JP5100014B2 - Color unevenness evaluation apparatus and evaluation method - Google Patents

Description

  The present invention relates to a color unevenness evaluation technique.

  It is important to evaluate color unevenness in a print area on a print medium. This is because if the color unevenness occurs, the print quality deteriorates.

  According to Patent Document 1, a method is proposed in which, on a print medium on which the same pattern is regularly printed, the coordinates of one pattern are determined based on the regularity of the pattern just by inputting the coordinates of one pattern. Has been.

According to Patent Document 2, an invention for performing spectrophotometry on a paper surface placed on an XY stage and obtaining a standard deviation, an average value, and a variation coefficient for tristimulus values X, Y, Z, Lab values, and WB values. Is described. Further, according to Patent Document 2, it is proposed to measure the surface sensation due to white unevenness or printing unevenness based on the fluctuation range of the spectral curve with respect to the standard deviation, the average value, and the variation coefficient.
JP-A-8-261829 JP-A-8-211988

  However, since the invention described in Patent Document 1 is based on the premise that the pattern is regularly arranged on the print medium, a large number of areas in which the pattern is not printed are generated in addition to the blank area. In this case, color unevenness or the like cannot be evaluated for a large number of non-printed areas.

  By the way, in order to investigate the cause of the occurrence of color unevenness due to the printed parts, it is desirable to compare the measurement data in consideration of the main scanning direction and the sub scanning direction in the printing apparatus. In general, rotating parts such as a photosensitive drum used in a printing apparatus perform periodic movement. Therefore, if there is an abnormality in the rotating component, periodic printing unevenness occurs in the main scanning direction or the sub-scanning direction.

  However, the invention described in Patent Document 2 does not evaluate color unevenness in consideration of the main scanning direction and the sub-scanning direction of a printing apparatus that performs printing on a printing medium. That is, it is difficult to find out the cause of color unevenness only by comparing one reference data such as an average value or standard deviation with all measured data.

  Accordingly, an object of the present invention is to provide a color unevenness evaluation technique that is useful for investigating the cause of occurrence of color unevenness.

The present invention is realized, for example, by an evaluation apparatus used for evaluating color unevenness on a recording medium on which an image is formed based on image signals of a single color and the same density by an image forming apparatus. The reading unit reads the measurement value of the spectral characteristic value of each measurement point that is two-dimensionally arranged according to the main scanning direction and the sub-scanning direction of the image forming apparatus. The determination means performs each measurement based on each spectral characteristic value of a series of measurement points arranged along the main scanning direction or the sub-scanning direction and a spectral characteristic value of a measurement point designated as a reference among the series of measurement points. Determine the color difference of a point. The output means outputs the color difference at each measurement point according to the position of each measurement point. The selection unit selects either the main scanning direction or the sub-scanning direction as a direction in which a series of measurement points that are targets for determining the color difference are arranged.

  According to the present invention, since color unevenness can be evaluated by acquiring a color difference between spectral characteristic values in accordance with the main scanning direction and the sub-scanning direction of the image forming apparatus, there is an advantage that it is useful for investigating the cause of occurrence of color unevenness.

  An embodiment of the present invention is shown below. Of course, the individual embodiments described below will be helpful in understanding various concepts such as the superordinate concept, intermediate concept and subordinate concept of the present invention. Further, the technical scope of the present invention is determined by the scope of the claims, and is not limited by the following individual embodiments.

[First Embodiment]
<Outline of measurement and evaluation system>
FIG. 1 is a diagram illustrating an example of a system for performing measurement and evaluation according to the embodiment. In this system, for example, color unevenness can be evaluated by measuring the spectral reflectance of an image formed on a recording medium. The system includes a measuring apparatus 100 that measures spectral reflectance, and a personal computer (PC) 150 that controls the measuring apparatus 100 and performs color evaluation.

  The measuring apparatus 100 is, for example, an automatic colorimeter. The PC 150 is an example of an information processing apparatus that uses the measurement apparatus 100. The image forming apparatus 180 can be realized as a printing apparatus, a printer, a copier, or a multifunction machine. The image forming apparatus 180 forms an image for evaluating color unevenness on a recording medium in accordance with an instruction from the PC 150. Note that the recording medium may be called a printing medium, a recording material, a sheet, a sheet, or a transfer material. In addition, the evaluation of color unevenness may be referred to as in-plane uniformity evaluation.

