JPH10322566A - Image processor and image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processor by which colors can be stably repro duced between the devices different in color reproducing characteristics even under different environmental beams. SOLUTION: Scanner RGB signals are converted to XYZ signals based on data in a scanner profile 22. The XYZ signals are converted to standard RGB signals based on data in a standard monitor profile 24. Corresponding to the characteristics of existent monitor designated from an operator through a monitor designating device 12 and the color characteristics of surrounding environmental light designated through an environmental light densignating device 13, the standard monitor RGB signals are corrected into monitor RGB signals for the existent monitor by a color space correction part 11 and displayed on the monitor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, an image processing apparatus and an image processing method for converting a color space of input image data.

[0002]

2. Description of the Related Art In recent years, with the spread of personal computers, for example, anyone can create a document in which color photographs read by a scanner or the like are laid out, or create color graphics and print out from a printer. It's getting easier.

[0003] Generally, an operator operates a computer through a software copy display device (hereinafter referred to as a monitor) such as a CRT. Therefore, when performing the above operation, it is necessary to confirm that the color photograph as the document to be scanned matches the color of the image displayed on the monitor or the color of the graphic created on the monitor screen. And the color of the image to be printed out are required to match.

[0004] However, the color reproduction characteristics of a monitor and a scanner, or of a monitor and a printer, are significantly different.
Matching these is usually very difficult.

[0005] For the above reasons, a color management system (hereinafter referred to as a CM) has been attracting attention recently.
S). One example is shown in FIG.

FIG. 11 is a diagram showing an example of a system configuration of an image processing apparatus provided with a CMS as a conventional example. The image data obtained by reading an image on a document with a scanner is displayed on a monitor. The configuration is shown.

In FIG. 1, a computer 101 as an image processing apparatus and a scanner 102 are connected to a SCSI (Small Computer).
It is connected via a general-purpose interface such as a System Interface.

The CPU 120 of the computer 101 controls the entire color management system according to the following software group. The computer 101 reads an image on a document on the scanner 108 by driver software 103 that controls the scanner 102. The image read by the scanner 102 is displayed on the monitor 108 by the image display software 104 for displaying the image on the monitor 108. At this time, each software is an OS (Operating System) 1 controlled by the CPU 120.
Operating under the OS 05, the image display software 104
It requests the display of the image on the monitor 108 to the monitor 105. The OS 105 writes the image data received from the image display software 104 to a VRAM (Video-RAM) 106 which is a screen storage device for monitor display. VRAM
The image data written in 106 is the monitor driver 1
07 is displayed on the monitor 108. Here, the monitor driver 107 converts a digital signal on the VRAM 106 into an analog signal to generate a raster signal, and supplies the raster signal to the monitor 108.

Further, in the conventional example of FIG. 11, not only the image data received from the image display software 104 as described above is displayed on the monitor 108 as it is, but also the OS 10
Reference numeral 5 can convert image data received from the image display software 104 into data for monitor display using the CMS 109 and display the data.

That is, the scanner 1 is included in the CMS 109.
Scanner profile 110 describing the color characteristics of 02
And a monitor profile 111 describing the color reproduction characteristics of the monitor 108 are stored in advance. OS 105 is
The image data received from the image display software 104 is subjected to color signal conversion using these profiles, and is then displayed on the monitor 108.
02 can be reproduced on the monitor 108 in the same color as the color read on the original (note that when the color displayed on the monitor 108 is reproduced on a printer output (not shown), Similar color signal conversion may be performed using the profile 111 and a printer profile (not shown)). That is, color matching between different devices is realized. One such CMS is Apple's C
olorSync (R) and MicroSoft's ICM (TM) are known.

[0011]

However, in the above-mentioned conventional example, since the color reproduction characteristics are different for each device, it is necessary to prepare a profile for each device. In particular, since there are many types of monitors for computers and the color reproduction characteristics are different for each of them, it is not realistic to prepare profiles for all of them.

When a profile for a certain monitor exists, the image data converted by the CMS can reproduce the same color as the image on the document only when displayed on the monitor. However, when the image data is displayed on another monitor, correct color reproduction cannot be obtained.

Further, since the data read by the scanner at this time is converted for display on a monitor, if this image data is to be saved as a file 112 in a storage device such as a hard disk on a computer, the converted data is not stored. Will be saved. That is, even if the scanner is the same, if different monitor profiles are used by using different monitors, the file 1
12 are different from each other.

When graphic data such as CG created on a computer is printed out using a monitor profile of a monitor used at that time, colors on the monitor can be reproduced on recording paper. However, if the same graphic data is printed using a monitor profile of another monitor, different colors will be printed out even though the output device (printer) is the same. That is, there is an inconvenience that the print result differs depending on the type of the monitor used.

