JP4255018B2 - How to calibrate multiple color monitors - Google Patents

Description

  The present invention relates to a color monitor calibration method for adjusting color reproduction and gradation reproduction characteristics of a color monitor to a desired state when performing color management using the color monitor, and more particularly to a plurality of color monitors. The present invention relates to a method for calibrating white and gradation reproduction characteristics to the same state while reflecting the influence of ambient light including illumination light.

  First, a color monitor is defined prior to explanation. In this specification, “color monitor” refers to all display devices that perform color reproduction by additive color mixing of the three primary colors R (red), G (green), and B (blue). Typical examples include a color CRT, a color liquid crystal display device, and a color plasma display display device.

  In recent years, grasp the characteristics of input devices such as scanners and digital cameras, display devices such as color monitors, output devices such as printers and printing machines, describe the characteristics in a file, and perform color conversion using the characteristics file Accordingly, a technique called color management for matching the colors of various devices is generally performed. In color management of a color monitor, calibration is performed to make the characteristics of the color monitor desired characteristics.

  There are two types of calibration for the color monitor: white color adjustment and tone reproduction characteristic adjustment. Here, the adjustment of the white color is to adjust the white color displayed on the color monitor to a desired color. Note that white is an achromatic color and has only luminance and no saturation, but in many cases, white actually displayed on a color monitor also has saturation. That is, as is well known, when the RGB color is maximized on the color monitor, it is white, but even if R, G and / or B are slightly changed from that state, The color will be recognized as white. In this way, white displayed on a color monitor has not only brightness but also saturation, and this difference in brightness and chromaticity appears as a difference in white color. It is necessary.

  The adjustment of the gradation reproduction characteristic is an adjustment for making the gradation reproduction characteristic representing the relationship between the gradation value of the input signal and the luminance actually displayed on the color monitor a desired characteristic. Sometimes referred to as correction. When calibrating the gradation reproduction characteristics, as is conventionally performed, and as described later, the three primary colors in which the gradation value is changed for each of the primary colors of gray scale and RGB are variously changed. Step chart color measurement is required.

  As described above, the calibration of the white color of the color monitor requires the measurement of the reference white and the white displayed on the color monitor screen, and the calibration of the gradation reproduction characteristics. Needs to measure the gray scale displayed on the color monitor.

  There are two methods for performing such measurement: a visual method and a method using a colorimeter. Further, a method using a contact colorimeter is used as a method using a colorimeter. And a method using a non-contact colorimeter.

For example, Patent Literature 1, Patent Literature 2, Patent Literature 3, and Patent Literature 4 are methods or apparatuses for visually calibrating gradation reproduction characteristics. For example, Patent Document 1 discloses that gradation reproduction characteristics are calibrated by visually matching a dither image and a continuous tone image, and Patent Document 4 discloses a color monitor by visual inspection. It is disclosed that calibration of the tone reproduction characteristics is performed. There are also commercially available tools for performing various colorimetry visually or using a colorimeter and calibrating a color monitor. It should be noted that the applicant previously filed an application (Japanese Patent Application No. 2003-170623) regarding an apparatus for calibrating gradation reproduction characteristics by visual observation.
Japanese Patent No. 2889078 JP-A-7-162714 Japanese Patent Application Laid-Open No. 8-194442 JP 11-338443 A

  Incidentally, in a department that performs color management, a plurality of color monitors are usually arranged. For example, as one of the color management, there is a so-called soft proof in which a color image is displayed on a color monitor before the actual printing is verified, and so-called soft proof is called. A plurality of color monitors are arranged, and color images are displayed on these color monitors to confirm the completion of printing. In such a case, it is desired that the color reproduction and gradation reproduction characteristics of the plurality of color monitors are all adjusted to the same state. This is because soft proofing cannot be performed if the color of the display image differs depending on the color monitor.

  Thus, when arranging a plurality of color monitors, it is desired to calibrate all the color monitors to the same state. In the calibration of each color monitor, when a contact colorimeter is used as a means for measuring white and gradation reproduction characteristics, the measurement can be performed stably. It is possible to stably match the color tone and tone reproduction characteristics.

  However, when a contact-type colorimeter is used, the colorimetric value does not reflect the influence of the ambient light, so that the calibration result does not reflect the influence of the ambient light. It is important to reflect the influence of ambient light on the calibration result of the color monitor. This is because the observation of the printed matter and the image displayed on the color monitor during the soft proof are usually performed under a predetermined ambient light.

  In contrast, when a non-contact colorimeter is used as a measurement means during calibration, there is an advantage that the influence of ambient light can be reflected in the calibration result. The colorimeter has a drawback that the measurement is very laborious due to severe setup conditions such as the colorimetric value changes depending on the angle at which the colorimeter is installed. In particular, when a non-contact type colorimeter is used for a plurality of color monitors, the measurement effort is enormous.

  In addition, when calibration is performed visually, there is an advantage that the influence of ambient light can be reflected in the calibration result, but since there are individual differences in visual measurement, calibration is performed by multiple people. However, there is a drawback that the variation of the calibration result becomes large. Even if a plurality of color monitors are calibrated alone, the measurement is not stable, and the variation in the calibration result becomes larger than when the colorimeter is used.

  Therefore, the present invention can calibrate a plurality of color monitors to the same state while reflecting the influence of ambient light, and can reduce the time and effort required for measurement to a minimum. An object of the present invention is to provide a calibration method.

In order to achieve the above object, a calibration method for a plurality of color monitors according to the present invention selects one reference color monitor as a reference from the plurality of color monitors, and the white color of the selected reference color monitor is selected. The color tone calibration is performed visually or using a non-contact colorimeter as the measurement means, and the gradation reproduction characteristic calibration is performed using the contact colorimeter as the measurement means. In addition, the color reproduction characteristics are measured using a contact-type colorimeter, and the calibration of color monitors other than the reference color monitor is measured using the white value and gradation reproduction characteristics measured for the reference color monitor as target values. It is characterized by using a contact-type colorimeter as a means.

In the calibration method for a plurality of color monitors according to the present invention , one reference color monitor as a reference is selected from the plurality of color monitors, and white color calibration of the selected reference color monitor is performed by a measuring unit. As a measurement method, the calibration of gradation reproduction characteristics is performed using a contact colorimeter as a measuring means, and the white and gradation reproduction characteristics after calibration are measured using contact-type colorimetry. A color monitor is used to calibrate a color monitor other than the reference color monitor. A white color value and gradation reproduction characteristics measured for the reference color monitor are used as target values, and a contact color meter is used as a measuring means. Therefore, all color monitors should be calibrated stably, reflecting the effects of ambient light and with the minimum amount of effort required. Bets can be particularly effective when used to attach a monitor hood on the color monitor.

