JPH07105375A - Color adjustment device - Google Patents

Abstract

PURPOSE:To adjust a color of a printed matter printed out on a color monitor in color under a condition of observation independently of a change in a lighting condition and a spectral reflectance characteristic of paper. CONSTITUTION:The device is made up of a lighting light spectrum storage means 104 storing a spectrum of a lighting light used when a printed matter is observed, a spectrum colorimetry means 103 to measure a paper spectral reflectance characteristic, a color correction means 107 applying color correction to a picture on a monitor 109 based on a spectrum of the lighting light stored in the lighting light spectrum storage means and a spectral reflectance characteristic of paper measured by the spectral colorimetry means, a chromatic adaptation color stimulus arithmetic means 108 obtaining a chromatic adaptation color stimulus based on the spectrum of the lighting light stored in the lighting light spectrum storage means and an adaptation visual field presentation means generating a light to provide the chromatic adaptation color stimulus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, when a hard copy of a color image is obtained by a printing device based on color image data, can confirm the finished state on a monitor and can adjust the hue. Regarding the adjusting device.

[0002]

2. Description of the Related Art When color printing is performed by a color printer or the like, a color signal is given and printing is performed, but in the color printer or the like, at least three colors of cyan (C), magenta (M) and yellow (Y) are used as ink. To do. Then, various colors are reproduced by using the three primary colors.

That is, in the case of color printing by a printer, each pixel is represented by a plurality of points in order to make each pixel appear to have one color when viewed in pixel units. In order to make it visible, it depends on the ratio of the area ratio of the three primary colors in the pixel.

Therefore, the color image signal to be given to the printer is such that a desired color is given at the level of each signal of the three primary colors in pixel units, which is expressed on the printer in the form of an area ratio.

In the field of printing, there is an increasing demand for a technique for reproducing the completion of a hard copy (printed matter) on a soft copy (color monitor display screen) from the viewpoint of eliminating waste from test printing.
That is, in order to save resources, reduce costs, and save time, hard copy (printed matter) output from the printer.
The finished product is displayed as an image on a color monitor device by a color image signal given to the printer, reproduced on the color monitor display screen, and while looking at the color monitor screen to obtain a desired color tone before printing. There is a demand for correcting the data of the color image signal so that the hard copy need not be used in the color adjustment stage of the printed matter.

[0006] By the way, for human vision, the appearance of colors of a color printed matter is influenced by the ink of each color used, the paper, the observation environment (illumination), and the like. Therefore, the spectral spectrum of the external light of the observation environment is stored so that the color of the printed matter can be predicted even when the illumination of the environment for performing the color adjustment work and the illumination of the environment for observing the printed matter are different. ,
There has been proposed an apparatus which corrects a color change of a printed matter due to external light and displays it on a color monitor (Japanese Patent Application Laid-Open No. Hei.
255025). Of course, in this case, the difference in color development between the hard copy and the soft copy is corrected in advance so that the two have the same shade and are visible to the human eye.

However, even if a color adjustment is made according to the difference in external light while observing a color monitor using this device and the display is a target color, a correction is made based on the difference in illumination. Since the illumination of the environment for color adjustment affects the adaptation state of the person who performs the color adjustment work, the appearance of the color on the color monitor is different from that of the printed matter.

[0008]

Even if a color stimulus having the same spectral characteristic is used, the appearance of the color differs depending on what kind of color stimulus the observer observes. Therefore, if the illumination of the environment for color adjustment is significantly different from the illumination of the environment for observing the printed matter, even if the device for color adjustment is used to perform correction based on the difference in illumination, Since the lighting affects the adaptation state of the eyes of the person performing the color adjustment work, the appearance of the colors on the color monitor is different from that of the printed matter.

On the other hand, when the spectral reflectance characteristic of the paper changes, such as when printing on colored paper, the appearance of the color of the printed matter changes. Further, even if it is generally called white paper, its chromaticity varies depending on the paper, and this also changes the appearance of the color of the printed matter. The change in the appearance of the color caused by the change in the spectral reflectance characteristics of the paper cannot be reproduced only from the spectral spectrum of the illumination.

Therefore, the present invention has been made in view of the above problems, and is intended to observe the color of the printed matter regardless of the change of the illumination condition or the change of the spectral reflectance characteristic of the paper. An object of the present invention is to provide a color adjusting device capable of faithfully reproducing a color tone on a color monitor and performing printing capable of reproducing a desired color tone without performing a trial printing.