Further, it has been clarified that the appearance of colors on the monitor also changes depending on ambient environmental light when observing the monitor. This is because, considering the general computer usage environment, the document to be scanned is observed under a light source that illuminates the room (hereinafter, ambient light),
The image on the monitor will observe the color that is emitting light. Therefore, even with the same monitor, the appearance of the color of the original changes according to the characteristics of the ambient light. In addition, the appearance of colors on the monitor also changes due to the characteristics of environmental light due to the partial adaptation effect of human vision.

As for the characteristics of the ambient light, mainly the color temperature greatly affects the appearance of the color. For example, the color appearance on a monitor having a white point of color temperature 6500K and the color temperature 6500K
If the color temperature of the ambient light matches the color temperature of the original under the ambient light, but the color temperature of the ambient light is changed to a 4000 K white fluorescent lamp used in ordinary offices, However, even if the colors of the monitors are the same, the appearance of the colors cannot be matched, and the colors on the monitor are observed to be much bluer than the colors on the document.

In order to eliminate such inconvenience, it is also possible to prepare in advance several types of environmental light characteristics when an observer observes a monitor and a document, and create a monitor profile for each characteristic. It is. However, in this case, a profile corresponding to the characteristic of the ambient light is further added to the profile set for each type of monitor, and considering the memory resources necessary for preparing and storing the profile, it is realistic. is not.

Accordingly, an object of the present invention is to provide an image processing apparatus and an image processing method capable of performing stable color reproduction between devices having different color reproduction characteristics even under different ambient light sources.

[0019]

To achieve the above object, an image processing apparatus according to the present invention has the following configuration.

That is, an image processing apparatus for converting and outputting a color space of input image data, wherein an image signal input from an input device is converted based on color space characteristic information of the input device stored in advance. First color space conversion means for converting into an image signal of a device-independent color space; and an image signal output from the first color space conversion means, which is stored in advance in a color space characteristic information of a standard output device. A second color space conversion means for converting the image signal into an image signal of a color space dependent on the standard output device, a first specification means for specifying a color reproduction characteristic of the output device, and a color characteristic of ambient environmental light. And a correction unit that corrects the image signal output from the second color space conversion unit according to the color reproduction characteristics specified by the first and second specification units. Preparation It is characterized in.

For example, an image signal input from the input device is an RGB signal, an image signal in a color space independent of the device is an XYZ signal, and an image signal in a color space dependent on the standard output device is the standard signal. It may be an RGB signal of an output device.

Further, for example, the correction means performs inverse gamma correction, matrix conversion, and gamma correction of the image signal in the color space depending on the standard output device, thereby performing the image signal in the color space depending on the output device. Should be corrected.

Preferably, the first designating means includes first measuring means for measuring a color reproduction characteristic of the output device, and the output device is measured based on a measured value from the first measuring means. The color reproduction characteristics of

Preferably, the second designating means includes a second measuring means for measuring ambient light, and the color reproduction of the output device is performed based on a measurement value from the second measuring means. You may want to generate a property.

Alternatively, in order to achieve the above object, an image processing method of the present invention has the following configuration.

In other words, there is provided an image processing method for converting a color space of input image data and outputting the converted image data, wherein an image signal input from an input device depends on the device based on characteristic information of the color space of the input device. A first color space conversion step of converting the image signal selected in the first color space conversion step into an image signal of a color space not to be converted, based on the color space characteristic information of the standard output device. A second color space conversion step of converting the image signal into an image signal of a color space dependent on the image signal, and an image signal obtained in the second color space conversion step.
And a correction step for correcting according to the color reproduction characteristics of the output device and / or the color characteristics of ambient environmental light.

For example, an image signal input from the input device is an RGB signal, an image signal of a color space independent of the device is an XYZ signal, and an image signal of a color space dependent on the standard output device is the standard output. It may be an RGB signal of the device.

In the correcting step, for example, the image signal in the color space dependent on the standard output device is subjected to inverse gamma correction, matrix conversion, and gamma correction to obtain the image signal in the color space dependent on the output device. Should be corrected.

That is, a color processing method for performing a color matching process according to an output device, wherein color data subjected to a color matching process according to a source profile and a standard profile corresponding to a source device via an operating system. Input, input information about the color characteristics of the output device, perform inverse processing of the processing based on the standard output profile on the color data subjected to the color matching processing, and perform color processing according to the monitor characteristics. It is characterized by the following.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the image processing apparatus according to the present invention will be described in detail with reference to the drawings.

[First Embodiment] FIG. 1 shows a first embodiment of the present invention.
1 is a system configuration diagram of an image processing apparatus including a CMS as an embodiment of FIG.

Referring to FIG. 11, a configuration different from that of FIG. 11 will be described. A color space correction unit 11 for performing a color space correction process on the color signal data stored in the VRAM 106 and the color of the monitor 108 actually used. A monitor designation device 12 for designating reproduction characteristics and an ambient light designation device 13 for designating characteristics of ambient environmental light are provided (details will be described later).