  Hereinafter, embodiments of the invention will be described with reference to the drawings. Now, assume that a plurality of color monitors are arranged. FIG. 1 shows an example of this state. In FIG. 1, two color monitors 104 and 204 are arranged. Naturally, a larger number of color monitors may be arranged, but here, a case where there are two color monitors will be described.

  The color monitor 104 is connected to a computer system 100 for capturing image data from the outside and displaying the image, and for performing calibration processing and profile creation processing. That is, the computer system 100 incorporates software for capturing and displaying image data and software for performing calibration and profile creation.

  The computer system 100 includes main control means 101 for capturing and displaying image data, calibrating the color monitor 104, and creating a profile for the color monitor 104, and input means 102 including an input device such as a keyboard and a mouse. In addition, the colorimeter 103 can be connected.

  Similarly, a computer system 200 is connected to the color monitor 204 for capturing image data from the outside and displaying the image, and for performing calibration processing and profile creation processing. That is, the computer system 200 incorporates software for capturing and displaying image data and software for performing calibration and profile creation.

  The computer system 200 includes a main control unit 201 that captures and displays image data, calibrates the color monitor 204, and creates a profile for the color monitor 204, and an input unit 202 including an input device such as a keyboard and a mouse. In addition, the colorimeter 203 can be connected.

  Here, as the color monitors 104 and 204, as described above, the color CRT, the color liquid crystal display measurement / adjustment device, the color plasma display display measurement / adjustment device, etc. Any device that reproduces color by additive color mixing may be used. Each computer system and the corresponding color monitor are connected by a VGA cable, a DVI cable, a BNC cable, or the like via a video card built in the computer system. The video card will be described later.

  As the colorimeters 103 and 203, a contact colorimeter or a non-contact colorimeter is used. Any of them can be connected to the main control unit 101 of the computer system 100 and the main control unit 201 of the computer system 200 and can be controlled by the main control unit 101 or the main control unit 201. Colorimeters that can be controlled by such control means are widely known. The connection between the main control unit 101 and the colorimeter 103 and the connection between the main control unit 201 and the colorimeter 203 can be performed by a serial method, a USB method, IEEE1394, or any other appropriate method. .

  Although the color measuring device is well known, the non-contact type color measuring device is a color measuring device capable of measuring the color of both a light emitting body such as a color monitor and a reflecting object such as a printed matter and a tile in a non-contact manner. There are luminance meter and color meter. The contact-type colorimeter is a colorimeter that performs color measurement by contacting a measurement object. In FIG. 1, only one colorimeter is connected to the main control means 101, 201, but two types of colorimeters, a contact colorimeter and a non-contact colorimeter, may be connected. Needless to say.

First, a reference example of a calibration method for a plurality of color monitors according to the present invention will be described. FIG. 2 is a flowchart showing a reference example of a calibration method for a plurality of color monitors according to the present invention. First, one color monitor is selected from the plurality of color monitors (step S1). Here, the color monitor selected in step S1 is referred to as a reference color monitor. Here, it is assumed that the color monitor 104 of FIG. 1 is selected as the reference color monitor.

  Next, the reference color monitor 104 selected in step S1 is calibrated reflecting the influence of ambient light (step S2). That is, in this case, either a visual or non-contact colorimeter is used as a measuring means for performing two calibrations of white color tone and gradation reproduction characteristics. This calibration is executed by the computer system 100.

  The processing at this time will be described later. In visual inspection, white color calibration is performed by comparing a reference white object having a reference white prepared in advance by an operator with white displayed on the reference color monitor 104. The white displayed on the reference color monitor 104 is matched with the white of the reference white object. Further, the gradation reproduction characteristic calibration is performed by setting a target gradation reproduction characteristic in advance and observing a predetermined image pattern displayed on the reference color monitor 104 while the operator is in a gray or three primary color state. Based on this, the computer system 100 sets the gradation reproduction characteristics to a target state.

  When the non-contact colorimeter is used, the white color calibration is displayed on the reference color monitor 104 by the computer system 100 and the reference color monitor 104 having a reference white color having a reference white prepared in advance. The white color displayed on the reference color monitor 104 is adjusted to match the white of the reference white object while comparing the colorimetric values of the white. At this time, the finally set white is measured and the colorimetric value is stored. Further, the gradation reproduction characteristics are calibrated by measuring a predetermined image pattern displayed on the reference color monitor 104 by the computer system 100 using a non-contact colorimeter, and determining the internal state of the computer system 100 or the reference color monitor. The internal state of 104 is adjusted so as to have a preset target tone reproduction characteristic.

  In this way, the calibration of the reference color monitor 104 is performed, and it is clear that the influence of ambient light is reflected in the result of this calibration.

  Next, a profile is created for the reference color monitor 104 in practice. However, since profile creation is not an essential matter in the present invention, illustration is omitted in FIG. As will be described later, it is necessary to measure the chromaticity of the three primary colors of RGB at the time of creating the profile. As the measuring means, it is preferable to use a contact-type colorimeter in order to perform measurement stably.

  When the calibration and profile creation for the reference color monitor 104 are completed, the contact-type colorimeter is used to measure the white and gradation reproduction characteristics set by the calibration, and the colorimetric values are obtained. Save (step S3). At this time, the contact type colorimeter is used because the measurement can be performed easily and stably. The process at this time will be described later.

  Next, the color monitor other than the reference color monitor 104, in the case of FIG. 1, the color monitor 204 is calibrated using a contact colorimeter as a measuring means (step S4). Both the white color tone and the tone reproduction characteristics are calibrated by using a contact colorimeter. That is, the influence of ambient light is not reflected in the calibration of color monitors other than the reference color monitor. As the target values of white and gradation reproduction characteristics in the calibration at this time, the measured values of white and gradation reproduction characteristics set in the calibration of the reference color monitor 104 measured in step S3 are used. This calibration is executed by the computer system 200.