[0011]

In order to achieve the above object, the present invention is configured as follows. That is, it has a color monitor for displaying a color image according to color image data and a color adjusting operation means for giving a color adjusting operation amount, and corrects color image data used for printing in accordance with the operation amount of the color adjusting operating means. Output color adjusting means, a colorimeter for measuring the spectral reflectance characteristics of the paper used for printing, an illumination light spectrum storage means for storing the spectral spectrum of the illumination light used when observing the printed matter, and this illumination light A correction device that performs data correction to perform color correction of an image on the color monitor using the spectral data of the illumination light from the spectrum storage means and the measurement value from the colorimeter,
Color order application color stimulus value calculating means for obtaining a color order application color stimulus value using the spectral data of the illumination light from the illumination light spectrum storage device, and color order application obtained by this color order application color stimulus value calculating means It comprises an adaptive visual field presenting means for generating light of color stimulus.

[0012]

In the present apparatus having such a configuration, the color adjusting operation means of the color adjusting apparatus is operated so that the desired color shade is obtained on the color monitor, so that the color monitor is operated under illumination light for observation. Color is reproduced, and the data after correction by the color adjustment device is given to the printer for color printing so that the printer can observe with the same color reproducibility as seen on the color monitor. Since it is possible to obtain a color print that can be reproduced, it is faithfully reproduced on the color monitor with the hue under the condition that the color of the printed matter is to be observed regardless of the change of the illumination condition and the spectral reflectance characteristic of the paper. In addition to being able to perform, it is possible to generate light that gives color stimulation under the illumination light to be used, so that the operator who operates the color adjustment operation means The color adjustment work can be performed in a state in which the visual sensation is adapted to the color stimulus received by the human under the illumination light, and therefore, the visual adjustment is performed in the state where the visual stimulus is also adjusted by the color adjustment device. This makes it possible to adjust colors more realistically.

Therefore, according to the color adjusting device of the present invention, the color of the printed matter can be confirmed on the monitor of the color adjusting device and adjusted to the desired hue regardless of the illumination light or the paper.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) In the first embodiment, it is possible to perform color adjustment on color image data used for printing, and to observe a printed matter on the color image data after the color adjustment. By performing color correction based on the spectral spectrum of the illumination light used for printing, the spectral reflectance characteristics of the paper used for printing, and giving this to a color monitor and displaying an image, the above-mentioned color adjustment is only performed arbitrarily, and the specified Enable to display on the monitor the observation environment and color reproduction of printed matter on paper. In addition, a color stimulus applied color stimulus value calculation means and an adaptation visual field presentation means are provided to calculate a color stimulus value that matches the adaptation state of the eyes of the operator who performs color adjustment with the adaptation state in the specified observation environment. By providing the color stimulating light, the adaptation state of the eyes of the operator is made the same as in the designated observation environment to ensure color reproducibility, which will be described in detail below.

FIG. 1 shows a block diagram of an embodiment according to the present invention. In the figure, 101 is a printed matter color adjustment unit, 103
Is a spectrocolorimeter, 104 is an illumination light spectrum storage unit, 10
6 is a color printer (hereinafter simply referred to as a printer), 1
Reference numeral 07 is an illumination light / paper characteristic correction unit, 108 is a forward applied color stimulus value calculation unit, and 109 is a color monitor.

Of these, the printed matter color adjusting unit 101 receives color image data as input, and when an image based on this color image data is printed out by the printer 106,
An image to be printed out is converted into a color signal so that desired color reproduction can be performed. Printed matter color adjustment unit 1
01 is provided with a color adjustment knob for independently controlling the gains of the C signal component, the M signal component, and the Y signal component with respect to the input color image data.

The printer 106 uses inks or toners of at least three colors of C (cyan), M (magenta), and Y (yellow), and color image data of each color component of C, M, and Y in pixel units. Then, the ink of the color corresponding to the color image data is printed on the recording paper at a ratio (color point area ratio) corresponding to the data value to reproduce the pixel.

The spectrocolorimeter 103 measures and outputs the spectral reflectance characteristic of the paper used for printing, and is provided in the paper feeding portion of the printer 106 and displays the spectral reflectance characteristic of the fed paper. It is a spectrophotometric means for measuring. The illumination light spectrum storage unit 104 stores the spectral characteristics of illumination light in various environments for observing printed matter. The spectral characteristics of the illumination light stored in the illumination light spectrum storage unit 104 can be freely designated and output by the operator's selection (designation of the type of illumination light).

The illumination light / paper characteristic correction unit 107 is for performing color correction based on the illumination light and the spectral reflectance characteristics of the paper used for printing, and is a spectrocolorimeter 103.
By receiving the spectral reflectance characteristic value of the sheet from the sheet and the spectral characteristic data of the illumination light from the illumination light spectrum storage unit 104, the printed matter color adjusting unit 101 is subjected to the characteristic correction according to the illumination light and the sheet. .

The color monitor 109 is a color display device using a cathode ray tube which receives the RGB signals obtained through the illumination light / paper characteristic correction unit 107 and displays a color image.

