JP3416352B2 - Image processing apparatus and method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and a method therefor, for example, an image processing apparatus to which color processing for matching an object color due to reflected light of a printed matter and a light source color such as a display color of a light emitter is applied. And its method.

[0002]

2. Description of the Related Art With the recent technical improvement in image processing apparatuses, apparatuses having a color image processing function have been provided at low cost. Along with this, CG (Computer Grap
Color images can now be handled easily not only in special fields such as design creation using hics) but also in general offices.

In such a situation, when a color image created on a monitor such as a CRT is output on a recording medium by a printer or the like, the operator can see the colors of these two images (display image and print image). There was a problem that they looked different. Therefore, in order to solve this problem, a color management system is drawing attention.

The color management system is a system for expressing a color image by using a common color space in a plurality of devices, thereby avoiding that the color of the image looks different for each device. This means that all the colors in an image are represented in one color space based on the basic concept that two colors represented by the same coordinate value in a certain color space look the same to the human eye. , I try to match the appearance of the color of the image in each device. In the current color management system, there is proposed a method of correcting the difference in color appearance between devices by using XYZ tristimulus values as the color space.

An environment for observing a conventional image will be described with reference to FIG. FIG. 10 shows the monitor 20.
3 shows the case where the same image 202 as the printed matter 201 is displayed on the screen 3. Reference numeral 204 denotes ambient light when observing an image, for example, light emission of a fluorescent lamp. Reference numeral 205 denotes a vertical bracket, which is installed to prevent the light emission of the monitor 203 from affecting the observation of the printed matter 201. Under such an environment, color measurement (measurement of chromaticity coordinates) is performed on each of the printed matter 201 and the image 202 on the monitor 203. It is the most ideal result in the color management system that the colorimetric values of the two match.

[0006]

However, as shown in FIG.
Under the observation environment as shown in (1), the ambient light 204 can change variously depending on the situation, and therefore the printed matter 201 and the image 202 on the monitor 203 are not always observed under a constant environment. Therefore, even if an equal color on a color space is obtained by color management under a certain ambient light 204, if the ambient light 204 is changed, images that have been viewed as the same color until now will be completely different colors. Will look like.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an image processing apparatus and method capable of performing optimum color management in any viewing environment.

[0008]

As one means for achieving the above object, the image processing apparatus of the present invention has the following configuration.

In order that the color of the input image and the color of the display image match,
An image processing device that performs conversion processing according to ambient light,
Refer to the holding means for holding the adaptation ratio corresponding to a plurality of combinations of white information and ambient light information of the display device, the input means for inputting the white information and ambient light information of the display device, and the holding means. Deciding means for deciding an adaptation ratio corresponding to the input white information of the display device and ambient light information,
Calculating means for calculating a reference white value from the white information of the display device and the ambient light information based on the determined adaptation ratio, and converting the image signal indicating the input image based on the calculated reference white value And a converting means for

Further, it is characterized in that it further comprises detection means for detecting ambient light information.

For example, the white color information of the display device is obtained from the profile of the display device, and the image signal converted by the converting means is referred to the profile of the display device to obtain a color depending on the display device. It is characterized by further comprising color conversion means for converting into a signal.

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

As one method for achieving the above-mentioned object, the image processing method of the present invention comprises the following steps.

That is, there is provided an image processing method for performing conversion processing according to ambient light so that the input image and the display image have the same tint, and an input step of inputting white information of the display device and ambient light information, The accommodating ratio corresponding to the input white information and ambient light information of the display device is determined with reference to the holding unit that holds the accommodating ratio corresponding to a plurality of combinations of white information and ambient light information of the display device. Determining step, based on the determined adaptation ratio, a calculating step of calculating a reference white value from the white information of the display device and the ambient light information, and the input image based on the calculated reference white value. And a conversion step of converting the image signal shown.

Further, it is characterized by further comprising a detection step of detecting ambient light information.