  The measuring apparatus 100 measures the spectral characteristic values of the measurement points that are two-dimensionally arranged according to the main scanning direction and the sub-scanning direction of the image forming apparatus 180. The measurement apparatus 100 includes a measurement table 101, rails 102 and 103 provided on the measurement table, a movable unit 104 that moves on the rail, and a spectrophotometer 105 that is attached to the movable unit. A recording medium 106 to be measured is placed on the measurement table 101. The measurement table 101 is sometimes called an XY table or an XY stage.

  The movable unit 104 moves in the horizontal direction (X direction) in the figure. The spectrophotometer 105 is moved in the vertical direction (Y direction) by the movable unit 104. That is, the spectrophotometer 105 can freely move on the XY coordinates. The movable unit 104 moves the spectrophotometer 105 to designated coordinates from the PC 150. The spectrophotometer 105 performs measurement at the coordinates.

  FIG. 2 is a block diagram illustrating an example of a control unit of the measurement apparatus according to the embodiment. The CPU 201 is a control unit that comprehensively controls each unit of the measuring apparatus 100 based on a computer program. The ROM 202 is a non-volatile storage unit that stores a computer program such as firmware. The RAM 203 is a volatile storage unit that functions as a work area. The display device 205 is a display unit for displaying various information to the user. The operation unit 206 is an input unit including, for example, up / down / left / right movement keys, a determination key, and a cancel key. Through the operation unit 206, the user can move the spectrophotometer 105 by manual operation.

  The communication interface 207 is a communication unit for communicating with the PC 150 such as a USB interface. Data measured by the spectrophotometer 105 is transferred to the PC 105 via the communication interface 207. The A / D converter 210 is a unit that converts an analog signal output from the spectrophotometer 105 into a digital signal. The drive control unit 211 controls the drive motor 212. The drive motor 212 is a motor for moving the movable unit 104 in the X-axis direction, a motor for moving the spectrophotometer 105 attached to the movable unit 104 in the Y-axis direction, or the like.

  FIG. 3 is a block diagram illustrating an example of a PC according to the embodiment. The CPU 301 is a control unit that comprehensively controls each unit of the PC 150 based on a computer program. For example, the CPU 301 determines each spectral characteristic value of a series of measurement points arranged in the main scanning direction or the sub-scanning direction and each spectral characteristic value of a measurement point designated as a reference among the series of measurement points. Determine the color difference of the measurement point. Further, for example, the CPU 301 outputs the color difference of each measurement point according to the position of each measurement point. The ROM 302 is a non-volatile storage unit that stores a computer program such as firmware. The RAM 303 is a volatile storage unit that functions as a work area. A hard disk drive (HDD) 304 is a large-capacity storage unit. The HDD 304 stores measurement data received from the measurement apparatus 100, measurement data evaluation programs, and the like.

  The display device 305 is a display unit for displaying various information to the user. For example, the display device 305 may output the color difference of each measurement point according to the position of each measurement point in accordance with an instruction from the CPU 301. The operation unit 306 is an input unit such as a pointing device or a keyboard. The communication interface 307 is a communication unit for communicating with the measurement apparatus 100 such as a USB interface.

  FIG. 4 is a diagram illustrating an example of a recording medium according to the embodiment. In this example, there is an image forming area 400 on which an image formed based on image signals of a single color and the same density is printed on the recording medium 106. Depending on the type of the image forming apparatus 180, there is an apparatus that cannot perform so-called borderless printing that forms an image over the entire surface of the recording medium. In this case, a blank area 401 is generated on the recording medium 106. In FIG. 4, the horizontal direction in the figure is the sub-scanning direction of the image forming apparatus 180. The vertical direction in the figure is the main scanning direction. Such direction definition is merely an example. That is, the vertical direction in the drawing may correspond to the sub-scanning direction.