The forward application color stimulus value calculation unit 108 receives the spectral characteristic data of the illumination light from the illumination light spectrum storage unit 104, and obtains the forward application color stimulus corresponding to the color stimulus value of the illumination light to be used for observation. The color stimulus generation data for giving the color stimulus under the illumination light is calculated so as to be given to the operator, and the display area of the light giving the color stimulus can be formed around the inside of the screen of the monitor 109. I am doing it.

Next, the operation of the present apparatus having the above configuration will be described.

Color image data given as CMY3 primary color signals from the outside is input to the printed matter color adjusting unit 101,
Here, it is converted so that a desired color reproduction can be performed when it is output by the color printer 106. The converted signal is output to the illumination light / sheet characteristic correction unit 107 as a color image signal C′M′Y ′. Then, after being further corrected by the illumination light / sheet characteristic correction unit 107 so as to have a characteristic corresponding to the illumination light / sheet, it is given to the monitor 109 and displayed in color.

The printed matter color adjusting section 101 is provided with a color adjusting knob for independently controlling the gains of the C signal, M signal, and Y signal components. The operator who adjusts the color adjusts the color by operating the knob while viewing the image displayed on the monitor 109 so that the desired color is obtained.

The color image signal C'M'Y 'processed by the printed matter color adjusting unit 101 is supplied to the illumination light / paper characteristic correcting unit 10'.
7, the process for correcting the change in color of the printed matter is performed based on the spectral reflectance characteristic of the paper used for printing and the spectral characteristic of the illumination light of the environment for observing the printed matter.

By this processing, the color reproduction of the printed matter on the arbitrary observation environment and the arbitrary paper can be displayed on the monitor 109. For that purpose, the operator sets characteristic data corresponding to the type of illumination light to be used to 104 so that the observation environment to be used here and the color reproduction of the printed matter on the paper are performed on the monitor 109. Specify. Further, the operator sets the paper used for printing in the paper feed unit of the printer 106. The spectral reflectance characteristic of the paper is measured by the spectrocolorimeter 103.

As a result, the spectral characteristic to be used is given to the illumination light / sheet characteristic correcting section 107, and the spectral reflectance characteristic of the sheet used for printing is determined by the printer 1.
The measurement is performed by the spectrocolorimeter 103 provided in the paper feeding unit 06 and is sent to the illumination light / paper characteristic correcting unit 107.

By designating the illumination light by the operator who performs the color adjustment in this way, the spectral reflectance characteristic value under the illumination light to be used when observing the print is called from the illumination light spectrum storage unit 104. Is supplied to the illumination light / sheet characteristic correction unit 107, and the spectral reflectance characteristic of the sheet used for printing is automatically measured by the spectral colorimeter 103 provided in the sheet feeding unit of the printer 106 to illuminate the sheet. The color image signal C′M′Y ′ from the printed matter color adjusting unit 101 is printed by the printer 106 as a result of being sent to the light / sheet characteristic correcting unit 107 and performing correction corresponding to the illumination light / sheet characteristic. The printed matter can be observed with the same color reproducibility as seen with the illumination light under the actual observation environment. Since the color image signal C'M'Y 'adjusted by the printed matter color adjusting unit 101 is also given to the printer 106, when printed out by the printer 106, the printed matter is printed under the actual observation environment. When observed with the illumination light at, it is possible to observe with the same color reproducibility as seen on the monitor 109.

The forward applied color stimulus value calculation unit 108 receives the spectral characteristic data of the illumination light from the illumination light spectrum storage unit 104 and receives the forward applied color according to the color stimulus value of the illumination light to be used for observation. To give a stimulus to the operator,
The color stimulus generation data for giving the color stimulus under the illumination light is obtained, and the display area of the light giving the color stimulus is formed around the screen of the monitor 109.

Therefore, the operator sees the display area of the light which gives the color stimulus under the use illumination light, which is displayed around the inside of the screen of the monitor 109, and thereby the color stimulus received by the human under the use illumination light. Sight is adapted to. for that reason,
The visual sensation is adapted to the color stimulus that is also subjected to the color adjustment by the printed matter color adjusting unit 101, and the more realistic color adjustment can be performed on the screen of the monitor 109.

In this way, by adjusting the color adjusting knob of the printed matter color adjusting unit 101 so that the desired color shade is obtained on the monitor 109, the same color as the color under illumination light for observation is displayed on the monitor 109. Colors are reproduced, and the printer 1
From 06, a color print that can be observed with the same color reproducibility as seen on the monitor 109 can be obtained, so that the color of the printed matter can be observed regardless of changes in illumination conditions and spectral reflectance characteristics of the paper. It is possible to faithfully reproduce on the color monitor with the hue under the intended conditions.

Next, a method of correction processing performed by the illumination light / paper characteristic correction unit 107 will be described. The process described below is a process performed for one pixel in the image, and the same process is performed for all pixels in the image.

First, assuming that the amount of ink of each color of C, M and Y of a target pixel is (C ₀ , M ₀ , Y ₀ ), the spectral reflectance R ₀ (λ) of that pixel is given by the equation (1). You can ask.