For example, the white color information of the display device is obtained from the profile of the display device, and the image signal converted in the converting step is referred to the profile of the display device to determine the color depending on the display device. It is characterized by further including a color conversion step of converting into a signal.

For example, the conversion using the calculated reference white value is characterized by using a conversion formula according to the von Klees formula.

[0024]

[0025]

[0026]

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings.

<First Embodiment> FIG. 1 shows an observation environment in this embodiment. In FIG. 1, the same numbers are given to the same configurations as those of FIG. 10 shown in the above-mentioned conventional example,
The description is omitted. In FIG. 1, reference numeral 206 denotes an ambient light sensor, which is installed on the monitor 203 or a printer (not shown) and configured to detect the ambient light 204. Hereinafter, the case of observing the printed matter 201 and the display image 202 on the monitor 203 will be described. The monitor 203 in the present embodiment is not limited to the CRT display, and includes a liquid crystal display and the like.

Under the environment shown in FIG. 1, the print image 20 is printed.
In order for the operator to see 1 and the display image 202 as the same color, first, the following method can be considered.

Ambient light sensor 206 provides information about ambient light 204.
Then, based on the ambient light information, what chromaticity value (for example, XYZ) each color forming the image is represented in the output destination device is predicted. Then, the predicted chromaticity value is reproduced as faithfully as possible with reference to the characteristic profile of each device, so that the color matching can be obtained. This ambient light value means the ambient light sensor 206
The chromaticity value of the light source itself or the chromaticity value obtained when the paper is measured under the ambient light may be used.

A configuration for realizing such processing is shown in FIG. 2 and will be described below.

In FIG. 2, 101 is a scanner equipped with a CCD sensor and the like, 102 is a scanner color converter for converting RGB values read by the scanner 101 into XYZ values, and 103 is a color conversion characteristic in the scanner color converter 102. This is the scanner profile to hold. A color signal conversion unit 104 corrects the XYZ values to values optimal for the current observation environment according to the ambient light information 108 read by the sensor 109. Also, 105 is the XYZ value CR
A monitor color conversion unit for converting the RGB values to be displayed on the monitor 107 such as T, and 106 is a monitor profile that holds the color conversion characteristics in the monitor color conversion unit 105.

First, the scanner 101 reads an input image (printed material 201), and the scanner color conversion unit 102 refers to the scanner profile 103 in which the scanner characteristic data is stored in advance, and then the R1G1B1 value obtained from the scanner 101 is calculated as follows. It is converted to X1Y1Z1 value which is a device-independent color signal. Then, the color signal conversion unit 1
In 04, the color signal value X1Y1Z is calculated based on the ambient light information 108 obtained from the sensor 109 for sensing the ambient light.
The color indicated by 1 is converted into a signal value X2Y2Z2 that would be obtained when colorimetry is performed under the environment of the ambient light. Then, the monitor color conversion unit 105 refers to the monitor profile 106 in which the monitor characteristic data is stored in advance, and calculates R2G2B2 which is the input value to the monitor 107 corresponding to the X2Y2Z2 value.

By performing color management in the configuration as described above, the read image signal is represented by X2Y2Z2 according to the current ambient light information 108 in the XYZ color space.

By performing color conversion in consideration of ambient light in this way, more appropriate color management should be realized.

However, in the above-mentioned example, the colors of the print image 201 and the display image 202 recognized by the operator are
In the print image 201, it is the reflected light color (object color) on the recording medium, and in the display image 202, it is the light emission color (light source color) of the light source. That is, since the color development modes are different between the two, even if the colors are expressed by the same value in the same color space, they are often not recognized as the same color by the operator.

Therefore, for the purpose of enabling human beings to perceive the same color when visually observed, even in images having different coloring modes, the following values are set as follows. Various color management methods are possible.