  FIG. 5 is a flowchart illustrating an example of the color unevenness evaluation method according to the embodiment. It is assumed that the PC 150 functioning as the color unevenness evaluation apparatus performs image formation by the image forming apparatus 180 on the recording medium shown in FIG.

  In step S <b> 501, the CPU 301 of the PC 150 displays a measurement condition designation screen on the display device 305, and sets measurement conditions based on information input from the operation unit 306. For example, the division conditions (number of rows L and number of columns M) of the image forming area 400 are specified as part of the measurement conditions.

  FIG. 6 is a diagram illustrating an example of division of the image forming area according to the embodiment. In this example, N measurement areas are defined by dividing the image forming area 400 into L rows × M columns. The measurement point is, for example, the center of each measurement region.

  In step S502, the CPU 301 instructs the measurement apparatus 100 to perform measurement. At this time, the CPU 301 designates the coordinate data of each measurement point to the measurement apparatus 100. The CPU 201 of the measuring apparatus 100 moves the spectrophotometer 105 according to the coordinate data received from the CPU 301 and measures the spectral characteristic value at each measurement point. Further, the CPU 201 of the measurement apparatus 100 transmits the acquired spectral characteristic value of each measurement point to the PC 150. The CPU 301 of the PC 150 stores the received spectral characteristic value of each measurement point in the HDD 304 or the RAM 303.

  FIG. 7 is a diagram illustrating an outline of a measurement data set according to the embodiment. The measurement data set 700 includes measurement data 701, 720, 730 and property data 730. Each measurement data includes spectral characteristic value data 702 and information 703 of measurement positions (coordinate data of measurement points). The spectral characteristic value data 702 includes a spectral characteristic value in the visible range (380 nm to 730 nm) or absolute chromaticity (XYZ color system or L * a * b * color system) calculated from the spectral characteristic value. Concentration data can be included. The property data 730 includes information such as the name of the measurer, the measurement time, the observation light source, and the observation viewing angle.

  In step S <b> 503, the CPU 301 designates the reference according to the designation information input from the operation unit 306. Specifically, the CPU 301 displays a screen (window) for designating the evaluation direction on the display device 305. The evaluation direction means a direction in which measurement areas or measurement points to be evaluated are arranged. The evaluation direction is, for example, either the horizontal direction or the vertical direction of the image forming area 400 illustrated in FIG. Usually, the horizontal direction and the vertical direction correspond to either the main scanning direction or the sub-scanning direction of the image forming apparatus 180, respectively.

  FIG. 8 is a diagram illustrating an example of an evaluation direction designation screen according to the embodiment. The evaluation direction designation screen 800 is provided with a radio button 801 for designating the evaluation direction and a save button 802 for saving the designation result. The pointer 803 moves according to the operation of the pointing device of the operation unit 306. When a click operation is performed on the operation unit 306 in a state where the pointer 803 is positioned at the radio button 801, the evaluation direction is selected. Finally, when the save button 802 is clicked, the CPU 301 saves the specified evaluation direction information in the RAM 303 or the like. In this way, the CPU 301 has selected either the main scanning direction or the sub-scanning direction as the direction (evaluation direction) in which a series of measurement points serving as targets for determining the color difference are arranged.

  FIG. 9 and FIG. 10 are diagrams illustrating an example of a screen for designating a set of measurement data (reference data group) serving as a reference according to the embodiment. The screen 900 is provided with a map 901 imitating the image forming area 400, a pointer 902, a save button 903, a cancel button 904, and the like. In this example, the map 901 is divided into 5 rows × 7 columns. In this example, since the evaluation direction is designated in advance in the horizontal direction, a series of measurement data serving as a reference is each measurement data belonging to the designated column.

  When any column is clicked by the pointer 902, the screen 900 changes to the display state shown in FIG. The CPU 301 controls the display device 305 to highlight the clicked row. 1000 represents a highlighted column. Here, when the save button 903 is clicked, the CPU 301 saves identification information for identifying the selected row in the RAM 303. This identification information is, for example, “G” which is the identification information of the column.

  In this way, each of the five measurement data belonging to the G column becomes reference data in each row. That is, the CPU 301 designates a series of measurement points arranged in a direction different from the evaluation direction as a reference data group.