  Although processing at this time will be described later, white color calibration is performed by the computer system 200 using a white colorimetric value set by calibration of the reference color monitor 104 as a target value. White displayed on the color monitor 204 is measured with a contact-type colorimeter, and adjusted so as to coincide with the target white value. In addition, the calibration of the gradation reproduction characteristic is displayed on the color monitor 204 other than the reference color monitor by the computer system 200 using the measured value of the gradation reproduction characteristic set by the calibration of the reference color monitor 104 as a target value. A predetermined image pattern is measured with a contact-type colorimeter, and the internal state of the computer system 200 or the state of the color monitor 204 is adjusted so as to match the target tone reproduction characteristics.

  Next, in practice, a profile is created for the color monitors 204 other than the reference color monitor 104, but the profile creation is not an essential matter in the present invention, and is not shown in FIG. A contact-type colorimeter may be used as the measuring means at this time.

As described above, in the reference example of the calibration method for a plurality of color monitors according to the present invention, the calibration of the reference color monitor reflects the influence of ambient light using a visual or non-contact colorimeter. The color monitor other than the reference color monitor is calibrated by measuring the white value set in the calibration of the reference color monitor and the tone reproduction characteristics using a contact colorimeter as a target value. As a result, calibration of all color monitors can be performed stably with the minimum necessary effort reflecting the influence of ambient light.

  When calibrating the reference color monitor, a visual or non-contact colorimeter is used, but only one of the reference color monitors is calibrated using the non-contact color meter. The time and effort required for this can be minimized. Also, when the reference color monitor is calibrated visually, only one reference color monitor is calibrated visually, so there is no variation. Calibration of color monitors other than the reference color monitor is performed using a contact-type colorimeter, so that there is no variation and can be performed stably.

Next, an embodiment of a calibration method for a plurality of color monitors according to the present invention will be described. This embodiment is described above only in that a contact-type colorimeter is used as a measurement means when performing gradation reproduction characteristic calibration among the calibration of the reference color monitor in step S2 of FIG. It is different from the reference example . That is, among the calibrations of the reference color monitor, white color calibration is performed visually or using a non-contact colorimeter, but gradation reproduction characteristics are calibrated using a contact color meter. is there.

  The meaning of this is as follows. As will be described later, when calibrating the white color of the reference color monitor, a reference white object having a desired white to be used as a reference is prepared, and the reference white object is displayed on the reference color monitor. In that case, the white of the reference white object will change accordingly if the ambient light hitting the reference white object changes. Therefore, in order to reflect the influence of such ambient light on the calibration of the white color of the reference color monitor, it is necessary to visually or use a non-contact colorimeter as the measuring means.

  Of course, ambient light also appears on the screen of the reference color monitor, and as a result, the color and tone reproduction characteristics of the reference color monitor itself may change. However, a monitor hood is often attached to the color monitor. In this case, the ambient light is less reflected on the screen of the color monitor, and the influence of the ambient light is reduced. Therefore, when calibrating the gradation reproduction characteristics, a contact-type colorimeter can be used as a measuring means. There is no problem and it is an effective method.

Thus, when a color monitor on the monitor hood is attached is than when calibration of the tone reproduction characteristics of the reference color monitor is also effective with a contact colorimeter as measuring means, which is the This is an embodiment. Therefore, according to this embodiment, the same effects as those of the reference example described above are obtained except that the influence of the ambient light is not reflected in the calibration of the gradation reproduction characteristics related to the reference color monitor. It is.

That is, also in this embodiment , (i) the white color calibration of the reference color monitor can reflect the influence of ambient light, and (ii) calibration using a non-contact colorimeter. Since only one reference color monitor is used, the time and effort required for measurement can be minimized. (Iii) Only one reference color monitor is calibrated visually. (Iv) Calibration of a color monitor other than the reference color monitor is performed using a contact-type colorimeter, so that there is no variation and it can be performed stably. It is done.

  The calibration method for a plurality of color monitors and the effect thereof according to the present invention have been described above. Next, a specific method for color monitor calibration and a specific example for profile creation will be described. . Various methods are known for white color calibration, tone reproduction characteristics calibration, and profile creation, and each method described below is merely an example. Let me add.

(1) Configuration Example of Computer System 100, 200 First, a more detailed configuration example of the computer system 100, 200 shown in FIG. 1, particularly, a configuration example of the main control means 101, 201 is shown in FIG. Note that the configuration shown in FIG. 3 shows only the part related to the calibration process and the profile creation process, and the others are omitted. 3 shows the configuration of the computer system 100, the configurations of the computer systems 100 and 200 are all the same. Therefore, the configuration shown in FIG. 3 is also the configuration of the computer system 200.

  In FIG. 3, the main control unit 101 includes a first color conversion unit 14, a second color conversion unit 15, a portion surrounded by a broken line indicated by reference numeral 20, and a control unit 18. A portion surrounded by a broken line 20 is generally called a video board. There are various configurations of the video board 20, but here, look-up tables (LUT) 16R, 16G, and 16B for determining input / output characteristics for digital color signals of R, G, and B, and digital It is assumed that each of the color signals R, G, and B is composed of D / A converters 17R, 17G, and 17B that convert analog signals into analog color signals.

  The first color conversion unit 14 converts RGB or CMYK of image data input from the outside into a color in a standard color space, and here, converts it into XYZ. The first color conversion unit 14 is created in advance and registered in the first color conversion unit 14. Note that the profile to be registered in the first color conversion unit 14 may be created by a known method. The profile registered in the first color conversion means 14 and the creation method thereof are not essential matters in the present invention.

  The second color conversion means 15 converts XYZ, which is a color value in the standard color space, into colors in the RGB color space unique to the color monitor 104 to be calibrated and profile-created. The profile created by the profile creation process is registered.

  The first color conversion unit 14 and the second color conversion unit 15 are actually software, and are performed by software using a profile in the previous stage of the video board 20, as shown in FIG.

  The LUTs 16R, 16G, and 16B define input values versus output values of R, G, and B digital color signals, respectively, and input / output characteristics determined by a gradation reproduction characteristic calibration process described later are registered. Is done. The D / A converters 17R, 17G, and 17B convert R, G, and B digital color signals into analog color signals, respectively, and these analog color signals are input to the analog input terminal of the color monitor 104. The Here, it is assumed that the D / A converters 17R, 17G, and 17B all include amplifiers, and the gains of these amplifiers can be controlled by the control means 18.