When a person observes a color, it is considered that a certain white color is used as a reference and all colors are recognized by comparison with the white color. Here, consider the case where a monitor display image and a print image placed under a certain ambient light are observed. Then, under the environment, there are many criteria such as white on a monitor, white of ambient light, and white of a printed image illuminated by ambient light (white background of paper) that can be a reference when a person recognizes a color. White color is present. It can be said that human beings observe the color with reference to the white color adapted to the plurality of white colors at a predetermined ratio.

Therefore, it is more appropriate to calculate a white color (hereinafter, referred to as a reference white color) which is a reference when a human observes a color, and convert all the colors forming an image based on the reference white color. Color management is possible.

As a more specific method, when calculating the reference white, first, one adaptation ratio between the white on the monitor under the fluorescent lamp of the reference white and the white of the ambient light is determined in advance. . Then, a more appropriate color management is realized by calculating the reference white color using the adaptation ratio and performing color conversion based on the reference white color.

However, in such color management, when calculating the reference white, the adaptation ratio is fixed regardless of the observation environment. As the ambient light when an image is actually observed, not only fluorescent lights but also various lights are present. Since the adaptation ratio of the reference white to each white differs depending on the different ambient light, if the adaptation ratio is fixed to one, it is desirable to calculate the optimum reference white for all observation environments. Absent. Further, even when the light other than the fluorescent light is mixed in the ambient light, the optimum reference white cannot be calculated.

Therefore, in the present embodiment, by calculating the optimum reference white color in all observation environments,
It is characterized by enabling optimal color management.

FIG. 3 shows a block diagram of the image processing apparatus in this embodiment. In FIG. 3, 10 is a scanner for optically reading image data on a recording medium by an image pickup device such as a CCD and inputting the image data, and 11 is an image processing unit for performing various image processing including color conversion processing which is a feature of this embodiment. 1
Reference numeral 2 denotes a monitor such as a CRT that displays image data. Further, 13 is a communication unit that sends and receives image data via a general communication line, 14 is a printer that prints out image data on a recording medium, and 15 is a command input by an operator such as an operation panel or an image is sent to the operator. It is an operation unit that notifies the state of the processing device. Reference numeral 16 denotes an ambient light sensor, which detects ambient light under the current environment, as described later.

In this embodiment, the image processing is performed so that the color of the original image read by the scanner 10 and the color when the image is displayed on the monitor 12 can be recognized as the same color under any environment. It is characterized in that an appropriate color conversion process is performed in the section 11.

The block diagram of FIG. 4 shows an extracted configuration for performing the color conversion processing, which is a feature of this embodiment. Figure 4
Performs color conversion on the image data read by the scanner 10 in the image processing unit 11, and the monitor 12
The structure for displaying is shown. In FIG. 4, 302 is a scanner color conversion unit, 303 is a scanner profile, and 3 is a scanner profile.
Reference numeral 04 is a color signal conversion unit, 305 is a monitor color conversion unit, and 306.
Is a monitor profile. Reference numeral 310 denotes a CPU, which comprehensively controls each configuration of the image processing unit 11 according to a control program stored in the ROM 311 and including, for example, processing shown in a flowchart described later. Three
A RAM 12 operates as a work area of the CPU 310. It should be noted that the detailed configuration of the image processing unit 11 shown in FIG. 4 shows only the part related to the color conversion process, and the configuration related to other image processes is omitted. In addition, a configuration that is indispensable in normal image processing, such as an A / D conversion unit that converts an analog image signal input from the scanner 10 into a digital signal, will be omitted.

The color management process in this embodiment will be described below with reference to the configuration shown in FIG. 4 and the flow chart in FIG.

In FIG. 5, first, in S101, the image output on the recording medium is read as an original by the scanner 10 to obtain an R1G1B1 image signal. Here, the color of the document image is a so-called object color recognized as reflected light.