Here, it goes without saying that the color space correction section 11 may be provided on a video circuit of the computer 101, or may be implemented as an external circuit, a processing circuit inside the monitor 108, or the like. Also, the monitor designation device 12
Can be realized by software on the computer 101 or an external switch box or the like.

In the present embodiment, a "standard monitor profile 24" indicating the color reproduction characteristics of a virtual standard monitor, instead of the profile representing the color reproduction characteristics of the monitor 108 being used, is stored in the monitor profile in advance. (Details will be described later).

When the operator specifies the color characteristics of the monitor currently used from the monitor specifying device 12 and specifies the characteristics of the surrounding ambient light from the ambient light specifying device 13, the OS 10
5 is a color space correction unit 1 according to the input designation information.
Set the parameter of 1. The parameters of the color space correction unit 11 may be directly rewritten by the designation of the monitor designation device 12 without the intervention of the OS 105.

Hereinafter, the operation of the image processing apparatus of the present embodiment having the above system configuration will be described.

In general, the color reproduction characteristics of a color monitor include, for example, R, G,
It can be described by three basic characteristics: a color development characteristic of the phosphor of the B3 primary color, a gamma characteristic indicating the linearity between the voltage applied to the electron gun and the emission luminance, and a color temperature of the white point. Since these characteristics vary depending on the monitor manufacturer, type, size, and the like, it is necessary to create profile data based on these for each monitor. The environmental light characteristics that affect the appearance of colors on the monitor can be defined by the color temperature (correlated color temperature) of the illumination light source used in the surrounding environment.

FIG. 2 is a view for explaining the color conversion processing by CMS as the first embodiment of the present invention.

In the figure, an RGB signal (scanner RGB signal) of an image on a document read by the scanner 102 is first converted into a device-independent color space by a color space converter 1 (21), for example, a CIE-XYZ signal. Is converted to The scanner profile 22 includes the scanner 102
Are stored in advance, and color space conversion is executed based on this data.

Next, the XY obtained by the conversion to the color space
The Z signal is output to the standard monitor RGB by the color space conversion unit 2 (23).
Converted to a signal. The standard monitor profile 24 includes
The color reproduction characteristic data of the standard monitor is stored in advance,
Conversion is performed based on this data. In the present embodiment, a virtual standard monitor profile is set in the standard monitor profile 24 instead of the profile of the monitor used by the operator.

As an example of the standard monitor and the standard observation environment conditions, a virtual monitor having the following characteristics is assumed.

(1) Chromaticity coordinates of three-color phosphor (CIE-x)
(y chromaticity coordinates) Red: x = 0.64, y = 0.33 Green: x = 0.30, y = 0.60 Blue: x = 0.15, y = 0.06 (2) Emission luminance Gamma characteristics 2.2 for each of red, green and blue (3) White point color temperature 6500K (equivalent to D65 standard light source) (4) Ambient light color temperature 6500K (equivalent to D65 standard light source) Although the color temperature of ambient light is the same as the white point of the monitor, this is an ideal state and does not necessarily represent the characteristics of a real monitor.

Assuming that a monitor having the above characteristics exists, this color reproduction characteristic data is
The XYZ signal from the color space conversion unit 1 (21) is converted into a monitor RGB signal by the color space conversion unit 2 (23). In order to convert the RGB signals to be displayed on the virtual monitor having the characteristics (1) to (3), X
The following conversion may be performed on the YZ signal.

First, (1) the chromaticity coordinates (CI) of the three-color phosphor
In consideration of (E-xy chromaticity coordinates), (3) the color temperature of the white point, and (4) the color temperature of the ambient light, the XYZ signal is converted into R ′, G ′, and B ′ according to equation (5).

[0045]

(Equation 1)

(5) Next, (2) R ′,
G ′, B ′ are converted into R, G, B by the following equation.

R = 255 × (R ′ / 255) ＾ 1 / 2.2 G = 255 × (G ′ / 255) ＾ 1 / 2.2 B = 255 × (B ′ / 255) ＾ 1/2. 2 (6) Here, the R, G, and B signals are each represented by an 8-bit integer value (note that ＾ is an operator representing a power-on operation). The R, G, and B signals obtained in this manner are converted into R, G, and G signals for displaying correct colors on a virtual standard monitor having the characteristics of (1) to (3) under the standard environment specified in (4). , B signals.

Next, the characteristics of the monitor actually used will be considered. If the characteristics of the monitor actually used are the same as the characteristics (1) to (3) and (4) of the virtual monitor, the R, G, and B signals obtained by Expression (5) are displayed as they are. I just need. However, the characteristics are usually different for each monitor.

Now, the characteristics of the actual monitor used are as follows:
It is assumed that the following (1 ′) to (3 ′) and the environmental condition is (4 ′).

