above-mentioned 13, wherein the first color sample image shows the history color measurement result of the spot color and the color difference between the history color measurement result and the original color information of the spot color. Image forming system.

15. With an operation display,
In the sample page, a plurality of color sample images having different printer device values in a plurality of stages are printed together with the second color sample image.
A correction unit capable of correcting the color of the spot color by a user inputting a printer device value or an identifier of the color sample shown in each of the plurality of color sample images from the operation display unit; 15. The image forming system as described in 13 or 14, above.

When it is determined that the sample page creation condition is satisfied, the sample page creation method according to the present invention includes a first color sample image based on a printer device value calculated based on a historical color measurement result of a spot color, and the original color of the spot color. by creating a sample page and a second color sample image by the calculated printer device values were formed on a recording medium based on the information, Ri Do and comparable with easily visually change of features of color, more It becomes possible to perform the color determination of the spot color effectively.

1 is a diagram illustrating an example of a schematic configuration of an image forming system A according to the present embodiment. 2 is a block diagram illustrating a hardware configuration example of an image forming system A. FIG. It is an example of a spot color table. 6 is a diagram illustrating an LUT used in a color conversion unit 243. FIG. 6 is a diagram illustrating a relationship between a color gamut reproducible with CMYK toner of the image forming system A and a special color (special color C). FIG. It is an enlarged view of FIG. 5A. It is a control flowchart regarding a history storage process. It is an example of a history record. It is an example of a setting page of sample page creation conditions. It is a figure explaining the relationship of the color difference with respect to the original color information S0 of the spot color C and the first colorimetric value Sa. It is a figure which shows the control flow regarding the sample page creation which the control part 2 performs. It is a figure explaining the subroutine of a sample page creation process. An example of actual job execution is shown. It is an example of a printing result. It is an example of a history record. It is an example of the history record shown with a 1st color sample image. It is an output example of a sample page. In 2nd Embodiment, it is a figure which shows the control flow regarding the sample page creation which the control part 2 performs. It is an example of the chart for special color reproduction used for correction. It is an output example of a sample page.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

<Image forming system A>
FIG. 1 is a diagram illustrating an example of a schematic configuration of an image forming system A according to the embodiment. FIG. 2 is a block diagram illustrating a hardware configuration example of the image forming system A. FIG. 3 is an example of a spot color table (“spot color library”) for associating spot color identification information with color information, and FIG. 4 is a diagram for explaining an LUT (look-up table) used for color conversion processing. It is. FIG. 5 is a schematic diagram illustrating a color reproduction area (hereinafter referred to as “color gamut”) and a special color that can be output by the image forming system.

  Hereinafter, a schematic configuration of the image forming system A will be described with reference to FIGS.

  As shown in FIG. 1, the image forming system A includes an image forming apparatus A1 and a post-processing apparatus A2.

  The image forming apparatus A1 includes an operation unit / display unit 1, a control unit 2, an image forming unit 3, a paper feeding unit 4, and a color measuring unit 5.

  The operation unit / display unit 1 includes a touch panel in which an operation unit of a touch sensor is arranged on a display unit such as an LCD, and the user can perform setting operations of the image forming apparatus A1 and the post-processing apparatus A2. .

  As shown in FIG. 2, the control unit 2 that controls the entire image forming system A includes a CPU 21, a memory 22, an HDD 23, an image processing unit 24, and a communication I / F 25.

  The CPU 21 is a control circuit composed of a multi-core processor or the like that executes control of the above-described units and various arithmetic processes according to a program. Each function that can be executed by the control unit 2 is executed by the CPU 21 corresponding to the function. It is demonstrated by doing.

The memory 22 is a high-speed accessible main storage device that temporarily stores programs and data as a work area. The memory 22 is, for example, a DRAM (Dynamic
Random Access Memory), SDRAM (Synchronous)
A dynamic random access memory (SRAM), a static random access memory (SRAM), or the like is employed.

  The HDD 23 is a large-capacity auxiliary storage device that stores various programs including an operating system and various data relating to processing functions such as an LUT (Look Up Table).

The image processing unit 24 includes a RIP unit 241, a spot color setting unit 242, a color conversion unit 243, and the like. The RIP unit 241 performs RIP (Raster Image Processor) processing that expands print data described in PDL such as PCL, PS, and PDF received from a PC or the like into bitmap data. The color information of each pixel of the bitmap data is, for example, sRGB, L ^* a ^* b ^*, or spot color identification information (ID or spot color name).