  Here, the video board 20 is included in the main control unit 101 of the computer system 100. However, a color monitor used for color management may have a function equivalent to that of the video board 20. Therefore, if it is possible to control the parts corresponding to the video board 20 of such a color monitor from the control means 18, those parts of the color monitor are controlled by the control means 18. However, in this case, as shown in FIG. 3, the main control means 11 performs the conversion until the analog color signal is converted, and the color monitor 104 is connected to the D / A converter 17R, In the following description, it is assumed that RGB analog color signals, which are the outputs of 17G and 17B, are input and displayed, and the calibration is performed by controlling the video board 20 as described later.

  Here, the D / A converters 17R, 17G, and 17B include amplifiers and control the gains of those amplifiers. However, the D / A converters 17R, 17G, and 17B include amplifiers. If not, a digital color signal amplifier may be provided in front of each of the D / A converters 17R, 17G, and 17B to control the gain of these amplifiers, or the D / A converter Analog color signal amplifiers may be provided in the subsequent stages of 17R, 17G, and 17B, and the gains of these amplifiers may be controlled. In particular, recent liquid crystal color monitors include a type in which digital color signals are directly input and displayed. When such a color monitor is used, each of the D / A converters 17R, 17G, and 17B is used. Naturally, it is necessary to provide amplifiers for digital color signals in the preceding stage and control the gains of those amplifiers, and the digital color signals output from the amplifiers may be directly input to the color monitor. .

  As described above, the control unit 18 includes a program for performing calibration processing of white tone and tone reproduction characteristics for the reference color monitor and color monitors other than the reference color monitor, and profile creation A program for performing the above process is incorporated. For this purpose, the control unit 18 writes a profile to the second color conversion unit 15, writes input / output characteristics to the LUTs 16R, 16G, and 16B, and controls the gains of the D / A converters 17R, 17G, and 17B. Furthermore, an output terminal for RGB digital color signals is provided. In FIG. 3, RGB output from the control means 18 is input before the LUTs 16R, 16G, and 16B.

  The above is the outline of the configuration example of the main control unit 101. Next, an example of a calibration and profile creation method will be described. In the following, for convenience, each digital color signal of R, G, and B is expressed by 8-bit data and takes 256 gradation values from 0 to 255.

  In addition, various windows and messages are displayed on the reference color monitor 104, and a gray scale, which will be described later, is displayed on the reference color monitor 104 by the control means 18 from the RGB output terminal of the control means 18 for digital color signals constituting an image to be displayed. This is performed by outputting, and this is the same for color monitors other than the reference color monitor 104.

(2) Calibration for Reference Color Monitor The calibration for the reference color monitor 104 is performed in step S2 of FIG. As described above, there are two types of calibration: white color calibration and gradation reproduction characteristic calibration.

(2-1) White Color Calibration First, white color calibration processing for the reference color monitor 104 will be described. As described above, in the calibration of the white color of the reference color monitor, there are two cases, that is, the case of visual observation and the case of using a non-contact type colorimeter as a measuring means.

(2-1-1) When visually calibrating When white color calibration is performed, the operator prepares a reference white object to be used as a reference white beforehand, and the input means 102 visually checks the reference color monitor. The menu for white color calibration (not shown) is selected and instructed to execute. As a result, the control means 18 clears the input / output characteristics of the LUTs 16R, 16G, and 16B, writes the characteristics of output value = input value, and sets the gains of the amplifiers of the D / A converters 17R, 17G, and 17B to a predetermined value. Further, for example, a digital color signal having a gradation value of 255 for each of R, G, and B is output from the RGB output terminal. Accordingly, since no image data is input from the outside at this time, an analog color signal having the maximum amplitude is input to the reference color monitor 104 for both RGB.

  In the calibration of the white color visually, the operator adjusts the white of the reference color monitor 104 while visually comparing the white of the reference white object with the white displayed on the reference color monitor 104. The adjustment can be performed by various methods. For example, when the reference color monitor 104 is provided with a brightness adjustment knob or a color balance adjustment knob, the adjustment can be performed by operating these adjustment knobs. Further, for example, it can be performed by displaying a window for white color adjustment as shown in FIG. 4 on a part of the screen of the reference color monitor 104 on which white is displayed. This example will be described with reference to FIG.

  In the window shown in FIG. 4, for each of RGB, a bar indicating the amplitude of the color signal as a percentage is displayed, and scroll bars 21, 22, and 23 are displayed in each bar. Then, the operator operates the scroll bars 21, 22, and 23 by the input unit 102 while comparing the white displayed on the reference color monitor 104 with the reference white object, and adjusts the white colors of the two to match. To do. At this time, when the scroll bar 21, 22 or 23 is operated, the control means 18 takes in the change amount of which color and how much, and D / A conversion of the corresponding color according to the change amount. Control the gain of the amplifier of the instrument.

  As a result, the white color displayed on the screen changes, so that the operator operates the scroll bar 21, 22 or 23 by trial and error, and the displayed white color and the white color of the reference white object. When the taste matches, the “OK” button in the window of FIG. 4 is operated. When the “OK” button is operated, the control means 18 maintains the gains of the amplifiers of the respective D / A converters 17R, 17G, and 17B in the state at that time. As a result, the white color is visually calibrated.

  In place of the window as shown in FIG. 4, a window for directly inputting the gradation values for each of RGB or a window for inputting the respective gains of the D / A converters 17R, 17G, and 17B is displayed. It will be apparent that the white color can also be calibrated.

  Through the above processing, it is possible to calibrate the white color of the reference color monitor 104 reflecting the influence of ambient light.

(2-1-2) In the case of using a non-contact type colorimeter In this case, the operator also prepares a reference white object, and further connects the non-contact type colorimeter as the colorimeter 103 to the I / F 19. The input means 102 selects a calibration menu (not shown) for white color using a non-contact colorimeter for the reference color monitor, and instructs execution. As a result, the control means 18 starts the white color calibration process using the non-contact type colorimeter. First, similarly to the visual white color calibration process, the control means 18 18 clears the input / output characteristics of the LUTs 16R, 16G, and 16B, writes the characteristic that the output value = the input value, and sets the gain of the amplifier of the D / A converters 17R, 17G, and 17B to a predetermined value, for example, the maximum Further, a digital color signal having R, G and B gradation values of 255 is output from the RGB output terminal.

  First, the operator points the non-contact colorimeter toward the reference white object and instructs the execution of measurement from the input means 102. As a result, the control means 18 gives a color measurement instruction to the color measuring device 103 which is a non-contact type color measuring device. As a result, the non-contact colorimeter starts color measurement and notifies the control means 18 of the color measurement value. Thereby, the control means 18 takes in the white colorimetric value of the reference white object.