(1 ') Chromaticity coordinates of three-color phosphor (CIE-
(xy chromaticity coordinates) Red: x = 0.60, y = 0.30 Green: x = 0.32, y = 0.58 Blue: x = 0.18, y = 0.08 (2 ′) Emission luminance (3 ') White point color temperature 6500K (equivalent to D65 standard light source) (4') Ambient light color temperature 4200K (equivalent to ordinary office white fluorescent lamp) In the conventional method, when a monitor having such characteristics is used, these conditions are set in the monitor profile of the CMS, and the following equations are used instead of the above equations (5) and (6). Equations (5 ′) and (6 ′) are executed to directly correct the XYZ signal to the monitor RGB signal for the actual monitor.

[0051]

(Equation 2)

.. (5 ′) R = 255 × (R ′ / 255) ＾ 1 / 1.8 G = 255 × (G ′ / 255) ＾ 1 / 1.8 B = 255 × (B ′ / 255) ＾ 1 / 1.8 (6 ′) On the other hand, in the present embodiment, the color space conversion unit 2 of the CMS 109
In (23), XY from the color space conversion unit 1 (21)
By performing the operations of Expressions (5) and (6) on the Z signal,
R, G, and B signals for a virtual standard monitor are required. Therefore, in the color space correction unit 11 of FIG. 1, (5 ′)
In order to generate monitor RGB signals for a real monitor obtained by executing the equations (6 ′) and (6 ′), the color space conversion unit 2 (2
The monitor RGB signal for the real monitor must be generated from the virtual standard monitor RGB signal from 3).

Therefore, in the present embodiment, the characteristics of the real monitor (1 ′) to (3 ′) are specified from the monitor specifying device 12 in FIG. 1, and the conditions of (4 ′) are specified from the ambient light specifying device 13. Set. Then, the color space correction unit 11 calculates appropriate parameters with reference to the characteristic data of the real monitor 108 set by the monitor specifying device 12, and uses the parameters to generate a virtual standard monitor RGB. The signal is corrected to a monitor RGB signal for the real monitor 108. The correction performed by the color space correction unit 11 will be described with reference to FIG.

FIG. 3 is a diagram for explaining color conversion in the color space correction unit 11 according to the first embodiment of the present invention.
2 shows details inside the color space correction unit 11 of FIG. 1.

In the figure, the input of FIG. 3 is the VRA of FIG.
RGB signal from M, as described above, CMS
109 by the color space conversion unit 2 (23).
It has been corrected to a GB signal.

In the inverse gamma correction section 31 of FIG. 3, the standard monitor signals R, G, B are first subjected to inverse gamma conversion of the following equation, which is the inverse of the equation (6), to perform R ′, G ′. , B ′.

R ′ = 255 × (R / 255) ＾ 1 / 2.2 G ′ = 255 × (G / 255) ＾ 1 / 2.2 B ′ = 255 × (B / 255) ＾ 1/2. 2 (7) Next, R ′, G ′, B ′ obtained by the equation (7) are converted into R ″, G ″, B ″ by the matrix converter 32 as in the following equation.

[0058]

(Equation 3)

(8) The coefficient M of this matrix conversion is as follows: when the matrix of equation (5) is M1, the matrix of equation (5 ') is M2, and the color temperature correction matrix of ambient light is M3, It is a coefficient obtained by M3 × M2 × M1-1 (where M1 (-1) represents an inverse matrix of M1).

As M3, the following values are used here.

[0061]

(Equation 4)

This is based on the well-known color adaptation correction formula (VonKr
IES is well known for its color adaptation correction formula. ) Is a matrix coefficient for converting the color temperature of the monitor from 6500 K to the color temperature of ambient light 4200 K in consideration of the partial adaptation effect.

Then, the following equation is executed by the gamma correction unit 33 in FIG. 3 to obtain Rm, Gm, and Bm, which are the R, G, and B signals used for the actual monitor display.

Rm = 255 × (R ′ / 255) ＾ 1 / 1.8 Gm = 255 × (G ′ / 255) ＾ 1 / 1.8 Bm = 255 × (B ′ / 255) ＾ 1/1. 8 (9) The generation of the conversion parameters of the above-described equations (7) to (9) is based on the monitor characteristics (1 ′) to (3 ′) set in the monitor specifying device 12 and the condition (4 ′) of the ambient light. ), And the signals Rm, Gm, B obtained by equation (9).
m is sent to the monitor driver 107.

FIG. 7 is a flowchart showing the image processing according to the first embodiment of the present invention, and shows an outline of the above-described processing of this embodiment performed by the CPU 120 controlling the OS 105.

Step S11: The image on the document is read by the scanner 102 to obtain an RGB signal (scanner RGB signal).

Step S12: The scanner RGB signal is
The color space conversion unit 1 (21) converts the data into XYZ signals based on data stored in the scanner profile 22 in advance.

Step S13: The XYZ signal is converted into a standard monitor RGB signal by the color space conversion unit 2 (23) based on the data stored in advance in the standard monitor profile 24.