The spot color identification information may be standardized or may be set uniquely by the image forming apparatus. The spot color table shown in FIG. 3 is stored in the HDD 23 or the like. When the spot color setting unit 242 analyzes each pixel and detects that the color information is designated by the spot color, the spot color setting unit 242 refers to the spot color table shown in FIG. FIG. 3A is a diagram for explaining an LUT. A spot color signal as input color information is converted into a CMYK printer device value. Here, the “printer device value” is a CMYK density signal corresponding to the basic color of the image forming unit 3 and is density information unique to the device. FIG. 3B is a specific example of the LUT. In the following, as shown in FIG. 3B, a spot color signal and a printer device value or a spot color signal and a spot color original color information (L ^* a ^* b ^* ) are associated with each other. In particular, it will be referred to as a “spot color table”. By using this spot color table, a printer device value or the like can be determined based on identification information such as a spot color name or ID.

  The spot color setting unit 242 identifies the type of the spot color from the identification information and embeds a specific printer device value of the spot color corresponding to the spot color type in the target pixel by referring to the spot color table. At this time, arrangement position information (position coordinates on the XY plane) for the special color paper is handed over to the control unit 2, and the control unit 2 stores the position information in the HDD 23 as necessary.

FIG. 4 is a diagram for explaining an LUT used in the color conversion unit 243. FIG. 4 is a diagram in which an L ^* a ^* b ^* signal as input color information is converted into a CMYK signal as an output.

The color conversion unit 243 uses the LUT as shown in FIG. 4 to convert the color information of each pixel into a CMYK density signal (hereinafter referred to as “printer device value”) corresponding to the basic color of the image forming unit 3. Convert. In this embodiment, an example in which L ^* a ^* b ^* is used as color information will be described. However, other types of color information may be used as long as the color is device-independent.

  The communication I / F 25 is an interface for communicating with an external device (for example, a personal computer PC) via a network (LAN), and uses standards such as Ethernet (registered trademark), token ring, FDDI, and Wi-Fi. It is done. In addition, an interface for BlueTooth (registered trademark), infrared communication, and USB communication may be provided.

  The image forming unit 3 forms an image on a sheet by electrophotography. Specifically, a developing unit including an exposure unit corresponding to each color toner corresponding to the basic colors of CMYK, a drum photoreceptor, and a developing device, an intermediate transfer belt for superimposing toner formed by the developing unit, and an intermediate transfer belt A secondary transfer roller that transfers the color toner image formed on the paper, a paper transport unit that transports the paper, a fixing device that fixes the toner image to the paper by heating and pressurizing the toner image transferred to the paper, etc. Prepare.

  The sheet feeding unit 4 includes a plurality of sheet feeding trays, and conveys the sheets stored in each sheet feeding tray to the image forming unit 3 one by one.

  The color measurement unit 5 is provided in the conveyance path (in-line) between the image forming unit 3 and the post-processing apparatus A2, and enables the sensor 58 to perform color measurement on the image on the sheet being conveyed. The colorimetric unit 5 performs colorimetry by uniformly irradiating the paper with light from a light source (lamp) and forming an image of the reflected light on the line-shaped sensor 58 through the light receiving lens.

  The sensor 58 is composed of, for example, three types of RGB sensors, measures color values based on output values (RGB values) from the three types of sensors for each part of the color image, and outputs measurement information. The sensor 58 has a sufficient length in the width direction of the sheet to be conveyed (axial direction of the conveyance roller) and can measure the color of the entire area of the sheet.

  The post-processing apparatus A2 performs various post-processing such as stapling, punching, and bookbinding on the paper conveyed from the image forming apparatus A1.

<Correspondence between color gamut L and spot color>
5A and 5B are diagrams for explaining the relationship between the color gamut that can be reproduced with the CMYK toner of the image forming system A and the special color, and the L ^* a ^* b ^* space is on the a ^* b ^* plane. It is a projection. FIG. 5B is an enlarged view of FIG. 5A and corresponds to the area of the broken line K.