[0035]

[Equation 1]Also, in the formula (1), R_paper(Λ) is a spectrophotometer
The spectral reflectance characteristics of the paper measured by 103
, S_C(C₀, M₀, Y₀), S_M(C₀, M ₀, Y
₀), S_Y(C₀, M₀, Y₀) Are respectively (C₀,
M₀, Y₀) Color points of C, M, and Y inks corresponding to
Area ratio.

Since this color point area ratio data is data unique to the printer, it is measured for each combination of (C, M, Y) and stored in the illumination light / sheet characteristic correction unit 107 as a lookup table LUT. Keep it. λ is the wavelength of light.

Spectral reflectance R _{0 of} the pixel calculated by the equation (1)
(Λ) is converted into RGB signals (R, G, B) to be output to the monitor 109 according to the equation (2).

[0038]

[Equation 2] Further, in Expression (2), S (λ) is the spectral characteristic of the illumination light in the environment for observing the printed matter, which is called from the illumination light spectrum storage unit 104. In addition, each integration is performed within the visible wavelength range.

The output signals (C ', M', Y ') from the printed matter color adjusting unit 101 are also sent to the printer 106 at the same time, the color adjustment is completed, and the desired color reproduction is obtained on the monitor 109. Printing is performed at the specified stage.

FIG. 2 shows that when the color adjustment of image data is performed,
Monitor 1 for checking the color reproduction of images when printed
Fig. 10 shows a schematic front view of 09. Monitor 109
Is composed of a cathode ray tube (color cathode ray tube, CRT), and the adaptation field presenting section 2 is provided on the outer peripheral portion of the effective display range of the CRT.
02 is provided, and the central portion is used as a display area 203 for an image to be subjected to color adjustment.

The adaptive visual field presenting unit 202 presents the forward applied color stimulus corresponding to the color stimulus value obtained by the forward applied color stimulus value calculation unit 108. By this color stimulus, the adaptation state of the eyes of the operator who performs the color adjustment is brought close to the adaptation state in the environment in which the printed matter is actually observed. Adaptive visual field presentation unit 20
The shape of No. 2 is not limited to the shape shown in FIG.
May be divided into left and right or upper and lower parts, and each may be used as an adaptation visual field presentation unit 202 and an image display area 203.

The forward applied color stimulus value calculation unit 108 calculates the forward applied color stimulus value based on the spectral characteristic of the illumination light sent from the illumination light spectrum storage unit 104.
The adaptation color stimulus values (R ′, G ′, B ′) are calculated according to the equation (3).

[0043]

[Equation 3] Further, S (λ) in Expression (3) is the spectral characteristic of the illumination light in the environment for observing the printed matter, which is called from the illumination light spectrum storage unit 104. In addition, each integration is performed within the visible wavelength range. Furthermore, when calculating the forward applied color stimulus value, the spectral reflectance characteristic of the paper used for printing, which is measured by the spectrocolorimeter 103, may be taken into consideration.

FIG. 4 is a diagram showing a modification of the display example of the adaptation visual field presenting section on the screen of the monitor 109. In the present modification, the adaptation stage that displays the normal applied color stimulus presentation unit displayed on the screen of the monitor 109 using the entire screen, and the normal applied color stimulus presentation unit that is cut to perform color adjustment and only the image is displayed. The color adjustment stage to be brought to the display state of is switched and used in time.

This switching is automatically performed at regular time intervals so that the adaptation state of the eyes of the operator who performs color adjustment does not adapt to the illumination of the environment where color adjustment is performed. It takes a few seconds to a minute to respond to the adaptation action, but since the action of adding and accumulating intermittent stimuli works in the visual system, an adaptation stage is performed at a speed of several Hz to several tens Hz. The color adjustment stage may be switched.

When the monitor 109 using the NTSC color video signal is used, it is preferable to switch at 30 Hz corresponding to the frame interval. At this time, it is desirable that the average brightness of the screen does not change between the adaptation stage and the color adjustment stage, so calculate the average brightness of the entire image that is the target of color adjustment and match the brightness of the forward applied color stimulus value to this value. It is good to let

Further, this switching may be performed in conjunction with the operation of the color adjustment knob. That is, the monitor 109
In the process of operating the color adjustment knob, color conversion processing of the image is performed, so it functions as the screen (adaptation stage) of the forward applied color stimulus presentation unit, and the operation of the color adjustment knob is completed, and the image is displayed. When the color conversion process is completed, it functions as an image display screen (color adjustment stage) for color adjustment.

Another modification of the adaptive visual field presenting section 202 is shown in FIG.
Shown in. In this example, the adaptive visual field presenting unit 202 is not displayed and used as an image on the monitor screen but is used as an independent illuminating device as the adaptive visual field presenting apparatus 202A, and is provided around the monitor 109.