Step S14: The standard monitor RGB signal is converted into a color according to the characteristics of the real monitor specified by the operator using the monitor specifying device 12 and the characteristics of the surrounding ambient light specified by the ambient light specifying device 13. The space correction unit 11 corrects the monitor RGB signals for the actual monitor.

Step S15: The monitor RGB signals for the actual monitor are displayed on the monitor 108.

As described above, in the present embodiment, the XYZ signal obtained by the color space conversion unit 1 (21) of the CMS 109 is converted by the color space conversion unit 2 (23) by the expressions (5) and (6). Then, a virtual RGB signal for a standard monitor was generated.
The color space correction unit 11 performs conversion in the order of Expressions (7) to (9) to obtain Rm and G for actual monitor display.
m and Bm. Therefore, the conversion from the expressions (5) to (9) is equivalent to the conversion of the expressions (5 ′) and (6 ′) directly to the XYZ signal.

As described above, the image data is converted into the color space signal of the standard monitor in the computer 101, and the color space correction unit 11 adapts the color data to the color reproduction characteristics of the monitor actually used. There is no need to prepare color reproduction characteristic data in advance, and at that time, a correct color can be reproduced on the monitor currently actually used.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 4 is a system configuration diagram of an image processing apparatus having a CMS according to a second embodiment of the present invention.

This figure has the same basic configuration as that of FIG. 1, but further includes a monitor / ambient light measurement sensor 43. The monitor / ambient light measurement sensor 43 receives a signal from the monitor / ambient light measurement sensor 43. The color reproduction characteristic of the monitor 108 actually used is detected by the measuring device 42.

In this embodiment, a predetermined color pattern is displayed on the monitor 108, and the color pattern is displayed on the monitor 108 using a well-known R, G, B photosensor (a sensor in which color filters of R, G, B colors are arranged on the light receiving surface). ) Is measured by the monitor / ambient light measurement sensor 43 having Then, the detection signal (actually, the current value output from the three-color photosensor) is converted into a value corresponding to the color reproduction characteristics (1 ′) to (3 ′) of the monitor 108 actually used. It is converted by the light measuring device 42.

Next, the light receiving portion of the monitor / ambient light measurement sensor 43 is directed to the environmental illumination light source to measure ambient light (current values of the three color sensors), and (4 ') corresponds to the color temperature of ambient light. The monitor / ambient light measurement device 42 converts the value into a value to be calculated.

Here, a method of converting the detection signals of the R, G, and B photosensors into numerical values corresponding to the color reproduction characteristics and the color temperature of ambient light will be described.

As described below, from the detection signal measured by the monitor using the photo sensor, the following (1) chromaticity coordinates of the three-color phosphor, (2) gamma characteristic of emission luminance, and (3) color temperature of the white point And (4) obtaining a color reproduction characteristic value of the color temperature of the ambient light.

First, a conversion formula for converting the output values of the R, G, and B channels of the photosensor into X, Y, and Z is obtained in advance by the following procedure.

A light source whose X, Y, and Z values are known (= Xi, Y
i, Zi) is used to illuminate the photosensor, and the output values of the R, G, and B channels at this time are, for example, Ri, Gi, and Bi when expressed in millivolts. The relationship between the X, Y, and Z values of such a light source and the output voltage is measured for a plurality of different light sources, and the least square approximation is performed so that the following expression is satisfied with the measured values for all the light sources. Is used to find the coefficient Ajk.

Xi = A11 × Ri + A12 × Gi + A13 × Bi Yi = A21 × Ri + A22 × Gi + A23 × Bi (A) Zi = A31 × Ri + A32 × Gi + A33 × Bi Next, a red color pattern is displayed on the monitor. Red is a state in which only the red phosphor of the monitor emits light. If the monitor signal is expressed by 8 bits, (R, G, B)
= (255,0,0).

Next, a photo sensor is arranged close to the displayed color pattern, and measurement is performed with its light receiving surface facing the monitor. The measured output voltages of R, G, and B are
The values can be converted into X, Y, Z values by the formula (A), and the obtained X, Y, Z values are converted into chromaticity coordinates x, y by the following formula.

X = X / (X + Y + Z) y = Y / (X + Y + Z) (B) Similarly, the green color pattern and the blue color pattern are displayed and measured by the photo sensor, and the equations (A) and (B) are used. To obtain the chromaticity coordinates (x, y). The obtained chromaticity coordinates become the value of the color reproduction characteristic (1) of the monitor.

In the case of (3), similarly, a white color pattern is displayed on a monitor, measured by a photo sensor, and converted into x and y values. The white pattern may display (255, 255, 255) as an 8-bit monitor signal. The obtained x and y values can be set to the white color temperature of (3) using a well-known conversion table for converting chromaticity coordinate values into correlated color temperature values.