5A and 5B, a region L (a region surrounded by a hexagon of af) is a color gamut reproducible with the CMYK toner of the image forming system A. Symbol S0 indicates the color of the special color C (see FIG. 3), which is one of the special colors. The width of the color gamut L depends mainly on the color material of the toner. In general, the image forming unit 3 cannot reproduce all L ^* a ^* b ^* spaces. The color S0 of the spot color C that is actually highly saturated is located outside the color gamut L (outside the color gamut).

In the present embodiment, for the color S0 of the special color C, the special color setting unit 242 converts each pixel into a CMYK printer device value using the special color table shown in FIGS. Become. The image forming unit 3 has a problem that while printing a large number of sheets, the color of the image output on the paper changes even with the same printer device value. In this case, a certain color is output. Therefore, color re-correction processing is performed as necessary. This color re-correction process involves changing the printer device value of the spot color table by comparing the output image with a color sample that the user has faithfully reproduced the color, or a large number of patches output with different printer device values. A new LUT describing the relationship between L ^* a ^* b ^* and the printer device value is created and updated by measuring the image with the colorimetric unit 5, and the printer device value of the spot color table is changed based on the updated LUT. To include.
As shown in FIG. 5B, when color re-correction processing is performed on a spot color S0 that is out of the color gamut, the color of the image output after correction is set to a different color as shown by colors Sa to Sc. There is.

  For an output image of the spot color S0 that is outside such a color gamut, it must be output in any color within the color gamut, and the output color (for example, color Sa) changes ( For example, there is a problem of Sc).

  In the following, the output of the special color (the “first color sample” described later corresponding to the color Sa) for which the special color outside the color gamut is output and how it is changed (described later) ( A method of creating a sample page to be output on one sheet so that it can be visually compared with a “second color sample” (to be described later) corresponding to the color Sc will be described.

<Control Flow of First Embodiment>
A sample page creation process in the first embodiment will be described with reference to FIGS.

  First, the history saving process will be described. FIG. 6 is a diagram showing a control flow processed by the control unit 2. If a print job execution instruction is input in step S11, it is analyzed in step S12 whether a spot color is included in the received print data. If not, normal printing is executed and the process ends. (Step S16). If a spot color is included (step S12: Yes), printing is executed (step S13), the spot color setting position analyzed by the spot color setting unit 242 is referred to, and the spot color output image is obtained by the color measuring unit 5. Color measurement is performed (step S14).

In step S15, the history is stored. FIG. 7 is an example of a history record obtained by history storage processing. The history record includes a history ID, job name, job page, date and time of history acquisition, spot color identification information, history color measurement result (L ^* a ^* b ^* ), history for spot color original color information (see FIG. 3). The color difference of the color measurement result, the printer device value (0 to 100), the XY coordinate position (mm) in the paper of the output image, the paper type, the process speed, the print setting such as the fixing temperature, the environment information, etc. are saved. .

<Sample page creation conditions>
Next, sample page creation conditions will be described. FIG. 8 is an example of a sample page creation condition setting screen displayed on the operation unit / display unit 1 or the monitor screen of a PC connected to the LAN. The column 8a in the figure is a check box, and the selected spot color is a sample page creation target. Sample setting conditions are set in columns 8b and 8c.

  In the example shown in the figure, the condition set for the spot color A (hereinafter referred to as “condition A”) is every 1000 output sheets. The history storage process shown in FIG. 6 is executed for the first output image of the spot color A, and thereafter, sample pages are output every 1000 sheets. For example, when printing 30 copies of a printed material in which the special color A is used only on the cover for one copy of 100 pages, a history storage process is executed for the output image of the spot color on the first page (cover). Thereafter, a sample page is output every time 10 copies are printed. An example of the sample page will be described later.

  The condition set for the spot color C (hereinafter referred to as “condition B”) is the target value, that is, when the color difference between the original color information of the spot color C and the color measurement result of the spot color output image is 5 or more. Create a sample page.

Here, the color difference is ΔE ^* ab represented by the following formula (1). In this paper, it is simply described as color difference or ΔE.

  The condition set for the spot color G (hereinafter referred to as “condition C”) is to create a sample page when the color difference from the initial output value is 3 or more. The initial output value is the color measurement result of the output image of the spot color that is the first target of the same job.

  Note that the conditions A and C can be further limited to the same print job. Further, these conditions A to C may be set in combination by a plurality of AND or OR conditions. Further, a sample page creation button may be provided on the setting screen as shown in FIG. 8, and when this is simply selected, the sample page may be output assuming that the condition is satisfied.

