JP6772550B2 - Projector and projector control method - Google Patents

Description

The present invention relates to a technique of detecting the color of the reflected light from the projection surface and reflecting it in the color correction of the image projected on the projection surface.

Some projectors are equipped with a function for correcting changes in the color of the projected image due to changes in the color of the projection surface or the performance of the projector over time. Further, there is also a technique for correcting a color change of a projected image caused by ambient light such as sunlight, as described in Patent Documents 1 and 2.

Japanese Unexamined Patent Publication No. 2011-13443 Patent No. 3800326

In the techniques of Patent Documents 1 and 2, the color of light from the projection surface is detected by a color sensor, and the color information (for example, RGB value) indicating the detected result is the tristimulus value in the XYZ color system (hereinafter simply "three"). It is converted to "stimulus value"). However, it is difficult to perform this conversion while maintaining the color identity. The reason is that there is no linear relationship between the color matching function and the spectral sensitivity.

FIG. 4 is a diagram showing an example of the color matching function and the spectral sensitivity of the color sensor. In the graph of color matching function and spectral sensitivity in FIG. 4, the horizontal axis represents wavelength (λ [nm]) and the vertical axis represents spectral sensitivity (relative value). The color matching function is obtained based on the results of psychological color matching experiments, whereas the spectral sensitivity of a color sensor is determined by the optical properties of the color sensor. Each of the X, Y, and Z values included in the tristimulus values and the RGB value satisfy the relationship of the following equation (1). In addition, k1 to k9 are coefficients.

That is, in order to convert the RGB value into a tristimulus value while maintaining the color identity, the color matching functions x (λ), y (λ), z (λ) and the spectral sensitivity r of the color sensor r ( It is necessary that λ), g (λ), and b (λ) satisfy the relationship of the following equation (2) at least in the visible light region. x (λ), y (λ), and z (λ) are functions representing the values of X, Y, and Z with the wavelength λ as a variable, respectively. r (λ), g (λ), and b (λ) are functions representing the values of R, G, and B with the wavelength λ as a variable, respectively. Here, the visible light region refers to a wavelength region of 400 nm or more and 700 nm or less.
x (λ) = k1 · r (λ) + k2 · g (λ) + k3 · b (λ)
y (λ) = k4 · r (λ) + k5 · g (λ) + k6 · b (λ) ... (2)
z (λ) = k7 ・ r (λ) + k8 ・ g (λ) + k9 ・ b (λ)

Without a linear relationship between the color matching function and the spectral sensitivity, it is difficult to satisfy Eq. (2) over the entire visible light region.
The present invention has been made in view of the above circumstances, and one of the objects thereof is to improve the accuracy of conversion from color information indicating the color of reflected light from a projection surface to tristimulus values.

In order to achieve the above object, the projector according to the present invention is a projector that projects an image on a projection surface, and a projection unit that projects light of a plurality of colors on the projection surface and each of the plurality of colors. A color detection unit that detects the color of the reflected light from the projection surface and outputs color information indicating the detection result, and parameters for converting the color information into tristimulus values for each of the plurality of colors. The storage unit to be stored, the conversion unit that converts the color information output for each color from the color detection unit into tristimulus values by using the corresponding parameters, and the converted tristimulus values. Based on this, a correction unit for correcting the color of the image is provided.

In the projector of the present invention, parameters for converting color information into tristimulus values are stored for each of a plurality of colors of light projected on the projection surface, and the color of the reflected light from the projection surface is detected. The color information indicating the result is converted into a tristimulus value using the corresponding parameters. This makes it easier to bring the color matching function and the spectral sensitivity of the color detection unit closer to a linear relationship in the wavelength range corresponding to each of the plurality of colors. Therefore, the accuracy of conversion of color information into tristimulus values is improved as compared with the case where a common parameter is used in the entire visible light region.

In the present invention, the projection unit may project light limited to a specific wavelength range for each of the plurality of colors on the projection surface.
According to the present invention, light limited to a specific wavelength range for each of a plurality of colors is projected onto a projection surface, and the color of the reflected light from the projection surface is detected to detect the color of the reflected light from the projection surface in the wavelength range corresponding to each color. , It becomes easier to bring the color matching function and the spectral sensitivity of the color detector closer to a more linear relationship.