Regarding (2), a plurality of red, green, and blue patterns of different signal levels are displayed as color patterns.
It can be determined based on each sensor reading. For example, when obtaining a red gamma characteristic, (0, 0, 0), (32, 0, 0), (64,
(0,0), (96,0,0), (128,0,0),
(160,0,0), (192,0,0), (224,
Nine levels of color patterns (0, 0) and (255, 0, 0) are displayed, each color is measured by a sensor, and the Y value is obtained by equation (A). A gamma value γ such that the nine Y values thus obtained satisfy the following equation is obtained by the least squares approximation, and is set as the gamma value of (2).

Y = Ymax × (S / 255) ＾ γ (C) where Ymax represents the maximum value of the nine Y values, and S is the value of the nine monitor signals (0, 32, 64). ..., 25
5). Then, γ is determined so that the measured value Y at the signal value S corresponds to the expression (C).

As for (4), the color temperature of the white point (3)
Can be obtained by applying the same procedure to that for ambient light. That is, ambient light is measured by a photo sensor,
If the measured value is converted into an XYZ value → xy value → correlated color temperature value in the same procedure as described above, the color temperature of the ambient light becomes (4).

The data obtained by this conversion is referred to by the color space correction section 11, and Rm, Gm, and Bm for the actual monitor display are obtained as in the first embodiment.

[Third Embodiment] Next, a third embodiment of the present invention will be described with reference to FIGS. 2 above
In one embodiment, a case in which an image on a document is read from the scanner 102 and displayed on the monitor 108 is considered. In the present embodiment, image output to a printer is considered.

FIG. 5 is a system configuration diagram of an image processing apparatus including a CMS according to a third embodiment of the present invention.
This figure differs from the first embodiment in FIG. 1 in that a printer 116 is connected instead of a scanner, and a driver software 115 for controlling the printer 116 is provided in the computer 101. It is also assumed that the file 112 of the computer 101 stores image data that has been converted into virtual standard monitor RGB signals in advance. The rest is the same as in the first embodiment, and a description thereof will be omitted.

FIG. 6 is a diagram for explaining a color conversion process by CMS as a third embodiment of the present invention.

In the figure, the color space conversion unit 1 (51) converts the image data of the standard monitor RGB signal from the file 112 into
An XYZ signal is converted based on data stored in the standard monitor profile 52 in advance. In the standard monitor profile 52, a virtual standard monitor profile is stored in advance similarly to the characteristics (1) to (3) of the first embodiment. The color space conversion unit 2 (53) converts the XYZ signal from the color space conversion unit 1 (51) into a CMYK signal for a printer based on data stored in the printer profile 54 in advance, and Output to the driver software 115. In the printer profile 54, color reproduction characteristic data of the printer 116 is stored in advance.

That is, the conversion from the standard monitor RGB signal to the XYZ signal in the color space converter 1 (51) may be obtained by the inverse operation of the equations (5) and (4) described in the first embodiment. . The conversion from the XYZ signal to the CMYK signal in the color space conversion unit 2 (53) is performed by, for example, a known masking operation or storing the operation result in a printer table 54 in advance as a look-up table, and inputting the XYZ signal. There is a method of reading out a calculation result from a lookup table for a value and outputting the result.

FIG. 8 is a flowchart showing image processing according to the third embodiment of the present invention, and shows an outline of the above-described processing of this embodiment performed by the CPU 120 controlling the OS 105.

Step S21: The image data converted into the standard monitor RGB signal stored in the file 112 in advance is read.

Step S22: The standard monitor RGB signal is converted into an XYZ signal by the color space conversion unit 1 (51) based on the data stored in the standard monitor profile 52 in advance.

Step S23: The XYZ signal is converted into a CMYK signal for the printer 116 based on the data stored in the printer profile 54 in advance.

Step S24: CM for Printer 116
The print is output by the printer 116 based on the YK signal.

In the present embodiment, similarly to the first embodiment, the characteristics of the monitor 108 actually used are set from the monitor specifying device 12, and the file 1 is set in accordance with the setting.
Since the standard monitor RGB signal from the monitor 12 is corrected by the color space correction unit 11, even if the monitor to be used is changed, there is no inconvenience that the displayed color does not match the printout color.

In this embodiment, the image data converted to the standard monitor RGB signal is stored in the file 112 in advance.
The scanner 102 is connected as shown in FIG.
3 and image display software 104.
Needless to say, a system including the CMS 109 shown in FIG.

[Other Embodiments] The color processing performed in the color space conversion unit is not limited to the color processing described in the above embodiment. For example, the coefficient M according to the color vision characteristic of the user may be created by performing a fine adjustment based on the instruction of the user with respect to the coefficient M of the first embodiment.

That is, the color conversion section can perform color processing different from the color processing performed based on the output device profile (standard monitor profile) by the CMS. Therefore, it is easy to design a color matching process according to the situation of the output device, and it is possible to provide more accurate color matching. That is, it is possible to use the CMS supported by the OS and realize more accurate color matching.