Next, in step S102, the image processing unit 1
In FIG. 1, the R1G1B1 data obtained by the scanner 10 depending on the scanner 10 is input to the scanner color conversion unit 302 in the image processing unit 11 and refers to the information of the scanner profile 303 to refer to the device-independent XYZ.
Converted to the value X1Y1Z1 in the color space.

Here, the scanner profile 303 stores in advance information about color characteristics and the like in the scanner 10. For example, a color conversion matrix for converting scanner-dependent RGB values into device-independent XYZ values, and the like. , A lookup table (LUT), etc. are stored. Then, in step S103, the ambient light information 309 from the ambient light sensor 16 is input. Then, in step S104, the X1Y1Z1 signal converted in step S102 in the color signal conversion unit 304 is
Ambient light information 309 obtained from the ambient light sensor 16 and monitor white information 3 obtained from the monitor profile 306.
08, it is converted into an X2Y2Z2 signal that takes into account the correction of the coloring mode in the ambient light and the object color / light source color. The details of the color signal conversion process in step S104 (the conversion process in the color signal conversion unit 304) will be described later.

Next, in step S105, the X2Y2Z2 signal converted in step S104 is input to the monitor color conversion unit 305 and converted into an R2G2B2 value depending on the monitor 12 with reference to the information of the monitor profile 306.

Here, in the monitor profile 306,
Information about the color characteristics of the monitor 12 is stored in advance. For example, in addition to the monitor white information, the monitor white information such as the color temperature of the monitor 12, the emission brightness, and the chromaticity value of the phosphor,
Color conversion characteristic information from a signal in the standard color space to a device-dependent color space signal is stored.

Finally, in step S106,
The document image read by the scanner 10 in step S101 is displayed on the monitor 12.

Next, the color signal conversion processing (conversion processing in the color signal conversion unit 304) in step S104 described above will be described in detail.

First, referring to FIG. 6, the color signal conversion unit 304
The outline of the conversion process in step S1 will be described. FIG. 6 is a diagram showing a method of calculating a position in a predetermined color space of a reference white, which is a reference for human color perception in the current environment.

When observing an image displayed on the monitor 12 as in the present embodiment, a person does not fully adapt to only the white color on the monitor 12 and recognizes all the colors. It is thought to be accommodating both to ambient light and to some extent. Therefore, as shown in FIG. 6A, the reference white point, which is the reference for viewing the color, is the monitor 1
The predetermined adaptation ratio (s: 1-
s).

Here, a detailed block configuration of the color signal conversion unit 402 is shown in FIG. 7 and will be described.

In FIG. 7, 401 is an adaptation ratio storage unit that holds a plurality of adaptation ratios in advance, 402 is an adaptation ratio determination unit that determines an appropriate adaptation ratio, 403 is a reference white calculation unit,
A signal conversion unit 404 converts an actual color signal. The adaptation ratio determination unit 402 and the reference white calculation unit 403 include ambient light information 309 detected by the ambient light sensor 16,
And the monitor white information 308 held in the monitor profile 306 is input.

The processing in the color signal conversion unit 304 shown in FIG. 7 will be described in detail below with reference to the flowchart in FIG.

First, step S10 shown in FIG. 5 described above.
3, ambient light information 309 is obtained from the ambient light sensor 16 as information on light (ambient light) obtained by a light source around the sensor 16. Ambient light information 309
The present operating environment of the image processing apparatus of the present embodiment is shown.
The ambient light information 309 may be spectral data or color signals in an XYZ color space, an RGB color space, or the like. Further, in the image processing apparatus, the ambient light sensor 16 may not be directly connected, and the operator may manually input a color signal or the like corresponding to the ambient light information 309 from the operation unit 15. Further, this ambient light information 309 corresponds to the reference light source L in FIG. At this time, monitor white information 308 such as the temperature of the monitor white for displaying the image, the emission brightness, and the chromaticity value is already obtained from the monitor profile 306. This monitor white information 308 corresponds to the monitor white point M in FIG.