  In step S504, the CPU 301 determines the color difference of each measurement data. For example, when the horizontal direction is designated as the evaluation area, the CPU 301 sets each row as the evaluation area, and calculates a color difference for each evaluation area.

  FIG. 11 is a diagram for explaining a concept of a method for determining a color difference according to the embodiment. According to FIG. 11, a series of measurement data arranged in the horizontal direction in each row constitutes an evaluation region. That is, each row from the first row to the fifth row forms one evaluation region. The CPU 301 compares each measurement data from the A column to the G column in each row with the measurement data in the G column designated as a reference.

  FIG. 12 is a flowchart illustrating an example of a method for determining a color difference according to the embodiment. This flowchart is a subroutine of step S504 described above. In step S <b> 1201, the CPU 301 reads evaluation direction information from the RAM 303. In step S <b> 1202, the CPU 301 extracts a measurement data group forming one evaluation area from the measurement data set 700 in accordance with the read evaluation direction information. For example, for the evaluation area 1, all measurement data in the first row is read from the HDD 304.

  In step S1203, the CPU 301 reads reference designation information from the RAM 303, and extracts measurement data (reference data) serving as a reference in accordance with the read designation information. For example, the measurement data of the designated G column in the measurement data group that forms one evaluation area is read from the HDD 304.

  In step S1204, the CPU 301 calculates a color difference based on target measurement data and reference data. For example, the color difference value (ΔE) between the reference data and the measurement data can be calculated as follows. Here, an example in which absolute chromaticity (L * a * b *) is employed as measurement data will be described.

_Let the absolute chromaticity of the reference be L _r *, a _r *, b _r *. Also, let the absolute chromaticity of the i-th target be L _i *, a _i *, b _i *. In this case, the i-th color difference (ΔE) can be calculated from the following equation. Note that the calculated color difference data is stored in the HDD 304.

ΔL _i * = L _r * −L _i *
Δa _i * = a _r * −a _i *
Δb _i * = b _r * −b _i *

  In step S1205, the CPU 301 determines whether or not measurement data for which calculation of color difference has not been completed remains in the current evaluation region. If it remains, the process returns to step S1204, and the color difference is calculated for the next measurement data. If not, the process advances to step S1206, and the CPU 301 determines whether there is a remaining evaluation area. If the determination of the color difference has been completed for all the evaluation areas, this process is terminated. If the evaluation area remains, the process returns to step S1202.

  Returning to the description of FIG. In step S <b> 505, the CPU 301 statistically processes the determined color difference data in order to easily evaluate color unevenness. For example, the CPU 301 calculates an average value of color differences, a maximum value of color differences, and the like for each evaluation area.

  In step S506, the CPU 301 outputs the result of statistical processing from the display device 305 in order to perform color evaluation.

  FIG. 13 is a diagram illustrating an example of an evaluation screen according to the embodiment. The exemplary evaluation screen 1300 includes an area 1301 for displaying measurement results, an area 1302 for displaying properties of measurement data, an area 1303 for displaying statistical processing results, and the like.

  In the area 1301 for displaying the measurement result, each measurement point is displayed as a rectangle, and a color difference value is displayed in each rectangle. The position of each measurement point corresponds to the actual position in the image forming area.

  In addition, in order to divide each color difference into levels, rectangular display colors may be made different. According to FIG. 13, for color differences of 0.0 or more and less than 0.3, a rectangle is displayed in the first color. For color differences of 0.3 or more and less than 1.0, a rectangle is displayed in the second color. For color differences of 1.0 or more and less than 1.6, a rectangle is displayed in the third color. Thereby, it will be possible to visually recognize the color difference. Of course, each threshold for color coding is merely an example.

  Moreover, in order to make each evaluation area easy to understand visually, the CPU 301 may display an individual rectangular frame 1304 for each evaluation area. Further, the CPU 301 may display the reference data group surrounded by a rectangular frame 1305 so that the reference data group can be easily understood visually. It should be noted that it is desirable that the rectangular frame 1304 and the rectangular frame 1305 be displayed visually differentiated, for example, by making the colors of the frames different.