In the present invention, the projection unit sequentially projects light of each color of the plurality of colors and an image of all black on the projection surface, and the conversion unit projects light of each color of the plurality of colors when the light is projected. After subtracting the color information detected when the all-black image is displayed from the detected color information, it may be converted into a tristimulus value.
According to the present invention, it is possible to correct the color of an image projected on a projection surface while reducing the influence of ambient light.

The present invention can be realized not only as a projector but also as a control method for a projector.

The block diagram which shows the structure of the projector which concerns on one Embodiment of this invention. The flowchart which shows the process about the color correction performed by the projector which concerns on the same embodiment. The figure which shows an example of the process which converts the color information which concerns on this embodiment into a tristimulus value. The figure which shows an example of the color matching function and the spectral sensitivity of a color sensor.

FIG. 1 is a diagram showing a configuration of a projector 1 according to an embodiment of the present invention. In FIG. 1, solid arrows represent signal flows and dashed arrows represent optical paths. The projector 1 has a function of detecting the color of the projection surface SC and performing color correction. Color correction refers to a process for correcting the color of an image projected on the projection surface SC, such as gamma correction.
The projector 1 includes an image signal input unit 10, an image processing unit 20, a projection unit 30, a color detection unit 40, a storage unit 50, a CPU (Central Processing Unit) 60, and an operation input unit 70.
The image signal input unit 10 receives an image signal input from the outside. Hereinafter, the image signal input via the image signal input unit 10 is referred to as an “input image signal”. The image signal input unit 10 has, for example, an input terminal (for example, VGA terminal, USB terminal, wired LAN interface, S terminal, RCA terminal, HDMI (High-Definition Multimedia Interface: registered trademark) terminal), and an A / D converter. Including.

The image processing unit 20 performs predetermined image processing on the input image signal. The image processing unit 20 has, for example, an image processing circuit exemplified by an ASIC (Application Specific Integrated Circuit). The image processing unit 20 realizes a function corresponding to the correction unit 210. The correction unit 210 performs color correction by performing a predetermined process on the input image signal. Hereinafter, the image signal after color correction is referred to as a "corrected image signal".

The projection unit 30 projects an image on the projection surface SC. The projection surface SC is, for example, a screen or a wall surface. The projection unit 30 includes a light source 310, a color separation light guide optical system 320, an optical modulation device 330, a cross dichroic prism 340, and a projection optical system 350.
The light source 310 emits light for projecting an image. The light source 310 includes, for example, a lamp such as a high-pressure mercury lamp, a halogen lamp, or a metal halide lamp, a solid-state light source such as an LED (Light Emitting Diode) or a laser diode, and a drive circuit thereof. In the present embodiment, the light source 310 emits white light having a component in the entire visible light region.

In the color separation light guide optical system 320, the light emitted by the light source 310 is red light (hereinafter referred to as “R light”), green light (hereinafter referred to as “G light”), and blue light (hereinafter referred to as “B light”). ) Is separated into three colored lights, and these are guided to the optical modulator 330. The color-separated light guide optical system 320 includes, for example, optical members such as a dichroic mirror, a reflection mirror, and a relay lens. B light is colored light having a component in a wavelength range of at least 400 nm or more and 500 nm or less. G light is colored light having a component in a wavelength range of at least 500 nm or more and 600 nm or less. R light is colored light having a component in a wavelength range of at least 600 nm or more and 700 nm or less. However, the B light, the G light, and the R light may have components other than the above-mentioned wavelength range.

The light modulation device 330 modulates the light incident from the color-separated light guide optical system 320 according to the corrected image signal to form a color image. The light modulator 330 includes, here, the light modulators 331R, 331G, 331B. The light modulator 331R modulates the R light according to the corrected image signal. The light modulator 331G modulates the G light according to the corrected image signal. The light modulator 331B modulates the B light according to the corrected image signal. The light modulators 331R, 331G, and 331B include, here, a liquid crystal panel and a drive circuit of the liquid crystal panel. It is also possible to block one or two color lights out of the three color lights separated by the color separation light guide optical system 320 by the light modulation device 330. In this case, the color separation light guide optical system 320 and the optical modulation device 330 function as wavelength limiting means for limiting the wavelength range of the incident light to a specific wavelength range.