FIG. 9 is a diagram for explaining the relationship of the color difference with respect to the original color information S0 of the spot color C and the first colorimetric value Sa. This figure corresponds to FIG. 5B, and the same reference numerals are assigned to items that are common to FIG. 5B. In the drawing, a broken-line circle Δ5 indicates a circle with a radius 5 centered on the color S0, and a broken-line circle Δ3 indicates a circle with a radius 3 centered on the color Sa. In the figure, for ease of explanation, it is assumed that there is no color difference in the L ^* direction (a direction perpendicular to the a ^* b ^* plane).

  The colors in Zone A shown in the figure have a color difference from the original color information S0 of less than 5 and a color difference from the first colorimetric value Sa of less than 3, so both the conditions B and C for the special color C It will not satisfy.

  The colors in Zone B have a color difference of less than 5 with the original color information S0, but since the color difference with the first colorimetric value Sa is 3 or more, Condition B is not satisfied but Condition C is satisfied. Become.

  The colors in ZoneC satisfy the condition B because the color difference from the original color information S0 is 5 or more and the color difference from the first colorimetric value Sa is less than 3. Do not meet.

  Also, as setting of the sample print layout, setting of whether to display the past output in the 8d column, the output environment in the 8e column, the correction patch in the 8f, and the highlight of the changed portion in the 8g column is set. Can be selected. These output examples will be described in an example of a sample page described later.

<Create sample page>
FIG. 10 is a diagram illustrating a control flow relating to sample page creation executed by the control unit 2.

  If a print job execution instruction is input in step S21, it is determined in the subsequent step S22 whether or not a sample page output condition is set in the received print job. If there is no output condition setting, normal printing is performed. Execution is completed (step S26). If the output condition is set (step S22: Yes), the printing is continued while the output condition is not met (step S24: No) (step S23), and the output condition is met (step S24). : Yes), the sample page creation process of step S25 is executed.

  FIG. 11 is a diagram for explaining a subroutine of the sample page creation process (step S25). In step S251, spot color history information is acquired. The target record is a record of identification information identical to the identification information of the target spot color.

  In step S252, it is determined whether or not the setting is necessary to simulate the past output (output reproduction). If this is not a necessary setting (S252: No), a sample page indicating the numerical data of the history information is output and the process ends. This corresponds to the case where the check is not made in the 8d column of FIG.

  If the 8d column in FIG. 8 is checked (step S252: Yes), the process proceeds to step S253, and it is determined whether simulation measurement is necessary. This is determined, for example, based on whether or not the LUT needs to be updated. For example, it can be determined from the number of prints since the last update of the LUT, environmental changes such as temperature and humidity, or changes in colorimetric results of patch images for density confirmation. If necessary (step S253: Yes), the LUT is updated in subsequent steps S254 to S256.

  Specifically, in step S254, a measurement chart is output. This is a measurement chart composed of several hundred color patches made up of combinations of CMYK printer device values. The measurement chart is output over a plurality of pages. Measurement of these color patches is performed (step S254), and interpolation calculation is performed based on the color measurement results to obtain thousands of color correspondences, thereby calculating new LUTs and storing them in the HDD 23. By saving, the previous LUT is updated.

In step S257, the printer device value of “first color sample” simulating the history color measurement result is calculated. The printer device value is calculated using the history colorimetry result (L ^* a ^* b ^* ) stored in the history record as shown in FIG. 7 and the current LUT (hereinafter, “simulated printer device value”). ”). Since the printer device value is calculated using the current appropriate LUT, the history color measurement result can be reproduced with high accuracy. When a plurality of histories are stored, as a default setting, a plurality of simulation printer device values are calculated based on all the history color measurement results (for example, an example of FIG. 16 described later). However, the present invention is not limited to this, and it is possible to use only the history colorimetry result of the oldest or latest time stamp, or to use an arbitrary history colorimetry result according to the user's selection.

  In step S258, the printer device value of “second color sample” is determined using the spot color table.

  In step S259, the first color sample image and the second color sample image are arranged on the sheet using the simulation printer device value calculated in step S257 and the printer device value determined in step S258. Output a sample image. The shape of the color sample image at this time may be a color reflecting the logo shape as long as it is a special color applied to a company logo, or may be a simple circle or square shape.