  Next, the operator points the colorimeter 103 made of a non-contact type colorimeter toward the screen of the reference color monitor 104 and instructs the execution of white measurement displayed on the screen. As a result, the control means 18 gives a color measurement instruction to the colorimeter 103. As a result, the colorimeter starts color measurement and notifies the control means 18 of the color measurement value.

  Upon receiving the white colorimetric value of the screen in this way, the control means 18 compares the white colorimetric value of the screen with the white colorimetric value of the reference white object previously captured, If the difference is within a predetermined error range, the currently displayed white is assumed to be the same as the white of the reference white object, and the gains of the amplifiers of the D / A converters 17R, 17G, and 17B are maintained as they are. This completes the white color calibration process.

  However, if the difference between the white colorimetric value of the screen and the white colorimetric value of the reference white object is outside the range of the predetermined error, the control means 18 is connected to the amplifier of the D / A converter 17R. A new white is displayed by changing the gain, the gain of the amplifier of the D / A converter 17G, and / or the gain of the amplifier of the D / A converter 17B. At this time, the gradation values of R, G and B output from the control means 18 are not changed and all remain 255, but the gain of the amplifier of the D / A converter 17R, the amplifier of the D / A converter 17G And / or the gain of the amplifier of the D / A converter 17B is changed, so that new white is displayed.

  Then, the control means 18 gives the colorimetry instruction to the colorimeter 103 again, takes in a new white colorimetric value from the colorimeter 103, and measures the white colorimetric value of the screen and the white color of the reference white object. The color value is compared to determine whether the difference between the two is within a predetermined error range or out of the predetermined error range. If the difference is out of the error range, the control means 18 further includes D / A converters 17R, 17G, The operation of displaying any new white by controlling one or more of 17B and measuring the color is repeated.

  That is, in this process, the control means 18 controls one or more of the D / A converters 17R, 17G, and 17B to display white, and the colorimetric value and the white colorimetric measurement of the reference white object. The operation of comparing the values is repeated by trial and error until the difference between the two colorimetric values falls within the error range. As processing at this time, for example, when the colorimetric values of the two are compared and the displayed white is more red than the white of the reference white object, the gain of the amplifier of the R D / A converter 17R On the contrary, if the displayed red color is small, the gain of the amplifier of the D / A converter 17R may be increased.

  When the white colorimetric value of the screen falls within the range of error from the white colorimetric value of the reference white object, the control means 18 determines that the white color of both coincides, and performs D / A conversion. The gains of the amplifiers 17R, 17G, and 17B are kept as they are.

  Through the above processing, the white color calibration reflecting the influence of the ambient light is performed on the reference color monitor 104.

(2-2) Calibration of Tone Reproduction Characteristics When the white color calibration for the reference color monitor 104 is completed as described above, the control means 18 performs the following processing in step S2 of FIG. Then, the gradation reproduction characteristic calibration process is started. As described above, in the reference example of the present invention, the measurement is performed using a visual or non-contact colorimeter, and in the embodiment of the present invention , the measurement is performed using a contact colorimeter. Set whether to use the means.

  Hereinafter, processing in each case will be described. It should be noted that since the calibration of the white color has already been completed when the calibration of the gradation reproduction characteristics is started, the gain of the amplifier of each D / A converter 17R, 17G, 17B is the white color. The values set in the taste calibration are held, and the LUTs 16R, 16G, and 16B are still cleared, that is, have characteristics in which output value = input value.

(2-2-1) Visual observation When visual observation is set as the measurement means, the control means 18 executes a visual gradation reproduction characteristic calibration process for the reference color monitor. Various processes for calibration of the gradation reproduction characteristics by visual observation are known, and the methods disclosed in the above-mentioned Patent Documents 1, 2, 3, or 4 can be used. An example of a characteristic calibration process will be briefly described.

  The control means 18 first displays a window (not shown) requesting input of a desired γ value. When the desired γ value is numerically input and execution is instructed in the window, the input is performed. Store the γ value.

  Next, as shown in FIG. 5A, the control means 18 controls the reference color monitor 104 so that the background color is black (part a in the figure) and the central part is variable red (part b in the figure) ( A measurement screen with a value R is displayed together with the scroll bar 24. When the scroll bar 24 is operated on this screen, the control means 18 detects the amount of change in R by the scroll bar 24 and changes the value of R output from the control means 18 to the LUT 16R according to the amount of change. Accordingly, the portion indicated by b in FIG. 5 can be changed from black (R = G = B = 0) to red (R = 255, G = B = 0).

  Then, the operator ends the operation of the scroll bar 24 and operates the “Next” button at the position where the portion b in FIG. 5A starts to change from black to red. Thereby, the control means 18 at this time stores the value of R output at that time as an offset amount αr between black and red. Similarly, the control means 18 obtains an offset amount αg between black and green and an offset amount αb between black and blue.

  Based on the obtained offset amounts αr, αg, αb, the control means 18 creates a table of input gamma characteristics of previously inputted γ values for each of R, G, B, and the created input gammas. The characteristic tables are written in the LUTs 16R, 16G, and 16B, respectively. Note that when the input gamma characteristic table is created, the input gamma characteristic table always passes through the point (input value = 255, output value = 255). This completes the gradation reproduction characteristic calibration.

  FIG. 5B shows an example of the gamma curve created. A curve indicated by a thick solid line in FIG. 5B shows an example of an input gamma characteristic table created for R and written in the LUT 16R. The thick broken line in the figure passes through the point where output = input = 0. , Shows a curve having an input γ value.

  As described above, according to this processing, the offset amount αr between black and red, the offset amount αg between black and green, and the offset amount αb between black and blue are all determined by the operator's visual observation. , 16B, the input gamma characteristic table reflects the influence of ambient light.

(2-2-2) When using a non-contact colorimeter When a non-contact color meter is set as the measurement means, the control means 18 uses the non-contact color meter for the reference color monitor. Executes the calibration process of tone reproduction characteristics. Hereinafter, an example of calibration processing of gradation reproduction characteristics using a non-contact type colorimeter will be schematically described. In this case, the operator connects a non-contact color measuring device as the color measuring device 103 to the I / F 19 in advance and directs it to the screen of the reference color monitor 104.

  The control means 18 first displays a window (not shown) requesting input of a desired γ value. When the desired γ value is numerically input and execution is instructed in the window, the input is performed. Store the γ value.