The cross dichroic prism 340 synthesizes the color light (R light, G light, and B light) modulated by the light modulation device 330 to form a color image.
The projection optical system 350 projects a color image (colored light) formed by the cross dichroic prism 340 onto the projection surface SC. The projection optical system 350 includes, for example, a projection lens.

The color detection unit 40 detects the color of the projection surface SC for each of a plurality of colors. Here, the color detection unit 40 mainly detects the color sensor 410R for detecting the color of R light, the color sensor 410G mainly for detecting the color of G light, and the color detection unit 40 mainly for detecting the color of B light. Includes color sensor 410B. The color sensor 410R is a sensor having the strongest sensitivity to the R light component, detects the color of the light reflected from the projection surface SC, and outputs color information indicating the detected result. The color sensor 410R outputs color information according to the intensity of each reflected light of R light, G light, and B light. The color sensor 410G is a sensor having the strongest sensitivity to the G light component, detects the color of the light reflected from the projection surface SC, and outputs color information indicating the detected result. The color sensor 410G outputs color information according to the intensity of each reflected light of R light, G light, and B light. The color sensor 410B is a sensor having the strongest sensitivity to the component of B light, detects the color of the light reflected from the projection surface SC, and outputs color information indicating the detected result. The color sensor 410B outputs color information according to the intensity of each reflected light of R light, G light, and B light. The color information is an RGB value in this embodiment.

The storage unit 50 stores parameters for converting color information into tristimulus values in the XYZ color system for each of a plurality of colors. Here, the storage unit 50 stores a red parameter 510R for converting color information corresponding to red, a green parameter 510G corresponding to green, and a blue parameter 510B corresponding to blue. The storage unit 50 is, for example, a semiconductor memory.

The CPU 60 is a control device that controls each part of the projector 1. The CPU 60 realizes a function corresponding to the conversion unit 610 and the correction value calculation unit 620.
The conversion unit 610 converts the color information output from the color detection unit 40 for each color for each of the plurality of colors into tristimulus values using the parameters stored in the storage unit 50 and corresponding to each. The conversion unit 610 converts the color information corresponding to red into tristimulus values using the red parameter 510R. The conversion unit 610 converts the color information corresponding to green into a tristimulus value using the green parameter 510G. The conversion unit 610 converts the color information corresponding to blue into a tristimulus value using the blue parameter 510B.

The correction value calculation unit 620 calculates the correction value in the color correction based on the tristimulus values converted by the conversion unit 610. The correction value calculation unit 620 calculates a correction value for setting the tristimulus value converted by the conversion unit 610 as a target value.
The correction unit 210 of the image processing unit 20 sets the correction value calculated by the correction value calculation unit 620 and performs color correction.

The operation input unit 70 receives the input of the user's operation. The operation input unit 70 receives an operation input via, for example, an operator provided in the main body of the projector 1 or a remote controller.

FIG. 2 is a flowchart showing a process related to color correction performed by the projector 1.
The user performs an operation for starting the color correction on the operation input unit 70. The CPU 60 receives the input of this operation via the operation input unit 70. Then, the projection unit 30 projects the all-black image onto the projection surface SC (step S1). The all-black image is an image in which the entire projection surface SC is displayed in black. Black is (0,0,0) when expressed in RGB values. Therefore, the projection unit 30 projects an all-black image by blocking the light from the light source 310 in the light modulators 331R, 331G, and 331B. Alternatively, the projection unit 30 may project an all-black image by turning off the light source 310.

Next, the color detection unit 40 detects the color of the reflected light from the projection surface SC when the all-black image is projected by using the color sensors 410R, 410G, 410B (step S2). The color detected when the all-black image is displayed can be regarded as the color of the ambient light (for example, light including sunlight and illumination light) around the projector 1. The color information output by the color sensors 410R, 410G, 410B is represented as (Renv, Genv, Benv). In general, ambient light contains components in a wide wavelength range.

Next, the projection unit 30 projects a blue monochromatic image onto the projection surface SC (step S3). The blue monochromatic image is an image displayed in blue by projecting B light onto the projection surface SC. The projection unit 30 projects a monochromatic blue image by transmitting the B light in the light modulator 331B and blocking the light from the light source 310 in the light modulators 331R and 331G, for example.