FIG. 6 is an upper sectional view showing a specific structure of the adaptive visual field presenting apparatus 202A. Adaptive visual field presentation device 202
A includes three white light sources 601, three filters 602 corresponding to R, G, and B colors, and a diffusion plate 603.

The three filters 602 are respectively

[0051]

[Equation 4] It has the spectral transmittance characteristic shown by.

By using the forward applied color stimulus values (R ', G', B ') obtained by the forward applied color stimulus value calculation unit 108, R,
The brightness of the Japanese color light source 601 corresponding to each of the G and B colors is controlled, and the light of the forward application field is formed by the additive color mixture (a method of reproducing the color by the ratio of the three primary colors R, G, and B used).

Human vision has a characteristic that the same object looks the same color even if the illumination light changes. This is called color constancy. This is because the human visual processing system has a function of canceling the spectral characteristic of the illumination light and extracting only the spectral reflectance characteristic of the object, and this characteristic maintains color constancy. Be done.

However, in the case where the spectral radiation characteristic of the illumination light is a spike-shaped spectrum that is biased to a specific very narrow wavelength region, as seen in fluorescent lamps and mercury lamps, the color constant is constant. Sexual function may be impaired.

Similarly, when the spectral reflectance characteristic of the ink used for printing has a spike-shaped spectrum, the function of color constancy may be similarly impaired.

In the color adjusting device according to the present invention, color constancy is not maintained even in human visual characteristics, as in the case where the spectral characteristics of illumination light or ink have a spike-like spectrum as described above. When performing color adjustment while checking the color of printed matter under various conditions on the monitor,
It is particularly suitable.

The above is the color adjusting device capable of adjusting the color of the printed matter on the monitor while confirming the color reproduction of the printed matter in advance. A color adjustment device that corrects and outputs the color image data used according to the operation amount of the color adjustment operation device, a colorimeter that measures the spectral reflectance characteristics of the paper used for printing, and an illumination light used when observing the printed matter. The color correction of the image on the color monitor is performed by using the illumination light spectrum storage device that stores the spectral spectrum of, and the spectral data of the illumination light from this illumination light spectrum storage device and the measurement value from the colorimeter. A color sequence applied color stimulus value calculating device for obtaining a color sequence applied color stimulus value using the spectral data of the illumination light from the illumination light spectrum storage device, and this color Which was more configuration and adaptation field presentation means for generating a color sequential applications color stimulus determined applications color stimulus value calculation unit, so that the hue of the object on a color monitor,
By operating the color adjustment operation means of the color adjustment device, a color similar to the color under illumination light used for observation is reproduced on the color monitor, and the data corrected by the color adjustment device is given to the printer. By performing color printing with the printer, a color print that can be observed with the same color reproducibility as seen on a color monitor can be obtained from the printer, so changes in lighting conditions and changes in the spectral reflectance characteristics of the paper can be obtained. Regardless of the color, it will be possible to faithfully reproduce the color of the printed matter on the color monitor under the conditions to observe the color of the printed matter, and to use the light that gives the color stimulus under the illumination light to be used. Because it can occur
An operator who operates the color adjustment operating means can perform color adjustment work in a state in which his or her eyes are adapted to the color stimulus received by the illuminating light used, and therefore the color adjustment by the color adjusting device is also performed. The visual sensation is adapted to the stimulus, and the color adjustment can be made more realistically.

In the above, the spectral reflectance characteristic of the paper is determined by the spectrocolorimeter provided in the paper feeding section of the printer.
A configuration in which spectral reflectance characteristics of a recording paper that may be used are prepared in advance and can be arbitrarily selected and used without using a colorimeter is also considered. Therefore, such a case will be described below as a second embodiment.

(Second Embodiment) FIG. 3 shows a second embodiment according to the present invention.
3 shows a block diagram of an embodiment.

In this embodiment, as a means for obtaining the spectral reflectance characteristic of the sheet to be printed, instead of the spectrocolorimeter 103, a sheet characteristic storage section 302 storing various spectral reflectance characteristic data of the sheet, and The color adjusting device includes a sheet characteristic selecting unit 301 for selecting which of the spectral reflectance characteristic data to be used.

The paper characteristic selection unit 301 is composed of a sensor for detecting the amount of reflected light of the paper provided in the paper feeding unit of the printer 106 and a selection unit. The selection unit judges the paper to be used based on the output of this sensor, It has a function of selecting the corresponding spectral reflectance characteristic from the sheet characteristic storage unit 302.

The sheet characteristic storage unit 302 holds the spectral reflectance characteristics of various sheets that are supposed to be used. The sheet characteristic selection unit 301 determines the sheet to be used based on the output of the sensor provided in the sheet feeding unit of the printer 106, and determines the corresponding spectral reflectance characteristic as the sheet characteristic storage unit 302.
And sends it to the illumination light / sheet characteristic correction unit 107.