<Example>
Next, a specific example will be described with reference to FIGS.

  FIG. 12 shows an example of actual job execution. One print job # 001 is a job of 10,000 pages, and includes a special color A as a special color. Since the colorimetric setting is ON for the 3rd page and the 9998th page, the control unit 2 performs control so that the colorimetric unit 5 performs the color measurement of the target special color based on the special color position information. To do.

  In FIG. 12, the printer device value applied at that time for the spot color is shown as a reference. This data is recorded as a history when the page ID is a history ID, and this data is a series of values together with the color measurement results. Recorded as a history record.

  FIG. 13 shows an example of the printing result. In the example shown in FIG. 13, three sheets are extracted from the continuous printing. For the first and third sheets, since a logo mark using a special color is printed at the position corresponding to the arrow in the figure, the color measurement unit 5 performs color measurement at the position, and the color measurement result Is sent to the control unit 2.

  FIG. 14 is an example of a history record. This indicates that original color information and a plurality of history information are recorded for a plurality of spot colors. For each history ID, a history record having a mode as shown in FIG. 7 is linked.

  Next, a sample page output example will be described with reference to FIGS. FIG. 15 is a list of history information shown together with the first color sample image extracted from the history record, and FIG. 16 is an output example of the sample page 9. In the figure, output images of three first color sample images 91 (91a to 91c) and one second color sample image 92 are formed on one sheet of paper. In this figure, the shape of the color sample image is the same shape (circular shape) as the logo mark shown in FIG.

  For the first color sample image 91, the simulation printer device value used for the output is shown. This simulation printer device value is calculated in S257 of FIG. The history column 96 in FIG. 16 shows the date when the history is acquired as output information, the color measurement result at that time, and the printer device value. Since the first color sample image uses the simulation printer device value calculated by the latest LUT, the color information described in the color measurement result is faithfully reproduced.

  The upper part of the sample page shows the estimated color information and the color difference between the color information and the original color information, along with the second color sample image 92 formed using the printer device value calculated based on the original color information. ing. “Estimated color information” displays the result of color measurement performed on the target spot color immediately before. In FIG. 16, when the condition B (ΔE ≧ 5 with the original color information) is satisfied, the sample page is output by satisfying the setting of outputting the sample page, and this estimated color information Specifically, the color measurement result immediately before the condition B is satisfied (for example, several sheets before the sample page) is shown. When there is no previous color measurement result, in order to determine the estimated color information, a sheet on which a spot color output image is formed is printed, and this is measured by the color measuring unit 5, and this is estimated. It may be used as color information.

  As described above, in this embodiment, when it is determined that the sample page creation condition is satisfied, the first color sample image based on the simulation printer device value calculated based on the historical color measurement result of the spot color, and the spot color By creating a sample page in which the second color sample image based on the printer device value determined by the table is formed on the recording medium, it is possible to easily visually compare the change in the color of the special color, which is more effective. It is possible to determine the color of the spot color.

  In the sample page, the color difference between the first color sample image and the original color information and the printer device value can be used as auxiliary information when making a comparison judgment.

<Control Flow of Second Embodiment>
Next, a second embodiment will be described. FIG. 17 is a diagram illustrating a control flow related to sample page creation executed by the control unit 2 in the second embodiment. In the second embodiment, the measurement for simulation is simply performed by limiting the surroundings of the target special color.

  In the same figure, the flow after the case of S253 in FIG. 11 is shown, and the flow other than the flow shown in the same figure is the same as the first embodiment shown in FIG. 10 and FIG. To do.

In step S264 in FIG. 17, a chart for spot color reproduction is output. FIG. 18 is an example of a spot color reproduction chart used for correction. The center c1 of the spot color reproduction chart is output with the printer device value calculated from the current LUT and the history color measurement result of the spot color. The directions d1 to d6 are directions corresponding to Y, R, M, B, C, and G on the a ^* b ^* plane of the L ^* a ^* b ^* space. A plurality of patch images having different printer device values are arranged around the center c1 so that a ^* b ^* is gradually changed. Although not shown in the figure, the other two patch groups in which the lightness and darkness are changed in the L ^* direction with respect to the 19 patch groups as shown in the figure are also formed on the sheet.