  Next, the control unit 18 outputs RGB having a predetermined value to the LUTs 16R, 16G, and 16B. At this time, the values of R, G, B are all the same (R = G = B). Therefore, a gray scale corresponding to the signal value is displayed on the screen of the reference color monitor 104.

  When the gray scale is displayed, the control unit 18 gives a color measurement instruction to the colorimeter 103 and takes in the colorimetric value from the colorimeter 103. In this case, since a non-contact colorimeter is used as the colorimeter 103, it is natural that the influence of ambient light is reflected on the colorimetric value.

  The control means 18 changes the RGB values in various ways (however, the RGB gradation values are the same value), and repeats gray scale display and colorimetry. The number of gray scales to be displayed can be arbitrarily determined. As the number of gray scales increases, the gradation reproduction characteristics can be determined with higher accuracy.

  When the predetermined number of gray scales are displayed and the color measurement is completed, the control means 18 determines the gradation value of the input signal in the reference color monitor 104 and the actual value based on the color measurement value and the gray scale signal value. A gradation reproduction characteristic indicating a relationship with display luminance, specifically, a relationship between input signal gradation value and display luminance is obtained. Next, the control means 18 compares the gradation reproduction characteristic with a gradation reproduction characteristic for realizing a gamma characteristic of a γ value input in advance, and R, G of a certain gradation value from the control means 18. , B should be changed by the LUTs 16R, 16G, and 16B so that the luminance actually displayed on the reference color monitor 104 is on the gamma characteristic of the input γ value. Create a table to determine what.

  An outline of this process will be described. Now, for example, the gamma curve having the previously set γ value is shown by the broken line in FIG. 6, and the input signal to the reference color monitor 104 obtained by actually measuring a predetermined number of gray scales. Assume that the smoothed curve obtained by plotting the relationship between the gradation characteristics and the colorimetric luminance is as shown by the solid line in FIG. At this time, paying attention to a certain input signal gradation value K1, the actual colorimetric luminance is different from the luminance Q to be displayed because it is not on the dashed gamma curve. In this case, the control means 18 has an input signal level that becomes the luminance Q to be displayed when the input signal tone value K1 is input on the solid line input signal tone value vs. colorimetric luminance curve. Find the key value. In this case, K2. Therefore, the control means 18 is set to output a signal having a gradation value of K2 when the gradation value of the input signal is K1 in each table of the LUTs 16R, 16G, and 16B. As a result, when the R, G, and B tone values of a pixel having image data are all K1, the tone values of the signals output from the LUTs 16R, 16G, and 16B are all K2, and the reference color monitor The gray brightness displayed on the screen 104 is Q.

  The above processing is performed for all input signal gradation values. As a result, a table in which the gradation value of the output signal is associated with the gradation value of the input signal for all gradation values is obtained, and the control means 18 writes this table in the LUTs 16R, 16G, and 16B. Therefore, in this process, all three LUTs LUT16R, 16G, and 16B are the same. This completes the gradation reproduction characteristic calibration process using the non-contact colorimeter.

  In the above description, the γ value is set as the tone reproduction characteristic, but the curve of the input signal tone value to the reference color monitor 104 vs. luminance is directly set as desired. Also good. In the above description, the gray scale is displayed. However, a person skilled in the art may display and measure a so-called step chart in which gradation values are changed for each primary color of RGB. it is obvious. As described above, when the γ value is set and the gray scale is displayed and measured, the input / output characteristics registered in the LUTs 16R, 16G, and 16B are the same, but for each primary color. It is also possible to set the input signal gradation value vs. luminance curve to the reference color monitor 104, display and measure a step chart for each primary color, and perform the same processing as described above. In this case, the input / output characteristics written in the LUTs 16R, 16G, and 16B are generally different from each other.

(2-2-3) When using a contact-type colorimeter This is a process in the embodiment of the calibration method for a plurality of color monitors according to the present invention described above, and the contact-type colorimeter is set as a measuring means. In this case, the control means 18 executes the calibration process of the gradation reproduction characteristic by the contact type colorimeter for the reference color monitor. The process at this time is different only in the colorimeter to be used. Since the process itself is the same as the process using the non-contact colorimeter described above, the description thereof is omitted. In this case, the operator connects a contact-type colorimeter as the colorimeter 103 to the I / F 19 in advance and contacts the screen of the reference color monitor 104 in advance.

(3) Profile Creation for the Reference Color Monitor This profile creation for the reference color monitor 104 is performed following the calibration process for the reference color monitor 104 in step S2 of FIG. In this profile creation process, as is well known, the color in RGB color space unique to the color monitor targeted for profile creation is changed to a color in a standard color space such as CIE XYZ, CIE L ^* a ^* b ^*. Two color conversion means are created: a first color conversion means for conversion and a second color conversion means for converting the color in the standard color space to a color in RGB color space unique to the color monitor. .

  First, a profile for a color monitor will be briefly described. When CIE XYZ is used as a standard color space, signals with gradation values R, G, and B are input to the reference color monitor 104, and colorimetric values of colors actually displayed on the reference color monitor 104 at that time are input. When X, Y, and Z are used, it is known that X, Y, and Z are simply expressed as determinants represented by the following equation (1).

Here, γ is a gamma value, XR, YR, and ZR are colorimetric chromaticities when only a red primary color (R = 255, G = B = 0) is displayed, and XG, YG, and ZG are green primary colors (R = 0, G = 255, B = 0) only when the colorimetric chromaticity is displayed, XB, YB, ZB are the measurements when only the blue primary color (R = 255, G = B = 0) is displayed. Color chromaticity.

  That is, the expression (1) represents the colorimetric values X, Y, and Z of the color displayed when the signals having the gradation values of R, G, and B are input to the reference color monitor 104, respectively. This is in addition to the first color conversion means for converting the color of the color space of RGB unique to the reference color monitor 104 out of the profile of the reference color monitor 104 into the color of the standard color space of CIE XYZ. Don't be. Then, the color in the standard color space of CIE XYZ is expressed by RGB specific to the reference color monitor 104, where the equation obtained by solving equation (1) for R, G, B is another color conversion means of the profile. This is the second color conversion means for converting the color into the color space.

  Therefore, when creating the profile, the control means 18 obtains the expression (1) to create the first color conversion means, and further solves it for R, G, B to create the second color conversion means. Then, a process of writing them into the second color conversion means 15 shown in FIG. 3 is performed.