By holding the spectral reflectance characteristics of various types of paper, printed matter depending on the spectral reflectance characteristics of the paper can be used without using an expensive sensor such as a spectral colorimeter (spectral colorimeter). The change in color can be calculated. Also,
The paper characteristics may be selected manually by an operator who performs color adjustment.

(Third Embodiment) Next, the original image data adjusted so that a desired color reproduction is obtained under the standard illumination light source is used so that the same color reproduction can be obtained under different illumination light. A third embodiment will be described as an embodiment in which the adjustment can be made to

FIG. 7 shows a block diagram of a third embodiment according to the present invention.

The color adjusting apparatus according to the present embodiment uses original image data adjusted so that desired color reproduction can be obtained under a standard illumination light source (for example, D ₆₅ ) under different illumination lights. This is an apparatus that adjusts so as to obtain the same color reproduction, and has an adaptation visual field pattern storage unit 701, a standard illumination light spectrum storage unit 704, an illumination light correction unit 707, in addition to the configuration of FIG.
Standard light order application color stimulus value calculation unit 708, standard monitor 70
9. A standard illumination light correction unit 710 is provided and configured.

Of these, the adaptive visual field pattern storage unit 7
Reference numeral 01 stores, as data, the spectral reflectance characteristic, size, and arrangement relationship of a forward application visual field patch as shown in FIG. 9, which will be described later. The standard illumination light spectrum storage unit 704 stores
It holds data on the spectral characteristics of standard illumination light.

The illumination light correction unit 707 illuminates the environment for observing the printed matter with respect to the corrected image data from the printed matter color control unit 101 based on the illumination light data provided from the illumination light spectrum storage unit 104. The standard light order applied color stimulus value calculation unit 708 is configured to perform correction processing so as to correspond to the color change of the printed matter based on the spectral characteristic of light, and the adaptive visual field pattern storage unit 701 and the standard illumination light spectrum storage unit 708. The forward application color stimulus value under standard light is calculated based on the data from 704.

The standard illumination light correction unit 710 uses the spectral characteristics of the standard illumination light called from the standard illumination light spectrum storage unit 704 to display the image based on the image data CMY displayed on the standard monitor 709 under the standard illumination light. The image data CMY is corrected so that the color tone of the printed matter in
The standard monitor 70 converts the image signal into a GB image signal.
Reference numeral 9 denotes a display device using a color cathode ray tube, which receives an image signal corrected by the standard illumination light correction unit 710 and displays an image.

As will be described later, the standard monitor 709 is composed of a CRT, a forward application image presenting section 902 is provided on the outer peripheral portion of the effective display range of the CRT, and a display area 803 whose central portion displays an image to be adjusted. Work as.

The operation of the present apparatus having such a configuration will be described below. However, since the description of the same component parts as in FIG. 1 has already been given here, refer to the previous one and newly add The operation of the added components will be mainly described.

First, the original image data (C, M,
Y) is given to the printed matter adjusting unit 101 and is also sent to the standard illumination light correction unit 710.
The standard monitor 7 displays the color of the printed matter under the standard illumination light.
Processing for displaying on 09 is performed. The spectral characteristic of the standard illumination light necessary for this processing is called from the standard illumination light spectrum storage unit 704, and the standard illumination light correction unit 71 is called.
Sent to 0.

The correction process performed by the standard illumination light correction unit 710 is performed by the method described below. The process described below is a process performed for one pixel in the image, and the same process is performed for all pixels in the image.

First, the amount of ink of each color of C, M and Y of the pixel of interest when printed by the printer is (C ₀ , M ₀ , Y).
₀ ), the spectral reflectance R ₀ (λ) of the pixel can be calculated by the equation (4).

[0075]

[Equation 5] S _C (C ₀ , M ₀ , Y ₀ ), S _M (C ₀ , M ₀ ,
_{Y 0), S Y (C} 0, M 0, Y 0) are each _{(C 0, M 0, Y} 0) corresponding to C (cyan), M (magenta), Y (yellow) color of each color ink The point area ratio. Since this color point area ratio data is data unique to the printer, it is measured for each combination of (C, M, Y) and stored in the standard illumination light correction unit 710 as a lookup table LUT. λ is the wavelength of light.

The spectral reflectance R _{0 of} the pixel calculated by the equation (4)
(Λ) is converted into RGB signals (R, G, B) to be output to the standard monitor 709 according to the equation (5).

[0077]

[Equation 6] S (λ) is the spectral characteristic of the standard illumination light called from the illumination light spectrum storage unit 704. In addition, each integration is performed within the visible wavelength range.

At the same time, the original image data input to the printed matter color adjusting unit 101 is printed by the printer 106.
Is converted so that a desired color reproduction can be performed when the image is output. The printed matter color adjusting unit 101 includes a C signal, an M signal, and a Y signal.
A color adjustment knob for independently controlling the signal and each gain is provided.