In step S265, color measurement of these patches formed on the chart is performed. As shown in step S266, the printer device value of the first color sample image is determined if there is a patch of the same color (L ^* a ^* b ^* ) as the historical color measurement result on the chart. The printer device value is determined as the simulation printer device value. If the printer device value does not exist, the simulation printer device value is determined by interpolating colors between a plurality of patches.

  On the other hand, for the second color sample image, the printer device value of the spot color is determined using the spot color table in step S267.

  In step S268, a sample page is created using the respective printer device values calculated in S266 and S267.

  As described above, in the second embodiment, since the color patch is formed around the spot color and the measurement for the simulation is performed, the man-hours required for updating the LUT compared to the case where the color patch is formed over the entire color gamut. Can be reduced.

<Third Embodiment>
Next, a third embodiment will be described. FIG. 19 shows a sample page 9b in the third embodiment. The example shown in FIG. 8 is an output example when all of the 8e column (output environment), 8f (correction patch), and 8g column (highlighted display) are checked in FIG.

  The sample page 9b shows output conditions held as history for the first color sample images 93a to 93c. The output conditions referred to here are print settings stored in the history record as shown in FIG. 7 and the ambient temperature and humidity environment. The print settings include paper type, process speed, and fixing set temperature.

  At that time, items (signs 99a, 99b, 99c, etc.) that have changed greatly from the previous history are highlighted so that they can be distinguished from other items.

In the same figure, a ^* b ^* is gradually changed around the first color sample images 93a to 93c in the six directions d1 to d6 on the a ^* b ^* plane as in FIG. In addition, six patch images having different printer device values are formed on a sheet, and each is assigned a number. The user can correct the spot color by selecting the most suitable color from the patches and specifying this color. For example, if the user determines that a color whose color is changed in the direction 6 (Green color direction) is preferable to the patch of 93a whose output information is 9/1, the user operates the A6 corresponding to the number. By inputting through a designation screen (not shown) displayed on the copy / display unit 1, the printer device value used for the output of A6 is reflected in the spot color table. Thereafter, the control unit 2 determines the printer device value using the updated spot color table.

  The program for operating the control unit 2 may be provided by a computer-readable recording medium such as a USB memory, a flexible disk, or a CD-ROM, or may be provided online via a network such as the Internet. . In this case, the program recorded on the computer-readable recording medium is usually transferred and stored in a ROM, HDD, or the like. Further, this program may be provided as, for example, a single application software, or may be incorporated in the software of the apparatus as one function of the image forming system A.

  In addition, the processing by the elements of each functional configuration described above can also be realized by a dedicated hardware circuit such as an ASIC (Application Specific Integrated Circuit). In this case, it may be executed by one hardware or a plurality of hardware.

A Image forming system A1 Image forming apparatus A2 Post-processing apparatus 1 Operation unit / display unit 1
2 Control unit 241 RIP unit 242 Spot color setting unit 243 Color conversion unit 3 Image forming unit 4 Paper feed unit 5 Color measurement unit 58 Sensors 9 and 9b Sample page

Claims (15)