  In order to obtain equation (1), it is necessary to first measure the chromaticity of the three primary colors RGB. This is because it is necessary to obtain XR, YR, ZR, XG, YG, ZG, XB, YB, ZB in the formula (1). Also, for creating a profile, the tone reproduction characteristics of the target reference color monitor 104 must be in a desired state. Furthermore, although it is not reflected in the equation (1), it is necessary to measure the white color because the white value must be described in the ICC standard. Thus, when creating a profile, it is necessary to measure three items: measurement of white color, measurement of tone reproduction characteristics, and chromaticity of the three primary colors of RGB.

  However, when the profile creation process is started, the calibration process has already been completed, and the white color and gradation reproduction characteristics of the reference color monitor 104 have already been adjusted to a desired state. Accordingly, as the white value necessary for profile creation, the white value measured in the white color calibration process may be used as it is, and the γ value in the equation (1) represents the tone reproduction characteristic. The γ value set in the calibration process may be used as it is. Therefore, in this case, RGB primary color chromaticities are measured, and red primary color chromaticities XR, YR, ZR, green primary color chromaticities XG, YG, ZG, and blue primary color chromaticities XB, YB, ZB are obtained. Just measure. Hereinafter, measurement of RGB primary color chromaticity will be described.

(3-1) Measurement of RGB primary color chromaticity Here, since RGB primary color chromaticity is assumed to be performed using a contact-type colorimeter, measurement using a contact-type colorimeter will be described. However, it can also be performed using a non-contact colorimeter, and the process using a contact-type colorimeter is different from that using a non-contact-type colorimeter, except that the colorimeter used is different. It is the same.

  At this time, the operator connects a contact type colorimeter as the colorimeter 103 to the I / F 19 in advance, and makes it contact the screen of the reference color monitor 104. In this process, the control means 18 first outputs the primary color of red (R = 255, G = B = 0), gives a colorimetric instruction to the colorimeter 103, takes in the colorimetric value, Let the colorimetric values be XR, YR, ZR in the matrix on the right side of equation (1). Next, the control unit 18 outputs green primary colors (R = 0, G = 255, B = 0), gives a colorimetric instruction to the colorimeter 103, takes in the colorimetric values, and performs this colorimetry. The values are XG, YG, and ZG in the matrix on the right side of equation (1), and the blue primary colors (R = G = 0, B = 255) are output, and the colorimeter 103 is instructed to perform colorimetry. Then, the colorimetric values are taken in, and these colorimetric values are set as XB, YB, ZB in the matrix on the right side of equation (1).

(3-2) Profile Creation In this way, when the white value, the gradation reproduction characteristic, that is, the γ value, and the RGB three primary color chromaticities are obtained, the control means 18 converts the expression (1) into the first color conversion. Further, the second color conversion means is obtained by solving the equation (1) for RGB, and these two color conversion means are written in the second color conversion means 15. This completes the profile creation process. Note that the second color conversion means 15 in FIG. 3 performs color conversion from XYZ to RGB, so that only the second color conversion means is used in the actual color conversion.
(4) Measurement and storage of white value and gradation reproduction characteristics This is the process performed in step S3 of FIG. 2, and the computer system 100 corresponding to the reference color monitor 104 performs the calibration performed on the reference color monitor 104. Measure the white and tone reproduction characteristics determined by the application and save them. At this time, a contact colorimeter is used as a measuring means. This is because measurement can be performed easily and stably.

  At this time, the operator connects a contact-type colorimeter as the colorimeter 103 to the I / F 19 in advance and brings the colorimeter 203 into contact with the screen of another color monitor 204. At this time, the input / output characteristics determined in the calibration of the gradation reproduction characteristics are written in the LUTs 16R, 16G, and 16B, and the gains of the D / A 17R, 17G, and 17B amplifiers are white. The value is determined in the color calibration.

  Then, the control means 18 outputs a digital color signal whose R, G, B gradation values are all 255 from the RGB output terminal. As described above, the gains of the D / A 17R, 17G, and 17B amplifiers are the values determined in the white color calibration, so that the reference color monitor 104 has a white color calibration. The white color set in the menu is displayed. Then, the control unit 18 gives a measurement instruction to the colorimeter 103, takes in the colorimetric value, and stores the colorimetric value as a white measured value. Then, the control means 18 writes the white measurement value into the profile.

  Next, the control means 18 sequentially displays the same image pattern as that displayed when the gradation reproduction characteristic is calibrated, gives a measurement instruction to the colorimeter 103 each time, takes in the colorimetric value, This colorimetric value is stored as a measurement value of the gradation reproduction characteristic. As in the case described above, when a predetermined number of gray scales are displayed at the time of gradation reproduction characteristic calibration, the gray scales are sequentially displayed, and a measurement instruction is given to the colorimeter 103 each time. Then, the colorimetric value is taken in, and this colorimetric value is stored as a measurement value of the gradation reproduction characteristic. In addition, when a step chart for each primary color is displayed at the time of gradation reproduction characteristic calibration, these step charts are sequentially displayed, and a measurement instruction is given to the colorimeter 103 each time, and a colorimetric value is obtained. It is only necessary to capture and store this colorimetric value as a measurement value of the gradation reproduction characteristic. If a γ value is set during calibration of the gradation reproduction characteristics, it is preferable to store the γ value.

(5) Calibration for a color monitor other than the reference color monitor A color monitor other than the reference color monitor 104, in the case of FIG. 1, a color monitor 204 (hereinafter simply referred to as another color monitor 204). This calibration is performed in step S4 of FIG. As described above, the calibration of the white color tone and gradation reproduction characteristics of the other color monitor 204 is performed using the contact-type colorimeter. In the following, the outline of the processing will be described. For convenience, the reference numerals of the components of the computer system 200 shown in FIG. Shown as a three-digit code. Therefore, the control means 18 of FIG. 3 is labeled “218” in the computer system 200. The same applies to other cases.

(5-1) White Color Calibration When calibrating the white color of another color monitor 204, it was measured and stored in step S3 of FIG. 2 as the target value of the white color. The white measurement value obtained as a result of the calibration performed on the reference color monitor 104 is used. For example, the stored white value may be stored in an appropriate storage medium such as a flexible disk from the control unit 18 of the computer system 100 and read into the control unit 218 from the storage medium.