The operator who performs color adjustment is the monitor 109.
The image displayed on the standard monitor 709 and the image displayed on the standard monitor 709 are compared with each other, and the knobs are operated so that the colors are the same.

The color image data (C ', M', Y ') processed by the printed matter color adjusting unit 101 is supplied to the illumination light correcting unit 70.
7, the process for correcting the change in the color of the printed matter is performed based on the spectral characteristic of the illumination light of the environment for observing the printed matter. By this processing, the color reproduction of the printed matter in an arbitrary observation environment can be displayed on the monitor 109.

The spectral characteristic of the illumination light of the environment for observing the printed matter is specified by the operator himself who actually performs the color adjustment work. The illumination light data designated by the operator is called from the illumination light spectrum storage unit 104 and sent to the illumination light correction unit 707 to be illuminated light correction unit 707.
On the basis of the given illumination light data, the corrected image data from the printed matter color control unit 101 changes the color of the printed matter based on the spectral characteristic of the illumination light of the environment in which the printed matter is observed. Performs a process for performing various corrections.

The correction process performed by the illumination light correction unit 707 is performed by the method described below. The process described below is a process performed for one pixel in the image, and the same process is performed for all pixels in the image.

First, assuming that the amount of ink of each color of C, M, and Y of the target pixel is (C ₀ , M ₀ , Y ₀ ), the spectral reflectance R ₀ (λ) of that pixel is given by equation (6). You can ask.

[0084]

[Equation 7] S _C (C ₀ , M ₀ , Y ₀ ), S _M (C ₀ , M ₀ ,
Y ₀ ), S _Y (C ₀ , M ₀ , Y ₀ ) are the color point area ratios of the C, M, and Y color inks corresponding to (C ₀ , M ₀ , Y ₀ ), respectively. Since this color point area ratio data is data unique to the printer, it is measured for each combination of (C, M, Y) and stored in the standard illumination light correction unit 707 as a lookup table. λ is the wavelength of light.

The spectral reflectance R _{0 of} the pixel calculated by the equation (6)
(Λ) is converted into RGB signals (R, G, B) to be output to the monitor 109 according to the equation (7).

[0086]

[Equation 8] S (λ) is a spectral characteristic of the illumination light when the printed matter is observed, which is called from the illumination light spectrum storage unit 104. In addition, each integration is performed within the visible wavelength range.

FIGS. 8A and 8B are schematic front views of the monitor 109 and the standard monitor 709. The monitor 109 and the standard monitor 709 are configured by a cathode ray tube (color cathode ray tube, hereinafter referred to as CRT), and forward application image presenting units 502A and 902 are provided on the outer peripheral portion of the effective display range of the CRT, respectively, and a central portion. Is used as the display areas 203 and 803 of the image to be color-adjusted.

Forward application image presentation unit 502A of the monitor 109
Is a part of the effective display range of the CRT, is given the forward application image data obtained by the forward application color stimulus value calculation unit 108, and presents the forward application field of view. The operator's vision adapts to this application field of view, and an adaptation state with illumination light when observing the printed matter is formed.

On the other hand, the normal application image presenting unit 902 of the standard monitor 709 is supplied with the normal application image data obtained by the standard light normal applied color stimulus value calculating unit 708, and the adaptation field is adapted to the standard illumination light. A state is formed.

Next, how to create the forward application image data will be described.

The forward applied visual field in this embodiment is realized by an image in which square patches of various sizes having various spectral reflectance characteristics are randomly combined, as shown in FIG. The spectral reflectance characteristics, size, and arrangement of each patch are held in the adaptive visual field pattern storage unit 701. The spectral reflectance characteristics of each patch should be substantially achromatic when the characteristics of all patches are averaged.

The stimulus value calculation process in the forward applied color stimulus value calculation unit 108 based on the data from the adaptation visual field pattern storage unit 701 is performed as follows. For each patch, based on the spectral reflectance characteristic sent from the adaptation visual field pattern storage unit 701 and the spectral characteristic of the illumination light sent from the illumination light spectrum storage unit 104, the forward applied color stimulus is calculated according to the equation (8). (R ', G', B ') is calculated.

[0093]

[Equation 9] S (λ) is the spectral characteristic of the illumination light in the environment for observing the printed matter, which is called from the illumination light spectrum storage unit 104. R _patch (λ) is the adaptive visual field pattern storage unit 70.
It is a spectral reflectance curve of the patch sent from 1. In addition, each integration is performed within the visible wavelength range.

The R ', G', and B'are combined with the patch size and arrangement information sent from the adaptation visual field pattern storage unit 701 to form a forward application image, which is displayed on the CRT as a signal for display on the monitor 109. Sent to.