Next, the color detection unit 40 detects the color of the reflected light from the projection surface SC when the blue monochromatic image is projected by using the color sensors 410R, 410G, 410B (step S4). The color detected when the blue monochromatic image is displayed can be regarded as the color of the light obtained by mixing the reflected light from the projection surface SC and the ambient light around the projector 1. The color information output by the color sensors 410R, 410G, 410B at this time is represented as (R'blue, G'blue, B'blue). Then, the color detection unit 40 subtracts the ambient light color information (Renv, Genv, Benv) detected in step S2 from the color information (R'blue, G'blue, B'blue) to obtain a single blue color. The color information (Rblue, Gblue, Bblue) of the reflected light when the image is displayed is calculated.

Next, the CPU 60 converts the color information detected in step S4 into tristimulus values (Xblue, Yblue, Zblue) using the blue parameter 510B stored in the storage unit 50 (step S5). Specifically, the CPU 60 performs the calculation of the following equation (3).

The coefficients of k1blue to k9blue are adjusted so that the spectral sensitivities of the color sensors 410R, 410G, and 410B approach the color matching function described in FIG. 4 with respect to light of about 400 nm ≦ λ ≦ about 500 nm. An example of the spectral sensitivity to B light is shown in FIG. 3 (A). X', Y', and Z'in the graph of FIG. 3A have a peak at about 450 nm, and the color matching function X with respect to B light such that the intensity gradually decreases as the wavelength deviates from 450 nm. It shows the sensitivities of Y and Z. Further, Xblue, Yblue, and Zblue in the graph represent the spectral sensitivities obtained by applying the optimum coefficients k1blue to k9blue to the spectral sensitivities of the color sensors 410R, 410G, and 410B for the same B light. As can be seen from the graph of FIG. 3 (A), the color matching functions X, Y, Z and the stimulus values Xblue, Yblue, Zblue have very close spectral sensitivities to the light of about 400 nm ≦ λ ≦ about 500 nm. have. Therefore, within this wavelength range, color information can be converted into tristimulus values with high accuracy.

Next, the projection unit 30 projects a green monochromatic image onto the projection surface SC (step S6). The green monochromatic image is an image displayed in green by projecting G light onto the projection surface SC. The projection unit 30 projects a green monochromatic image by transmitting G light through the light modulator 331G and blocking the light from the light source 310 by the light modulators 331R and 331B, for example.

Next, the color detection unit 40 detects the color of the reflected light from the projection surface SC when the green monochromatic image is projected by using the color sensors 410R, 410G, 410B (step S7). The color detected when the green monochromatic image is displayed can be regarded as the color of the light obtained by mixing the reflected light from the projection surface SC and the ambient light around the projector 1. The color information output by the color sensors 410R, 410G, 410B at this time is represented as (R'green, G'green, B'green). Then, the color detection unit 40 subtracts the ambient light color information (Rev, Genv, Benv) detected in step S2 from the color information (R'green, G'green, B'green) to obtain a single green color. The color information (Rgreen, Ggreen, Bgreen) of the reflected light when the image is displayed is calculated.

Next, the CPU 60 converts the color information detected in step S6 into tristimulus values (Xgreen, Ygreen, Zgreen) using the green parameter 510G stored in the storage unit 50 (step S8). Specifically, the CPU 60 performs the calculation of the following equation (4).

The coefficients of k1green to k9green are adjusted so that the spectral sensitivities of the color sensors 410R, 410G, and 410B approach the color matching function described in FIG. 4 with respect to light of about 500 nm ≦ λ ≦ about 600 nm. An example of the spectral sensitivity to G light is shown in FIG. 3 (B). X', Y', and Z'in the graph of FIG. 3B have peaks at about 550 nm, and the intensities gradually decrease as the wavelength deviates from 550 nm. , Z sensitivity is shown. Further, Xgreen, Ygreen, and Zgreen in the graph represent the spectral sensitivities obtained by applying the optimum coefficients k1green to k9green to the spectral sensitivities of the color sensors 410R, 410G, and 410B for the same G light. As can be seen from the graph of FIG. 3B, the color matching functions X, Y, Z and the stimulus values Xgreen, Ygreen, Zgreen are very close to each other for light of about 500 nm ≦ λ ≦ about 600 nm. have. Therefore, within this wavelength range, color information can be converted into tristimulus values with high accuracy.

Next, the projection unit 30 projects a monochromatic red image onto the projection surface SC (step S9). The red monochromatic image is an image displayed in red by projecting R light onto the projection surface SC. The projection unit 30 projects a monochromatic red image by transmitting R light in the light modulator 331R and blocking the light from the light source 310 in the light modulators 331G and 331B, for example.