Here, the adaptation ratio storage unit 401 calculates the corresponding adaptation ratio when the ambient light is assumed to come from a predetermined reference light source, for each of the plurality of reference light sources, for example, LUT or the like for each monitor white point. It is held in advance in the form of. As the reference light source in this embodiment,
For example, light sources A, C, D9 defined by JIS standard
3, D65, D50, F, etc. are used.

In step S201 of FIG. 8, the adaptation ratio determination unit 402 refers to the ambient light information 309 and determines whether the ambient light is a single reference light source by any of the reference light sources described above. Here, if it is determined that the ambient light is the single reference light source, the process proceeds to step S202.

In step S202, the adaptation ratio determining unit 402 determines the ambient light information 309 and the monitor white information 30.
8, the corresponding adaptation ratio is selected from the adaptation ratio storage unit 401. The selected adaptation ratio is then input to the reference white color calculation unit 403, and in step S203, the same ambient light information 3 as that input to the adaptation ratio determination unit 402.
09 and the monitor white information 308, the reference white information suitable for the current observation environment is calculated.

The method of calculating the reference white information in the reference white calculator 403 will be specifically described below.

For example, assuming that the reference white point (perceptual reference white point) W adapts to the monitor white point M on the XYZ color space coordinates is s, the ratio adapting to the reference light source point L is shown in FIG. It is represented by 1-s as shown in a). Also,
The tristimulus values and chromaticity values of the reference light source point L corresponding to the ambient light information 309 are Xw1, Yw1, Zw1, xw1, and yw1, respectively, and the monitor white point M corresponding to the monitor white information 308 is also Xw2. , Yw2, Zw2, xw2, yw2. Then, the tristimulus values Xw, Yw, Z of the reference white signal
The w and the chromaticity values xw and yw are obtained by the following (Equation 1) and (Equation 2).

Tristimulus value Xw = (1-s) * Xw1 + s * Xw2 Yw = (1-s) * Yw1 + s * Yw2 Zw = (1-s) * Zw1 + s * Zw2 ... ( Expression 1) -Chromaticity value xw = (1-s) * xw1 + s * xw2 yw = (1-s) * yw1 + s * yw2 ... (Expression 2) where ambient light at the time of image observation ( Since the adaptation ratio of the reference white point W to the monitor white point M and the reference light source L differs depending on the reference light source), that is, the value of the adaptation ratio s in the above (Equation 1) and (Equation 2) depends on the ambient light. Accordingly, the reference white point M also changes according to the ambient light (reference light source).

For example, the color temperature of the monitor 12 is 6500K.
When the reference light source corresponding to the ambient light is the D65 light source (correlated color temperature 6504K), there is almost no difference between the ambient light and the white color of the monitor, and therefore the three points ((a) in FIG. M, W, L) are represented as almost one point.

The color temperature of the monitor 12 is 6500K.
Then, when the ambient light is the F light source of the fluorescent lamp, the person adapts to both the monitor white color and the ambient light at a certain ratio. The adaptation ratio is about 50% to 40% for the monitor white point M, and about 50% to 60% for the ambient light (reference light source point F). This state is shown in FIG. In FIG. 6B, W
(F) is a reference white point under the F light source.

The color temperature of the monitor 12 is 6500K.
Then, when the ambient light is the A light source, as in the case of the fluorescent lamp, a person adapts to both the monitor white color and the ambient light.
The adaptation ratio is considerably inclined to the ambient light side, and is 20% to 10% for the monitor white point M and about 80% to 90% for the ambient light (reference light source L). This state is shown in FIG. In FIG. 6C, W (A) is the reference white point under the A light source.

Therefore, in this embodiment, the optimum reference white point can be calculated by determining the optimum adaptation ratio according to the ambient light.