In the above-described embodiment, the monitor 10
8 has been described as a CRT. However, in a liquid crystal display, a color plasma display, or the like, the coloring characteristics can be defined in the same manner as (1 ′) to (3 ′). The parameters of the expression may be set.

In each of the above-described embodiments, a pre-defined standard monitor is assumed, and a predetermined relationship is established so that when the color of the image on the document is reproduced on the standard monitor, correct color reproduction is realized. Although the description has been made using a color space defined in advance, for example, XYZ, L * a * b, L * u
Other color spaces may be used as long as they are colorimetrically defined color space signals such as * v *.

The present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a scanner, a printer, etc.) as in the present embodiment, but it can be applied to an apparatus (one device). For example, a device such as a copier, a facsimile machine, or the like, which simply displays data read by scanning a document image or image data stored in a storage device on a monitor, or a device displayed on a monitor. It goes without saying that the present invention can be similarly applied to an apparatus that simply prints out image data.

Further, an object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, magnetic tape, non-volatile memory card, ROM, etc. can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) And the like perform part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the program code is read based on the instruction of the program code. It goes without saying that a CPU or the like provided in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the above-described flowcharts. However, in brief, at least in the first embodiment, 9 and the third embodiment, the program code of each module shown in the example of the memory map in FIG. 10 may be stored in the storage medium.

FIG. 9 is a diagram showing an example of a memory map according to the first embodiment of the present invention. In the figure, an “image reading program” reads an image on a document by controlling the scanner 102 and outputs an RGB signal (scanner RG).
B signal).

"Color space conversion program 1": scanner R
The color space conversion unit 1 (21) converts the GB signal into XYZ data based on data stored in the scanner profile 22 in advance.
Convert to a signal.

"Color space conversion program 2": The XYZ signal is converted by the color space conversion unit 2 (23) into the standard monitor R based on the data stored in the standard monitor profile 24 in advance.
Convert to a GB signal.

"Color space correction program": standard monitor R
The color space correction unit 11 corrects the GB signal into a monitor RGB signal for a real monitor in accordance with the characteristics of the real monitor specified by the monitor specifying device 12 by the operator.

"Monitor output program": A monitor RGB signal for an actual monitor is displayed on the monitor 108.

FIG. 10 is a diagram showing an example of a memory map according to the third embodiment of the present invention. In the figure, “image data reading program”: reads image data converted into standard monitor RGB signals stored in the file 112 in advance.

"Color space conversion program 11": monitor R
The color space conversion unit 1 (51) converts the GB signal into XY based on data stored in the standard monitor profile 52 in advance.
Convert to Z signal.

"Color space conversion program 12": Converts XYZ signals into CMYK signals for printer 116 based on data stored in printer profile 54 in advance.

"Printer output program": Printer 1
The print is output by the printer 116 based on the CMYK signal for 16.

[0122]

As described above, it is possible to provide an image processing apparatus and an image processing method capable of performing stable color reproduction between devices having different color reproduction characteristics even under different ambient light sources.

[0123]

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an image processing apparatus including a CMS according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a color conversion process by a CMS according to the first embodiment of the present invention.

FIG. FIG. 3 is a diagram illustrating color conversion in a color space correction unit 11 according to the first embodiment of the present invention.

FIG. 4 is a system configuration diagram of an image processing apparatus including a CMS according to a second embodiment of the present invention.

FIG. 5 is a system configuration diagram of an image processing apparatus including a CMS according to a third embodiment of the present invention.

FIG. 6 is a diagram illustrating a color conversion process by a CMS according to a third embodiment of the present invention.

FIG. 7 is a flowchart illustrating image processing according to the first embodiment of the present invention.

FIG. 8 is a flowchart illustrating image processing according to a third embodiment of the present invention.

FIG. 9 is a diagram illustrating an example of a memory map according to the first embodiment of the present invention.

FIG. 10 is a diagram illustrating an example of a memory map according to the first embodiment of the present invention.

FIG. 11 is a diagram illustrating an example of a system configuration of an image processing apparatus including a CMS as a conventional example.