Next, the color detection unit 40 detects the color of the reflected light from the projection surface SC when the red monochromatic image is projected by using the color sensors 410R, 410G, 410B (step S10). The color detected when the red monochromatic image is displayed can be regarded as the color of the light obtained by mixing the reflected light from the projection surface SC and the ambient light around the projector 1. At this time, the color information output by the color sensors 410R, 410G, 410B is expressed as (R'red, G'red, B'red). Then, the color detection unit 40 subtracts the ambient light color information (Renv, Genv, Benv) detected in step S2 from the color information (R'red, G'red, B'red) to obtain a single red color. The color information (Rred, Gred, Red) of the reflected light when the image is displayed is calculated.

Next, the CPU 60 converts the color information detected in step S8 into tristimulus values (Xred, Yred, Zred) using the red parameter 510R stored in the storage unit 50 (step S11). Specifically, the CPU 60 performs the calculation of the following equation (5).

The coefficients of k1red to k9red are adjusted so that the spectral sensitivities of the color sensors 410R, 410G, and 410B approach the color matching function described in FIG. 4 with respect to light of about 600 nm ≦ λ ≦ about 700 nm. An example of the spectral sensitivity to R light is shown in FIG. 3 (C). X', Y', and Z'in the graph of FIG. 3C have peaks at about 610 nm, and the intensities gradually decrease as the wavelength deviates from 610 nm. , Z sensitivity is shown. Further, Xred, Yred, and Zred in the graph represent the spectral sensitivities obtained by applying the optimum coefficients k1red to k9red to the spectral sensitivities of the color sensors 410R, 410G, and 410B for the same R light. As can be seen from the graph of FIG. 3C, the color matching functions X, Y, Z and the stimulus values Xred, Yred, Zred have very close spectral sensitivities with respect to light of about 600 nm ≦ λ ≦ about 700 nm. have. Therefore, within this wavelength range, color information can be converted into tristimulus values with high accuracy.

The CPU 60 calculates a correction value using the tristimulus values obtained by the conversion in steps S5, S8, and S11 (step S12). Here, the CPU 60 calculates a correction value by additive mixing based on the tristimulus values (Xblue, Yblue, Zblue), (Xgreen, Ygreen, Zgreen), and (Xred, Yred, Zred). For example, the CPU 60 adds the tristimulus values (Xblue, Yblue, Zblue), (Xgreen, Ygreen, Zgreen), and (Xred, Yred, Zred) to calculate the tristimulus value of white light. Then, the CPU 60 calculates a correction value for setting the tristimulus value as a target value. The image processing unit 20 sets the calculated correction value. The setting referred to here means, for example, a process of writing a correction value to the internal memory of the image processing unit 20.
By the above processing, the setting of the correction value related to the color correction is completed.

After that, when the input image signal is input via the image signal input unit 10, the image processing unit 20 performs color correction for correcting the input image signal based on the set correction value (step S13). The image processing unit 20 uses this correction value until the next correction value is updated. Then, the image processing unit 20 outputs the corrected image signal to the optical modulator 330 (optical modulators 331R, 331G, 331B). The projection unit 30 drives the optical modulation device 330 based on the corrected image signal to project an image corresponding to the corrected image signal on the projection surface SC (step S14).

As described above, the projector 1 stores parameters for converting color information into tristimulus values for each of a plurality of colors of light projected on the projection surface SC. Further, the projector 1 detects the color of the reflected light from the projection surface SC for each of a plurality of colors, and converts the color information indicating the detection result into tristimulus values by using the parameters corresponding to each. .. As a result, the projector 1 can convert to tristimulus values by parameters adjusted based on the relationship between the color matching function of each wavelength range of B light, G light, and R light and the spectral characteristics. Therefore, as described in FIG. 3, in the wavelength range corresponding to each color of a plurality of colors, the color matching function and the spectral sensitivity have a linear relationship as compared with the case where a common parameter is used in the entire visible light range. Get closer. Therefore, the accuracy of conversion from the color information to the tristimulus values in the projector 1 is improved.