  FIG. 14 is a diagram illustrating another example of the evaluation screen according to the embodiment. In this example, an area 1401 is adopted instead of the area 1301 for displaying the measurement result. In a region 1401, changes in color difference for each evaluation region are displayed as a line graph. An area 1402 is a display area for indicating whether or not the in-plane uniformity (color unevenness) has reached the acceptance standard.

  In step S507, the CPU 301 performs color unevenness evaluation based on the color difference data. For example, the CPU 301 compares the color difference data with a reference value to determine whether or not the color unevenness reaches the acceptance standard.

  FIG. 15 is a diagram illustrating an example of a screen for setting a reference value for pass or fail of color unevenness according to the embodiment. In this example, it is indicated that the in-plane uniformity is rejected when 10 or more pieces of measurement data having a color difference of 0.30 or more and less than 1.00 are present. Further, it is shown that the in-plane uniformity is rejected when there are seven or more pieces of measurement data having a color difference of 1.00 or more and less than 1.60. If the maximum value of the color difference is 2.00 or more, the in-plane uniformity is similarly rejected. Furthermore, it is shown that the in-plane uniformity is rejected when the average value of the color difference is 1.60 or more. In this way, a reference value for in-plane uniformity (color unevenness) is set.

  As described above, according to the present embodiment, the CPU 301 obtains each spectral characteristic value of a series of measurement points arranged in the main scanning direction or the sub scanning direction of the image forming apparatus. Further, the CPU 301 determines the color difference of each measurement point based on each obtained spectral characteristic value and the spectral characteristic value of the measurement point designated as a reference among the series of measurement points.

  For example, as shown in FIG. 11, the color difference based on each of the seven measurement data in the first row arranged in the sub-scanning direction and the measurement data in the G column designated as the reference in the first row. Is determined. If the cause of color unevenness is in the rotating part of the image forming apparatus, periodic color unevenness occurs in the main operation direction or the sub-scanning direction. Therefore, as in the color unevenness evaluation technique according to this embodiment, the cause of color unevenness can be easily determined by setting the evaluation direction to the main operation direction or the sub-scanning direction.

  Further, as shown in FIG. 8, the evaluator uses the operation unit 306 in the main scanning direction or the sub-scanning direction as a direction (evaluation direction) in which a series of measurement points serving as targets for determining the color difference are arranged. Either can be selected. Therefore, the evaluator can easily select a direction in which evaluation is desired, that is, a direction useful for investigating the cause of occurrence of color unevenness.

  Also, as shown in FIGS. 9 and 10, in this embodiment, a series of measurement points arranged in a direction different from the direction in which the series of measurement points are arranged can be designated as a reference data group. In other words, if the evaluation direction is the horizontal direction, the evaluator can set the reference data group simply by designating any one column, so that the designation operation will be simplified.

  Further, as illustrated in FIGS. 13 to 15, the CPU 301 can determine whether or not the image formed on the recording medium or the color unevenness of the image forming apparatus is acceptable based on a plurality of color differences. Will be greatly reduced.

[Second Embodiment]
In the above-described embodiment, the image forming area is divided into measurement areas of L rows × M columns, and measurement data is acquired using the center of each measurement area as a measurement point. All measurement data was used. However, depending on the evaluation method, it is not always necessary to acquire color differences for all measurement data. For example, there may be cases where it is sufficient to obtain the color difference for each specific evaluation period. Therefore, in the present embodiment, a method for evaluating color unevenness by designating an evaluation cycle will be described.

  FIG. 16 is a diagram for explaining a concept of a method for determining a color difference according to the embodiment. In this example, the evaluation period is set in three columns. Therefore, the targets for determining the color difference are the data in the A column and the data in the D column.

  Note that when the value of the evaluation period can be freely input, there may be a case where there is no measurement data of coordinates corresponding to the designated evaluation period. In this case, the color difference cannot be determined, which is inconvenient. Therefore, a fixed (error) range may be considered from the coordinates corresponding to the designated evaluation cycle. If the measurement point is included in such a range, the color difference can be determined using the measurement data of the measurement point, which is convenient.