In the standard light order application color stimulus value calculation unit 708,
The standard illumination light spectrum storage unit 7 stores S (λ) in Expression (8).
Replaced with the spectral characteristics of standard illumination light called from 04,

[0096]

[Equation 10] Is replaced with the spectral characteristics of the R, G, and B original stimuli of the standard monitor 709, and the forward application color stimulus values (R ′, G ′, B ′) are calculated by the same calculation.

The forward applied visual field is not limited to the combination of square patches, but may be different as long as the area, arrangement, and spectral reflectance characteristics change randomly and the average of the entire adaptive visual field is achromatic. It may be a pattern.

The output signals (C ', M', Y ') from the printed matter color adjusting unit 101 are also sent to the printer 106 at the same time, the color adjustment is completed, and the same color as the standard monitor 709 is displayed on the monitor 109. Printing is performed when the reproduction is obtained.

As described above, according to the third embodiment, by using the original image data adjusted so that a desired color reproduction can be obtained under the standard illumination light source, another illumination different from the standard illumination light source is used. It can be adjusted under light to obtain the same color reproduction as under standard illumination sources. Therefore, by using the color adjusting apparatus according to the present embodiment, it is possible to obtain a printed matter that exhibits the same color reproduction as that realized under a certain illumination light even when the illumination light changes. .

The present invention is not limited to the above-described embodiments, but can be modified and implemented as appropriate without departing from the scope of the invention.

[0101]

As described above in detail, according to the present invention, when a printed matter is printed by using a color printer or the like using color image data, color reproduction of the printed matter due to illumination light or spectral characteristics of the paper is performed. You can correct the change and check it on the monitor in advance, so you can adjust the color while looking at the monitor without making a proof print.
It is possible to provide a color adjusting device that makes it possible to obtain a printed matter having desired color reproducibility.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of the present invention,
The block diagram which shows the whole structure of the 1st Example of this invention.

FIG. 2 is a diagram for explaining an embodiment of the present invention,
FIG. 3 is a schematic front view of the monitor 109 for confirming color reproduction of an image when printed when performing color adjustment of image data.

FIG. 3 is a diagram for explaining an embodiment of the present invention,
The block diagram which shows the whole structure of 2nd Example of this invention.

FIG. 4 is a diagram for explaining an embodiment of the present invention,
The figure for demonstrating the modification of the example of a display of the adaptation visual field presentation field displayed on the monitor screen applied to this invention.

FIG. 5 is a diagram for explaining an embodiment of the present invention,
The figure which shows the independent adaptation visual field presentation apparatus for giving an adaptation visual field presentation field applied to this invention.

FIG. 6 is a diagram for explaining an embodiment of the present invention,
The schematic diagram showing the example of concrete composition of the adaptation visual field presentation device of the present invention.

FIG. 7 is a diagram for explaining an embodiment of the present invention,
The block diagram which shows the whole structure of 3rd Example of this invention.

FIG. 8 is a diagram for explaining an embodiment of the present invention,
The figure which shows the front schematic diagram of the monitor 109 and standard monitor 709 applied to the 3rd Example of this invention.

FIG. 9 is a view for explaining the embodiment of the present invention,
The figure which shows an example of the forward application visual field used by the 3rd Example of this invention.

[Explanation of symbols]

 Reference numeral 101 ... Printed matter color adjustment section 103 ... Spectral colorimeter 104 ... Illumination light spectrum storage section 106 ... Printer 107 ... Illumination light / paper characteristic correction section 108 ... Normal applied color stimulus value calculation section 109 ... Monitor 202 ... Adaptation visual field presentation section 202A Adaptation visual field presentation device 203, 803 ... Image display area 301 ... Paper characteristic selection unit 302 ... Paper characteristic storage unit 601 ... White light source 602 ... Filter 603 ... Diffusion plate 701 ... Adaptation visual field pattern storage unit 704 ... Standard illumination light spectrum storage Part 707 ... Illumination light correction unit 708 ... Standard light order applied color stimulus value calculation unit 709 ... Standard monitor 710 ... Standard illumination light correction unit

Claims (1)

[Claims] 1. A color monitor for displaying a color image according to color image data, and a color adjustment operation means for giving a color adjustment operation amount.
A color adjusting unit that corrects and outputs color image data used for printing according to the operation amount of the color adjusting operating unit, a colorimeter that measures the spectral reflectance characteristics of the paper used for printing, and an illumination used when observing the printed matter. An illumination light spectrum storage unit that stores a spectrum of light, and a spectrum of the illumination light from the illumination light spectrum storage unit and a measurement value from the colorimeter are used to display an image on the color monitor. A correction means for performing data correction for color correction, a color order applied color stimulus value calculation means for obtaining a color order applied color stimulus value using the spectral data of the illumination light from the illumination light spectrum storage device, and this color order A color adjusting device comprising: an adaptive visual field presenting means for generating light of applied color stimulus obtained by the applied color stimulus value calculating means.