Claims (20)

[Claims] 1. An image processing apparatus for converting a color space of input image data and outputting the converted color space, wherein an image signal input from an input device is converted based on color space characteristic information of the input device stored in advance. A first color space conversion unit that converts the image signal into a device-independent color space image signal; and an image signal output from the first color space conversion unit.
A second color space conversion unit configured to convert the color space characteristic information of the standard output device into an image signal of a color space dependent on the standard output device based on the color space characteristic information stored in advance; 1 specifying means, 2nd specifying means for specifying the color characteristics of ambient environmental light, and image signals output from the second color space converting means.
An image processing apparatus comprising: a correction unit configured to perform correction in accordance with the color reproduction characteristics specified by the first and second specification units. 2. An image signal input from the input device is an RGB signal, an image signal in a color space independent of the device is an XYZ signal, and an image signal in a color space dependent on the standard output device is the standard output device. RG
2. The image processing apparatus according to claim 1, wherein the signal is a B signal. 3. The image processing apparatus according to claim 1, wherein the correcting unit performs inverse gamma correction, matrix conversion, and gamma correction on the image signal in the color space depending on the standard output device, thereby converting the image signal in the color space depending on the output device. The image processing apparatus according to claim 2, wherein the correction is performed. 4. The image processing apparatus according to claim 1, further comprising a supply unit that supplies a color space signal from the correction unit to the output device. 5. The apparatus according to claim 1, wherein the output device is a display, and the supply unit converts the color space signal from the correction unit into an analog signal and supplies the analog signal to the display as a raster signal. 5. The image processing device according to 4. 6. The first designating means includes first measuring means for measuring a color reproduction characteristic of the output device, and the color reproduction of the output device is based on a measurement value from the first measuring means. The image processing apparatus according to claim 1, wherein the characteristic is generated. 7. The second designation unit includes a second measurement unit that measures ambient light, and generates a color reproduction characteristic of the output device based on a measurement value from the second measurement unit. The image processing apparatus according to claim 1, wherein: 8. The color separation characteristics of the standard output device are as follows:
2. The image processing apparatus according to claim 1, wherein the chromaticity coordinates of the three-color phosphor, the gamma characteristic of the emission luminance, and the color temperature of the white point. 9. A method of converting an image signal in a color space dependent on the standard output device into an image signal in a color space independent of the device based on the previously stored color separation characteristics of the standard output device. Color space conversion means, and the image signal output from the third color space conversion means,
A fourth color space conversion unit configured to convert the image signal into a color space image signal dependent on the second output device based on the color space characteristic information of the second output device stored in advance; The image signal output from the conversion means is
Second supply means for supplying to the second output device;
The image processing apparatus according to any one of claims 1 to 3, further comprising: 10. The second output device is a printer, wherein the fourth color space conversion means converts an image signal output from the third color space conversion means into a CMYK signal. The image processing device according to claim 9, wherein: 11. The image processing apparatus according to claim 9, wherein the third color space conversion means is an inverse conversion of the conversion performed by the second color space conversion means. 12. An image processing method for converting and outputting a color space of input image data, wherein an image signal input from an input device is dependent on the device based on characteristic information of the color space of the input device. A first color space conversion step of converting the image signal selected in the first color space conversion step into an image signal of a color space not to be converted, based on the color space characteristic information of the standard output device. To convert to an image signal in a color space dependent on
A color space conversion step, and a correction step of correcting the image signal obtained in the second color space conversion step according to the color reproduction characteristics of an output device and / or the color characteristics of ambient environmental light. Image processing method. 13. An image signal input from the input device is an RGB signal, an image signal in a color space independent of the device is an XYZ signal, and an image signal in a color space dependent on the standard output device is the standard output device. R
13. The image processing method according to claim 12, wherein the signal is a GB signal. 14. In the correcting step, an image signal in a color space dependent on the standard output device is subjected to inverse gamma correction,
14. The image processing method according to claim 13, wherein matrix conversion and gamma correction are performed to correct an image signal in a color space dependent on the output device. 15. A color separation characteristic of the standard output device, a chromaticity coordinate of a three-color phosphor, a gamma characteristic of emission luminance,
13. The image processing method according to claim 12, wherein a color temperature of a white point is used. 16. A computer readable memory containing a program code for image processing for converting a color space of input image data, wherein an image signal input from an input device is converted based on color space characteristic information of the input device. A code of a first color space conversion step for converting into an image signal of a device-independent color space, and an image signal selected in the first color space conversion step are converted into color space characteristic information of a standard output device. A second color space based on the standard output device.
And a code of a correction step of correcting the image signal obtained in the second color space conversion step in accordance with the color reproduction characteristics of the output device and / or the color characteristics of ambient environmental light. A computer readable memory comprising: 17. A color processing method for performing a color matching process according to an output device, comprising the steps of: executing, via an operating system, color data subjected to a color matching process according to a source profile and a standard profile corresponding to a source device; And inputting information on the color characteristics of the output device, performing a reverse process of the process based on the standard output profile on the color data subjected to the color matching process, and performing a color process according to the monitor characteristics. A color processing method comprising: 18. The apparatus according to claim 17, wherein the output device is a monitor, and the information on the color characteristics of the output device is information on chromaticity coordinates and gamma characteristics of the phosphor and color temperature of a white point. The color processing method described. 19. The color processing method according to claim 18, wherein the information on the color characteristics of the output device is based on a manual instruction from a user. 20. The color processing method according to claim 17, further comprising the step of inputting information relating to ambient light when observing an output image, and performing color processing according to said ambient light.