The method of calculating the reference white point when the ambient light is one of the reference light sources has been described above. Next, a case will be described in which it is determined in step S201 that the ambient light is not a single reference light source but a mixture of a plurality of reference light sources.

In this case, the process proceeds to step S204, and the adaptation ratio determining unit 402 determines the ambient light information 309.
Based on the above, it is determined what kind of reference light source the current ambient light has and what kind of mixing ratio it has.

Then, in step S205, the adaptation ratio is calculated. In this case, since the adaptation ratio in the case where the ambient light is the reference light source is stored in the adaptation ratio storage unit 401 in advance, it is a mixture of arbitrary reference light sources. The adaptation ratio in ambient light can be calculated as a mixture of the adaptation ratios of these reference light sources.

Referring now to FIG. 9, step S205
The method of calculating the adaptation ratio with respect to the ambient light in which the reference light source is mixed will be specifically described.

FIG. 9 shows a case where the ambient light S obtained as the ambient light information 309 is a mixture of the reference light source A and the reference light source B, and the mixture ratio is a: b. Here, in the adaptation ratio storage unit 401, when an image is observed with the reference light source A as ambient light, the adaptation ratio corresponding to the monitor white information 308 is a1 on the monitor white point M side (1-a1 on the ambient light A side). ), And similarly, the adaptation ratio corresponding to the monitor white information 308 when an image is observed using the reference light source B as ambient light is b1 on the monitor white point M side.
It is assumed that it is stored as a ratio of (1-b1 on the ambient light B side).

When the adaptation ratio determining unit 402 determines that the ambient light S is a mixture of the reference light sources A and B, the reference light source A
And the adaptation ratio a1 corresponding to the monitor white information 308 of B
And b1 are extracted from the adaptation ratio storage unit 401, and the ambient light S
It outputs to the reference white calculation unit 403 together with the information of the mixing ratio a: b of the reference light sources A and B in.

Next, the process proceeds to step S206 to calculate the reference white color. Through the processing up to this point, the coordinate values of the monitor white point M, the ambient light S, and the reference light sources A and B are known on the XYZ color space coordinates as shown in FIG. In the reference white calculation unit 403, first, the reference white points Wa and Wb with respect to the monitor white points M of the reference light sources A and B are calculated.
To calculate. Since the mixing ratio of the reference light sources A and B in the ambient light S is a: b, the reference white point W under the ambient light S is the reference white point Wa under the reference light source A and the reference white point under the reference light source B. It is calculated as a mixture of a: b of the white point Wb. This calculation formula is shown in (Formula 3).

Wa = (1-a1) .A + a1.MWb = (1-b1) .B + b1.MW = a.Wa + b.Wb (Equation 3) Reference white calculation unit 403 In, the reference white point W of the ambient light S is calculated according to the above-described (Equation 3).
The reference white point W can be calculated in the same manner by the method described below.

Of course, the method of calculating the reference white point W in the reference white calculation unit 403 is not limited to the above-mentioned example, and for example, the corresponding adaptation ratio is estimated for ambient light composed of expected mixture of predetermined reference light sources. Calculated in advance, LU
It may be stored in the adaptation ratio storage unit 401 in a format such as T. In this case, the adaptation ratio determination unit 402
Based on the ambient light information 309, one adaptation ratio corresponding to closer ambient light is extracted, and thereafter, the reference white point may be calculated in accordance with the adaptation ratio. Therefore, the accuracy is low, but the amount of calculation is small, The processing speed is also improved.

As described above, step S203
Alternatively, in step S206, the reference white point corresponding to the ambient light is obtained.

Next, the process proceeds to step S207, and the signal conversion unit 404 performs color conversion of the entire image based on the reference white point signal calculated by the reference white calculation unit 403.

The image displayed on the monitor 12 is observed on the basis of the reference white color calculated as described above, while the printed matter such as the original image read by the scanner 10 is the background of the recording medium (paper). And the white of ambient light.