The present invention can be implemented in a form different from the above-described embodiment. In addition, the following modifications may be combined as appropriate.
The wavelength limiting means for limiting the wavelength range of light may be an optical modulation device other than the liquid crystal panel. Further, for example, when the optical modulation device is a DMD (Digital Mirror Device), the color wheel and the DMD may function as wavelength limiting means. The color wheel is, for example, a disk in which red, blue, and green filters are integrated. In this case, the light emitted by the light source becomes R light, B light, and G light by passing through the rotating color wheel. The light transmitted through the color wheel enters the projection optical system via the DMD.

A part of the configuration or operation described in the above-described embodiment may be omitted or changed. For example, if the projector 1 does not perform color correction by reducing the influence of ambient light, it is not necessary to project an all-black image and detect a color when the all-black image is projected. Further, the projector 1 may sequentially project an all-black image, a blue monochromatic image, a green monochromatic image, and a red monochromatic image in a different order from the above-described embodiment, or may sequentially project a blue monochromatic image, a green monochromatic image, and a green monochromatic image. Two or more of the monochromatic red images may be projected at the same time.

Further, the color sensor to be included in the color detection unit 40 does not have to match the number of colored lights. For example, the color detection unit 40 may include a color sensor having the strongest sensitivity to BG (blue green) light in addition to R, G, and B. As the number of color sensors included in the color detection unit 40 increases, the accuracy of conversion from color information to tristimulus values may improve. Conversely, the number of color sensors may be less than the number of colored lights. The color detection unit may be configured to include a color sensor having sensitivity to a plurality of colors.

In the above-described embodiment, the wavelength range of each color is limited according to the wavelength range corresponding to red, green, and blue, but this color and wavelength range are merely examples. For example, the wavelength range of each color may be limited according to the wavelength range corresponding to other colors such as yellow and cyan. Further, the wavelength ranges corresponding to each of the two or more colors may partially overlap each other.

The hardware configuration of the projector 1 is not limited to that illustrated in the embodiment. The projector 1 may have any hardware configuration as long as it can realize the required functions.

1 ... Projector, 10 ... Image signal input unit, 20 ... Image processing unit, 210 ... Correction unit, 30 ... Projection unit, 310 ... Light source, 320 ... Color separation light guide optical system, 330 ... Optical modulator, 331R, 331G, 331B ... Optical modulator, 340 ... Cross dichroic prism, 350 ... Projection optical system, 40 ... Color detector, 410R, 410G, 410B ... Color sensor, 50 ... Storage unit, 510R ... Red parameter, 510G ... Green parameter, 510B ... Blue parameter, 60 ... CPU, 610 ... Conversion unit, 620 ... Correction value calculation unit, 70 ... Operation input unit.

Claims (5)

A projector that projects an image onto the projection surface.
A projection unit that projects light of multiple colors onto the projection surface,
A color detection unit that detects the color of the reflected light from the projection surface with a color sensor for each of the plurality of colors and outputs color information indicating the detection result.
A storage unit that stores a conversion matrix that is different for each of the color components of the plurality of colors for converting the color information into tristimulus values.
A conversion unit that converts the color information output from the color detection unit for each color component into tristimulus values for each color component using different conversion matrices.
A projector including a correction unit that corrects the color of the image based on the converted tristimulus values for each color component. The projector according to claim 1, wherein the correction unit corrects the color of the image by using the tristimulus value obtained by additively mixing the tristimulus values for each color component. The projector according to claim 2, wherein the projection unit projects light limited to a specific wavelength range for each of the plurality of colors onto the projection surface. The projection unit sequentially projects light of each of the plurality of colors and an all-black image onto the projection surface.
The conversion unit subtracts the color information detected when the all-black image is displayed from the color information detected when the light of each of the plurality of colors is projected, and then the conversion unit has three. The projector according to any one of claims 1 to 3, wherein the projector is converted into a stimulus value. It is a control method of a projector that projects an image on the projection surface.
A step of projecting light of multiple colors onto the projection surface, and
A step of detecting the color of the reflected light from the projection surface with a color sensor for each of the plurality of colors and outputting color information indicating the detected result.
A step of storing a transformation matrix different for each of the color components of the plurality of colors for converting the color information into tristimulus values, and
In the step of outputting the color information, the step of converting the color information output for each color component into tristimulus values for each color component using different transformation matrices, and
A method of controlling a projector including a step of correcting the color of the image based on the converted tristimulus values for each of the color components.