  FIG. 17 is a diagram illustrating an example of an evaluation direction and evaluation period designation screen according to the embodiment. In addition, description is simplified by attaching | subjecting the same referential mark to the already demonstrated location. The designation screen 1700 is provided with a text box 1701 for designating an evaluation cycle. An evaluation period value is input to the text box 1701 through the operation unit 306.

  FIG. 18 is a flowchart illustrating an example of the reference designating process according to the embodiment. Note that this flowchart is a subroutine of step S503 described above.

  In step S <b> 1801, the CPU 301 displays a designation screen 1700 on the display device 305 and designates an evaluation method and an evaluation cycle according to information input through the operation unit 306. Information on the designated evaluation method and information on the evaluation cycle are stored in the RAM 303.

  In step S <b> 1802, the CPU 301 displays a designation screen 900 on the display device 305 and designates a reference row or column according to information input through the operation unit 306. Information on the designated reference is stored in the RAM 303.

  In step S <b> 1803, the CPU 301 calculates coordinate data that matches the evaluation cycle from the measurement point that is the designated reference. That is, this coordinate data becomes the coordinate data of the target measurement point.

  In step S1804, the CPU 301 determines whether there is a measurement point (target) having the calculated coordinate data based on the information 703 regarding the measurement position. Note that, as described above, it is expected that the coordinates of the target calculated from the coordinates of the reference measurement point and the evaluation period do not completely match the coordinates of any of the measurement points. Therefore, a certain error range is set in the coordinates of the target, and if any measurement point is included in the error range, the CPU 301 may extract the measurement point as a target.

  If the result of determination is that there is a target, this processing is terminated. On the other hand, if the target does not exist, the process returns to step S1805, and the CPU 301 displays a message indicating that the target does not exist on the display device 305. After that, the process returns to step S1802, and the CPU 301 executes the reference designation process again. Note that the CPU 301 may change the evaluation period by returning to step S1801 instead of step S1802.

  FIG. 19 is a flowchart illustrating an example of the color difference test process according to the embodiment. In addition, description is simplified by attaching | subjecting the same referential mark to the already demonstrated location. In the flowchart shown in FIG. 12, the color difference is calculated in order for all the measurement data included in the evaluation region. However, in this flowchart, the color difference is calculated for the measurement data at the measurement point that matches the evaluation cycle.

  In step S1901, the CPU 301 reads evaluation period information from the RAM 303. In step S1902, target measurement data is extracted according to the evaluation period. Specifically, the CPU 301 determines a measurement point by a process equivalent to the process described in step S1803, and reads measurement data of the determined measurement point from the HDD 304. Thereafter, the color difference is determined for the measurement data of the target that matches the evaluation cycle, and the color unevenness evaluation process is executed (S1204 to S1206).

  According to the present embodiment, the periodic in-plane uniformity is determined by determining the color difference using measurement data of measurement points arranged at a constant interval (evaluation period) in the main scanning direction or the sub-scanning direction. Evaluation can be performed. This makes it possible to periodically evaluate the components of the image forming apparatus (such as a drum of a printing machine).

  In the above embodiment, the image forming apparatus such as a printing apparatus has been described as an example. However, from the viewpoint of evaluating color unevenness, the present invention is also applicable to evaluation of color unevenness on the screen of an image display device such as a display. it can. In this case, the recording medium may be considered as a display panel of the display device. Note that the image forming apparatus and the image display apparatus are subordinate concepts of the image output apparatus.

[Other Embodiments]
Although various embodiments have been described in detail above, the present invention may be applied to a system constituted by a plurality of devices, or may be applied to an apparatus constituted by one device. For example, a scanner, a printer, a PC, a copier, a multifunction machine, and a facsimile machine.

  The present invention supplies a software program that implements the functions of the above-described embodiments directly or remotely to a system or apparatus, and a computer included in the system reads and executes the supplied program code. Can also be achieved.

  Accordingly, since the functions and processes of the present invention are implemented by a computer, the program code itself installed in the computer also implements the present invention. That is, the computer program itself for realizing the functions and processes is also one aspect of the present invention.

  In this case, the program may be in any form as long as it has a program function, such as an object code, a program executed by an interpreter, or script data supplied to the OS.