It is determined whether or not a spot color is included in the print data. If a spot color is included, a spot color table in which spot color identification information and a printer device value indicating a density signal of a basic color are associated is used. A spot color setting unit for setting printer device values for spot colors,
An image forming unit that forms a color image on a recording medium based on a printer device value;
A colorimeter for measuring the color of an output image formed on a recording medium by the image forming unit and acquiring color information;
A color conversion unit that calculates a printer device value indicating a basic color density signal from color information;
Holding a colorimetric result of the colorimeter for an output image of a spot color as a history colorimetric result;
Determining whether the sample page creation condition is satisfied;
If it is determined that the sample page creation condition is satisfied, the first color sample image by the printer device value calculated on the basis of the features of the history colorimetry result, the by該特color printer device values determined from the spot color table Creating a sample page formed on a recording medium with two color sample images;
How to create a sample page with In the sample page,
2. The first color sample image includes the history color measurement result of a spot color and a color difference between the history color measurement result and the original color information of the spot color. How to create the sample page described. In the sample page:
For the second color sample image, estimated color information for the second color sample image and a color difference between the estimated color information and the original color information of the spot color are shown. A method for creating a sample page according to claim 1 or 2. In the step of holding the history color measurement result , the printer device value applied to the colorimetric output image is further held,
In the sample page,
Indicating the retained printer device value for the first color sample image;
4. The sample page creation according to claim 1, wherein a printer device value applied to the second color sample image is indicated for the second color sample image. Method. The color conversion unit includes a look-up table used when calculating a printer device value based on color information,
Performing the step of holding the history colorimetric result and then updating the lookup table before executing the step of creating the sample page;
5. The method according to claim 1, wherein in the step of creating the sample page, the color conversion unit determines a printer device value of the first color sample image using an updated lookup table. A method for creating the sample page according to any one of the above. Before executing the step of creating the sample page after executing the step of holding as the history color measurement result ,
A step of outputting a plurality of patch images having different printer device values for reproducing the history color measurement result, and acquiring a correspondence relationship between the printer device value and color information from the color measurement result of the output patch image; Have
5. The method according to claim 1, wherein in the step of creating the sample page, the color conversion unit determines a printer device value of the first color sample image from the acquired correspondence relationship. A method for creating the sample page described in one.   The sample page creation conditions are as follows: (1) Every time a predetermined number of prints are exceeded, (2) When the color difference between the original color information of the special color and the output image of the special color exceeds a predetermined value, (3) The historical color measurement The sample page creation method according to any one of claims 1 to 6, wherein the color difference between the result and the output image of the spot color exceeds a predetermined value. When executing one print job that includes spot color output,
The sample page creation conditions further target the same print job,
8. The sample page creation method according to claim 7, wherein the history color measurement result is a color measurement of an output image of the first spot color in the print job. In the step of holding as the history colorimetry result , the output condition of at least one of the print setting of printing and the ambient temperature and humidity at the time of printing is further held,
In the sample page:
The sample page creation method according to any one of claims 1 to 8, wherein the held output condition is indicated for the first color sample image.   The sample page according to any one of claims 1 to 9, wherein the original color information of the special color is outside a color gamut that can be reproduced by a color image formed on a recording medium by the image forming unit. How to make. It is determined whether or not a spot color is included in the print data. If a spot color is included, a spot color table in which spot color identification information and a printer device value indicating a density signal of a basic color are associated is used. A spot color setting unit for setting printer device values for spot colors,
An image forming unit that forms a color image on a recording medium based on a printer device value;
A colorimeter for measuring the color of an output image formed on a recording medium by the image forming unit and acquiring color information;
A color conversion unit that calculates a printer device value indicating a basic color density signal from color information;
A program that causes an image system to create a sample page,
Holding a colorimetric result of the colorimeter for an output image of a spot color as a history colorimetric result;
Determining whether the sample page creation condition is satisfied;
When it is determined that the sample page creation condition is satisfied, the first color sample image based on the printer device value calculated based on the historical color measurement result of the spot color and the spot color based on the printer device value of the spot color determined from the spot color table. Creating a sample page formed on a recording medium with two color sample images;
A program that causes a computer to run. In the sample page:
12. The history color measurement result of a spot color and a color difference between the history color measurement result and the original color information of the spot color are shown for the first color sample image. The listed program. It is determined whether or not a spot color is included in the print data. If a spot color is included, a spot color table in which spot color identification information and a printer device value indicating a density signal of a basic color are associated is used. A spot color setting unit for setting printer device values for spot colors,
An image forming unit that forms a color image on a recording medium based on a printer device value;
A colorimeter for measuring the color of an output image formed on a recording medium by the image forming unit and acquiring color information;
A color conversion unit that calculates a printer device value indicating a basic color density signal from color information;
A history holding unit that holds the color measurement result of the output image of the spot color as the history color measurement result;
Control means;
An image forming system comprising:
When it is determined that the sample page creation condition is satisfied, the control unit performs the first color sample based on the printer device value calculated by the color conversion unit based on the history color measurement result of the spot color held in the history holding unit. The image forming unit controls the image forming unit to form a sample page on which the image and the second color sample image based on the printer device value of the spot color determined from the spot color table are determined by the spot color setting unit. An image forming system. In the sample page,
14. The first color sample image includes the history color measurement result of a spot color and a color difference between the history color measurement result and the original color information of the spot color. Image forming system. With an operation display,
In the sample page, a plurality of color sample images having different printer device values in a plurality of stages are printed together with the second color sample image.
A correction unit capable of correcting the color of the spot color by a user inputting a printer device value or an identifier of the color sample shown in each of the plurality of color sample images from the operation display unit; The image forming system according to claim 13, wherein the image forming system is an image forming system.