  Then, the operator connects a contact-type colorimeter as the colorimeter 203 to the I / F 219 in advance, contacts the colorimeter 203 with the screen of the other color monitor 204, and uses the input means 203 to Instructs execution of the white color calibration processing of the color monitor. As a result, the control means 218 starts the process of white color calibration using the contact-type colorimeter for the other color monitors. First, the control means 218 enters the LUTs 16R, 16G, and 16B. The output characteristic is cleared, the characteristic of output value = input value is written, the gain of the amplifiers of the D / A converters 17R, 17G, and 17B is set to a predetermined value, for example, the maximum gain value, and further from the RGB output terminal , R, G, and B all output digital color signals of 255.

  The subsequent processing differs only in that the target value of white is not a reference white object but is taken from the computer system 100 corresponding to the reference color monitor 104 and that a contact-type color measuring device is used as the color measuring device 203. This is the same as the white color calibration processing for the reference color monitor 104 described above. That is, the control unit 218 displays white by controlling any one or more of the D / A converters 217R, 217G, and 217B, and compares the colorimetric value with the target white value. When the difference between the two is within the error range, the gains of the amplifiers of the D / A converters 217R, 217G, and 217B are used as they are. The process of maintaining the state is executed.

  With the above processing, it is possible to calibrate the white color of the other color monitor 204. As is apparent from the above, the white value used in this calibration is influenced by the ambient light. As a result, the influence of ambient light is reflected in the calibration of the white color of the other color monitor 204 as a result. At this time, since the contact-type colorimeter is used, the measurement can be performed stably.

(5-2) Calibration of gradation reproduction characteristics When the gradation reproduction characteristics of other color monitors 204 are calibrated, they are measured and stored in step S3 of FIG. 2 as target values of gradation reproduction characteristics. The measurement value of the gradation reproduction characteristic is used. For example, the stored measurement value of the gradation reproduction characteristic may be stored in a suitable storage medium such as a flexible disk from the control unit 18 of the computer system 100 and read into the control unit 218 from the storage medium.

  That is, the target of the gradation reproduction characteristics in this case is the display brightness of the reference color monitor 104 with respect to the RGB gradation values output from the control means 18 in the reference color monitor 104 after calibration. It becomes the relationship.

  In the subsequent processing, the target value of the gradation reproduction characteristic is not input and set by the operator, but is read from the computer system 100 corresponding to the reference color monitor 104 and a contact colorimeter is used as the colorimeter 203. It is the same as the above-described calibration process of gradation reproduction characteristics using a non-contact colorimeter for the reference color monitor 104 except that it is used.

  That is, the control unit 218 performs a predetermined number of gray scale display and color measurement, and based on the color measurement value and the gray scale signal value, the gradation value of the input signal in the other color monitor 204, Gradation reproduction characteristics showing the relationship with the actual display luminance, specifically, the relationship between the input signal gradation value and the display luminance is obtained, and then, the gradation reproduction characteristic and the target level acquired previously are obtained. From the comparison with the tone reproduction characteristics, when the control means 218 outputs R, G, B of a certain gradation value, the luminance actually displayed on the other color monitor 204 becomes the target gradation reproduction characteristic. In order to do so, a table that defines how to be changed by the LUTs 216R, 216G, and 216B is created, and processing for registering the created table in the LUTs 216R, 216G, and 216B is executed. It is.

Through the above process, the gradation reproduction characteristics of other color monitors 204 are calibrated. As is clear from the above description, as in the reference example of the present invention, when the gradation reproduction characteristics of the reference color monitor 104 are calibrated visually or using a non-contact colorimeter, Since the target gradation reproduction characteristics captured from the control means 18 of the computer system 100 reflect the influence of the environmental light, as a result, the environmental light is also used in the calibration of the gradation reproduction characteristics of the other color monitors 204. Will be reflected.

On the other hand, when the calibration of the tone reproduction characteristics of the reference color monitor 104 is performed using a contact colorimeter as in the embodiment of the present invention , the calibration is performed from the control means 18 of the computer system 100. As described above, the target tone reproduction characteristics do not reflect the influence of ambient light, but are effective when a monitor hood is attached to the color monitor.

(6) Profile Creation for Other Color Monitors Profile creation for other color monitors 204 is performed following the calibration process for other color monitors 204 in step S4 of FIG. This process is the same as the profile creation process for the reference color monitor 104 described above.

  That is, at the time of starting the profile creation process, the white value is already obtained, and the tone reproduction characteristics, specifically the γ value, are also known. The measurement of the RGB primary color chromaticity described in the section is performed using a contact-type colorimeter, and then the profile creation process described in the section (3-2) is performed. As a result, the created profile for the other color monitor 204 is written in the second color conversion means 215.

  As described above, according to the present invention, in a technical field where it is desired to use a plurality of color monitors and to calibrate all the color monitors to the same state, the influence of ambient light is reflected. In addition, a calibration method capable of minimizing the labor required for measurement is provided.

It is a figure which shows the state by which the several color monitor is arrange | positioned. 5 is a flowchart for explaining an embodiment of the present invention while showing a reference example of a calibration method for a plurality of color monitors according to the present invention . 2 is a diagram illustrating a more detailed configuration example of a computer system 100, particularly, a configuration example of a main control unit 101. FIG. FIG. 10 is a diagram for explaining a process of calibrating white tint visually with respect to a reference color monitor. FIG. 10 is a diagram for describing a calibration process of visual gradation reproduction characteristics for a reference color monitor 104; FIG. 10 is a diagram for explaining a gradation reproduction characteristic calibration process using a non-contact colorimeter for the reference color monitor 104;

Explanation of symbols

14 ... 1st color conversion means 15 ... 2nd color conversion means 16R, 16G, 16B ... LUT
17R, 17G, 17B ... D / A converter 18 ... control means 19 ... I / F
20 ... Video board 100, 200 ... Computer system 101, 201 ... Main control means 102, 202 ... Input means 103, 203 ... Colorimeter 104, 204 ... Color monitor

Claims (1)

  Select a reference color monitor as a reference from a plurality of color monitors, and calibrate the white color of the selected reference color monitor using a visual or non-contact colorimeter as a measuring means, Calibration of gradation reproduction characteristics is performed using a contact colorimeter as a measuring means, and the white and gradation reproduction characteristics after calibration are measured using a contact colorimeter, and a color other than the reference color monitor is measured. Calibration of a plurality of color monitors characterized in that the calibration of the monitor is performed using a contact colorimeter as a measuring means with the white value and gradation reproduction characteristics measured for the reference color monitor as target values. Method.

Images