Here, in the XYZ color space, if the reference white points are Xw, Yw, Zw and the ambient light is Xs, Ys, Zs,
Image signals X1, Y1, read by the scanner 10,
Z1 can be converted into image signals X2, Y2, Z2 to be displayed on the monitor 12 by using (Equation 5) which is a modification of the von Kreis equation shown below.

[0083]

[Equation 1]

The signal conversion section 404 can also perform conversion including image contrast conversion in consideration of human visual characteristics, that is, conversion in consideration of gamma characteristics. The conversion formula is shown in (Formula 6) below.

[0085]

[Equation 2]

As described above, the color signal conversion unit 30
In 4, the input image signal X1Y1Z1 is converted into the image signal X2Y2Z2 corresponding to the current observation environment.

As described above, the image signal X2Y2Z2 obtained by the color signal conversion processing shown in the flowchart of FIG.
In the monitor color conversion unit 305, the monitor profile 3
The image is converted into an R2G2B2 signal which is a monitor input signal with reference to 06, and an image subjected to color management is displayed on the monitor 12 based on the R2G2B2 signal.

When the color temperature indicated by the ambient light information 309 (ambient light S) is lower than 5000 K in the adaptation ratio determination unit 402, the ratio of adaptation to the ambient light S side in the actual adaptation ratio at 5000 K. It is desirable to set an adaptation ratio that is higher. This is because it is empirically known that this makes it easier to visually recognize.

In the present embodiment, the XYZ color space has been described as a common color space, but this is not limited to the XYZ color space, and L * a * can be used as long as it is a color space that can absorb differences in devices. Any color space such as b * color space or L * u * v * color space may be used.

Further, although the ambient light sensor 16 is described as an independent structure for the sake of simplicity of description, for example, the monitor 12 is used.
It may be included in another configuration as long as the observation environment can be measured, such as the front surface or the upper surface of the printer 14.

Further, in the present embodiment, an example in which the adaptation ratio is determined according to the ambient light information 309 and the monitor white information 308 has been described. For example, the ambient light information 309.
Of course, it is also possible to make a decision according to only the monitor white information or only the monitor white information.

As described above, according to this embodiment, the perceptual reference white color in the image displayed on the monitor is calculated based on the current ambient light information, and the input image signal is converted based on the perceptual reference white color. As a result, the operator can observe the same color as the color of the document image (object color) that is a printed matter and the color of the display image on the monitor (light source color).
That is, it is possible to realize an appropriate color management process according to the viewing environment.

In the present embodiment, an example of setting the adaptation ratio for two whites, that is, the monitor white and the ambient white, in order to calculate the reference white has been described. Even if the adaptation ratio for white is set, the same effect can be obtained with the same idea as the present invention.

Further, in the present embodiment, an example has been described in which the adaptation ratio is set from two white colors, the monitor white color and the ambient light white. However, the adaptation ratio is not limited to these two factors, but the monitor color temperature, background Similar effects can be obtained by setting the adaptation ratio according to the visual environment such as color, adaptation time, and monitor surface reflection amount.

The color conversion method described in this embodiment has a function of displaying an image to be printed out on a recording medium on a monitor in advance so that the operator can confirm the so-called previewer function. The present invention can be applied to a copier, a printer, etc. with an attached.

Furthermore, the above-described color conversion method can be applied to any image processing apparatus as long as it is an apparatus that performs color signal conversion between different devices in order to realize a color management system.

Further, the present invention may be applied to a system composed of a plurality of devices such as a host computer, an interface and a printer, or to an apparatus composed of a single device such as a copying machine. Further, it goes without saying that the present invention can be applied to the case where it is implemented by supplying a program to a system or an apparatus. In this case, the storage medium storing the program according to the present invention constitutes the present invention. Then, by reading the program from the storage medium to the system or device, the system or device operates in a predetermined manner.