  Examples of the recording medium for supplying the program include a flexible disk, hard disk, optical disk, magneto-optical disk, MO, CD-ROM, CD-R, and CD-RW. Examples of the recording medium include a magnetic tape, a non-volatile memory card, a ROM, a DVD (DVD-ROM, DVD-R), and the like.

  The program may be downloaded from a homepage on the Internet using a browser on a client computer. That is, the computer program itself of the present invention or a compressed file including an automatic installation function may be downloaded from the home page to a recording medium such as a hard disk. It can also be realized by dividing the program code constituting the program of the present invention into a plurality of files and downloading each file from a different homepage. That is, a WWW server that allows a plurality of users to download a program file for realizing the functional processing of the present invention on a computer may be a constituent requirement of the present invention.

  Further, the program of the present invention may be encrypted and stored in a storage medium such as a CD-ROM and distributed to users. In this case, only users who have cleared the predetermined conditions are allowed to download the key information for decryption from the homepage via the Internet, decrypt the program encrypted with the key information, execute it, and install the program on the computer. May be.

  Further, the functions of the above-described embodiments may be realized by the computer executing the read program. Note that an OS or the like running on the computer may perform part or all of the actual processing based on the instructions of the program. Of course, also in this case, the functions of the above-described embodiments can be realized.

  Furthermore, the program read from the recording medium may be written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Based on the instructions of the program, a CPU or the like provided in the function expansion board or function expansion unit may perform part or all of the actual processing. In this way, the functions of the above-described embodiments may be realized.

It is a figure which shows an example of the system for performing the measurement and evaluation which concern on embodiment. It is a block diagram which shows an example of the control part of the measuring device which concerns on embodiment. It is a block diagram which shows an example of PC concerning embodiment. It is a figure which shows an example of the recording medium which concerns on embodiment. It is a flowchart which shows an example of the color nonuniformity evaluation method which concerns on embodiment. It is a figure which shows the example of a division | segmentation of the image formation area which concerns on embodiment. It is a figure which shows the outline | summary of the measurement data set which concerns on embodiment. It is a figure which shows an example of the designation | designated screen of the evaluation direction which concerns on embodiment. It is a figure which shows an example of the screen for designating the measurement data group used as the reference which concerns on embodiment. It is a figure which shows an example of the screen for designating the measurement data group used as the reference which concerns on embodiment. It is a figure for demonstrating the concept of the method of determining the color difference which concerns on embodiment. It is a flowchart which shows an example of the method of determining the color difference which concerns on embodiment. It is a figure which shows an example of the evaluation screen which concerns on embodiment. It is a figure which shows the other example of the evaluation screen which concerns on embodiment. It is a figure which shows the screen for setting the acceptance | permission reference value of in-plane uniformity which concerns on embodiment. It is a figure for demonstrating the concept of the method of determining the color difference which concerns on embodiment. It is a figure which shows an example of the designation | designated screen of the evaluation direction and evaluation period which concern on embodiment. It is a flowchart which shows an example of the reference designation | designated process which concerns on embodiment. It is a flowchart which shows an example of the color difference test process which concerns on embodiment.

Claims (9)