[0098]

As described above, according to the present invention, the human perceptual reference white is calculated according to the ambient light which is the observation environment, and the color conversion of the entire image is performed according to the reference white signal. , It is possible to perform correction so that the object color and the light source color appear to match. Therefore, it is possible to realize an appropriate color management process according to the viewing environment.

[0099]

[Brief description of drawings]

FIG. 1 is a diagram showing an image observation environment in an embodiment according to the present invention.

FIG. 2 is a diagram illustrating a color conversion processing method according to the present embodiment.

FIG. 3 is a block diagram showing a configuration of an image processing apparatus of this embodiment.

FIG. 4 is a block diagram showing a configuration of an image processing unit in the present embodiment.

FIG. 5 is a flowchart showing a color management processing procedure in the present embodiment.

FIG. 6 is a diagram for explaining a method of calculating a reference white when ambient light is a reference light source.

FIG. 7 is a block diagram showing a detailed configuration of a color signal conversion unit in this embodiment.

FIG. 8 is a flowchart showing a color signal conversion processing procedure in the present embodiment.

FIG. 9 is a diagram for explaining a method of calculating a reference white color when ambient light is a color mixture of a reference light source.

FIG. 10 is a diagram showing a conventional image observation environment.

[Explanation of symbols]

10 scanner 11 Image processing unit 12 monitors 16 Ambient light sensor 302 Scanner color converter 303 Scanner profile 304 color signal converter 305 Monitor color converter 306 Monitor profile 401 Adaptation ratio storage unit 402 Adaptation ratio determination unit 403 Standard white color calculator 404 signal converter

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-9-93451 (JP, A) JP-A-8-98204 (JP, A) JP-A-9-35050 (JP, A) JP-A-6- 213726 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 1/40-1/409 H04N 1/46 H04N 1/60

Claims (7)

(57) [Claims] 1. A color tone of an input image and a display image match each other.
Is an image processing device that performs conversion processing according to ambient light.
Te, a plurality of combinations of white information and the ambient light information display device
Holding means for holding the adaptation ratio corresponding to the input device, and input means for inputting white information and ambient light information of the display device
And referring to the holding means, the input display device white
Determining means for determining the adaptation ratio corresponding to the color information and the ambient light information, and the white information of the display device based on the determined adaptation ratio.
A calculating means for calculating a reference white value from broadcast and the ambient light information, the input image based on the calculated reference white value shown
The image processing apparatus characterized by having conversion means for converting to image signal. 2. Further, a detecting means for detecting ambient light information is provided.
The image processing apparatus according to claim 1, characterized in that it has. 3. The white information of the display device is the display device.
Obtained from the Oki profile, The image signal converted by the converting means is displayed on the display.
Depends on the display device by referring to the device profile
Color conversion means for converting into a color signal
The image processing apparatus according to claim 1 or 2. 4. The color tone of the input image and the display image match each other.
Is an image processing method that performs conversion processing according to ambient light.
Input process of inputting white information and ambient light information of the display device
And multiple combinations of white information and ambient light information of the display device
Refer to the holding means that holds the adaptation ratio corresponding to
Corresponds to the input white information of the display device and ambient light information.
A determination step of determining a that adaptation ratio, based on the determined adaptation ratio, white information of the display device
A calculation step of calculating a reference white value from broadcast and the ambient light information, the input image based on the calculated reference white value shown
Image processing method characterized by having a conversion step of converting to image signals. 5. A detection step for detecting ambient light information is further provided.
The image processing method according to claim 4, characterized in that it has. 6. The white information of the display device is the display device.
Obtained from the Oki profile, The image signal converted by the conversion step is displayed on the display.
Depends on the display device by referring to the device profile
Further comprising a color conversion process for converting into a color signal
The image processing method according to claim 4 or 5. 7. A conversion using the calculated reference white value
Uses the conversion formula according to the Von Kries formula
The image processing according to any one of claims 4 to 6, characterized in that
Method.