An evaluation method for evaluating color unevenness on a recording medium on which an image is formed based on an image signal of a single color and the same density by an image forming apparatus,
A reading step of reading the spectral characteristic value of each measurement point two-dimensionally arranged according to the main scanning direction and the sub-scanning direction of the image forming apparatus as a measurement value;
Each measurement point based on each spectral characteristic value of a series of measurement points arranged along the main scanning direction or the sub-scanning direction and a spectral characteristic value of a measurement point designated as a reference among the series of measurement points A determination step for determining the color difference of
Including an output step of outputting the color difference of each measurement point according to the position of each measurement point ,
The evaluation method further comprising a selection step of selecting either the main scanning direction or the sub-scanning direction as a direction in which the series of measurement points that are targets for determining the color difference are arranged . The evaluation method according to claim 1 , further comprising a designation step of designating a series of measurement points arranged in a direction different from a direction in which the series of measurement points are arranged as a reference data group. The evaluation method according to claim 1 , further comprising a determination step of determining pass / fail regarding an image formed on the recording medium or color unevenness of the image forming apparatus based on a plurality of the color differences. The determination step extracts measurement data of measurement points arranged at regular intervals in the direction selected by the selection step in the main scanning direction or the sub-scanning direction from the series of measurement points. evaluation method according to any one of claims 1 to 3, characterized in that for the said measured data is a step of determining the color difference. An evaluation apparatus used when evaluating color unevenness on a recording medium on which an image is formed based on an image signal of a single color and the same density by an image forming apparatus,
Reading means for reading the spectral characteristic values of the measurement points two-dimensionally arranged according to the main scanning direction and the sub-scanning direction of the image forming apparatus as measurement values;
Spectral characteristic values of a series of measurement points arranged along the main scanning direction or the sub-scanning direction, and spectral characteristic values of measurement points designated as a reference among a series of measurement points read by the reading unit; Determining means for determining the color difference of each measurement point based on
Output means for outputting the color difference of each measurement point according to the position of each measurement point ,
The evaluation apparatus further comprising selection means for selecting either the main scanning direction or the sub-scanning direction as the direction in which the series of measurement points that are targets for determining the color difference are arranged . A computer program used for evaluating color unevenness on a recording medium on which an image is formed based on image signals of a single color and the same density by an image forming apparatus,
A reading step of reading, as a measurement value, a spectral characteristic value of each measurement point that is two-dimensionally arranged according to a main scanning direction and a sub-scanning direction of the image forming apparatus,
Each measurement point based on each spectral characteristic value of a series of measurement points arranged along the main scanning direction or the sub-scanning direction and a spectral characteristic value of a measurement point designated as a reference among the series of measurement points A determination step for determining the color difference of
The output means causes the computer to execute an output step of outputting the color difference of each measurement point according to the position of each measurement point , and further,
Causing a computer to execute a selection step of selecting either the main scanning direction or the sub-scanning direction as a direction in which the series of measurement points serving as targets for determining the color difference is arranged by a selection unit; Computer program. An evaluation method for evaluating color unevenness for a single color and the same density image output by an image output device,
A reading step of reading the spectral characteristic value of each measurement point two-dimensionally arranged according to the main scanning direction and the sub-scanning direction of the image output device as a measurement value;
Each measurement point based on each spectral characteristic value of a series of measurement points arranged along the main scanning direction or the sub-scanning direction and a spectral characteristic value of a measurement point designated as a reference among the series of measurement points A determination step for determining the color difference of
Including an output step of outputting the color difference of each measurement point according to the position of each measurement point ,
The evaluation method further comprising a selection step of selecting either the main scanning direction or the sub-scanning direction as a direction in which the series of measurement points that are targets for determining the color difference are arranged . An evaluation device for evaluating color unevenness for a single color and same density image output by an image output device,
Reading means for reading the spectral characteristic values of the respective measurement points two-dimensionally arranged according to the main scanning direction and the sub-scanning direction of the image output device as measurement values;
Each measurement point based on each spectral characteristic value of a series of measurement points arranged along the main scanning direction or the sub-scanning direction and a spectral characteristic value of a measurement point designated as a reference among the series of measurement points Determining means for determining the color difference of
Output means for outputting the color difference of each measurement point according to the position of each measurement point ,
The evaluation apparatus further comprising selection means for selecting either the main scanning direction or the sub-scanning direction as the direction in which the series of measurement points that are targets for determining the color difference are arranged . A computer program used to evaluate color unevenness for a single color and same density image output by an image output device,
A reading step of reading the spectral characteristic value of each measurement point two-dimensionally arranged according to the main scanning direction and the sub-scanning direction of the image output device as a measurement value;
Each measurement point based on each spectral characteristic value of a series of measurement points arranged along the main scanning direction or the sub-scanning direction and a spectral characteristic value of a measurement point designated as a reference among the series of measurement points A determination step for determining the color difference of
And causing the computer to execute an output step of outputting the color difference of each measurement point according to the position of each measurement point ,
Causing a computer to execute a selection step of selecting either the main scanning direction or the sub-scanning direction as a direction in which the series of measurement points serving as targets for determining the color difference is arranged by a selection unit; Computer program.

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