# Patent

## Title
Image processing system, projector, and image processing method

## Abstract

A projector includes an image distortion sensing section which generates image distortion sensing information, an environmental influence sensing section which generates environmental influence sensing information, a projection area information generation section which generates projection area information, an image distortion correction section which corrects distortion of a projection image and generates correction information indicating the degree of correction, a display area information generation section which generates display area information indicating the display area of the projection image after distortion correction based on the projection area information and the correction information, an environmental influence reduction section which performs processing of reducing environmental influence, a projection section which projects the projection image, and a differential image generation section which generates a differential image.

## Background
Japanese Patent Application No. 2005-36172, filed on Feb. 14, 2005, is hereby incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
The present invention relates to an image processing system which performs projection image distortion correction processing and environmental influence reduction processing, a projector, and an image processing method.
In recent years, a projector has been proposed which corrects distortion of a projection image and reduces environmental influence (e.g. influence of external light or influence of screen color) by projecting an image onto a screen using a projector including a sensor, sensing the projected image using the sensor, and performing image processing.
A related-art projector separately performs the projection image distortion correction processing and the environmental influence reduction processing. Therefore, a related-art projector takes time for the projection image distortion correction processing and the environmental influence reduction processing.
In order to reduce the time required for such calibration processing, JP-A-2003-339056 reduces the time required for the environmental influence reduction processing by causing a projector to generate visual environment estimation data to reduce the number of times the calibration image is projected.
However, when distortion of the projection image has been corrected, the projection image may not be displayed in the area in which the projection image is originally displayed due to distortion correction. In this case, even if the environmental influence reduction processing is performed by using the sensing information of that area, the environmental influence may not be appropriately reduced from the projection image after distortion correction.
For example, JP-A-2004-48694 discloses a projector which determines the visual environment of the projection area based on sensing information of the selected projection area and corrects an image in order to project an image in an area without an obstacle.
However, since the projector disclosed in JP-A-2004-48694 does not take into consideration the position and the shape of the projection image after distortion correction, the environmental influence may not be appropriately reduced.
The position and the shape of the projection image may change due to a zoom function. A projector must appropriately perform the environmental influence reduction processing even in such a case.
SUMMARY
According to a first aspect of the invention, there is provided an image processing system, comprising:
an image distortion sensing section which senses an area including at least a part of a projection image projected onto a projection target area to generate image distortion sensing information;
an environmental influence sensing section which senses a specific area of the projection image to generate environmental influence sensing information indicating a brightness index value in the specific area;
an image distortion correction section which corrects distortion of the projection image;
an environmental influence reduction section which performs processing of reducing environmental influence caused by a difference between an ideal environment and an actual environment; and
a projection section which projects a single-color red image, a single-color green image, a single-color blue image, and a solid black image as the projection image at different times;
the environmental influence sensing section sensing an area of the projection image always included in an image after image distortion correction as the specific area to generate the environmental influence sensing information of each of the single-color red image, the single-color green image, the single-color blue image, and the solid black image; and
the environmental influence reduction section performing the processing of reducing the environmental influence based on the environmental influence sensing information.
According to a second aspect of the invention, there is provided an image processing system, comprising:
an image distortion sensing section which senses an area including at least a part of a projection image projected onto a projection target area to generate image distortion sensing information;
an environmental influence sensing section which senses a specific area of the projection image near a center of the projection image to generate environmental influence sensing information indicating a brightness index value in the specific area;
a projection area information generation section which generates projection area information indicating a position of the projection image in a sensing image of the image distortion sensing section based on the image distortion sensing information;
an image distortion correction section which corrects distortion of the projection image and generates correction information indicating a degree of the correction;
a display area information generation section which generates display area information indicating a display area of the projection image in the sensing image after distortion correction based on the projection area information and the correction information;
an environmental influence reduction section which performs processing of reducing environmental influence caused by a difference between an ideal environment and an actual environment;
a projection section which projects a single-color red image, a single-color green image, a single-color blue image, a solid black image, and a multi-color image including one of red, green, and blue and black as the projection image at different times; and
a differential image generation section which generates a specific differential image;
the multi-color image including a center image positioned near a center of the multi-color image, a peripheral image positioned at periphery of the center image, and a background image other than the center and peripheral images, the center and peripheral images being black and the background image being a single color other than black, or the center and peripheral images being a single color other than black and the background image being black;
the image distortion sensing section sensing an area including at least a part of the multi-color image and the single-color image of red, green, blue, or black to generate the image distortion sensing information of each of the images;
the environmental influence sensing section sensing the specific area of the single-color red image, the single-color green image, the single-color blue image, and the solid black image to generate the environmental influence sensing information of each of the images;
the differential image generation section generating a pattern differential image based on the image distortion sensing information of the multi-color image and the image distortion sensing information of one of the single-color images;
the projection area information generation section generating center area information indicating a position of the center image in the sensing image and peripheral area information indicating a position of the peripheral image in the sensing image based on the pattern differential image, and generating the projection area information based on the center area information and the peripheral area information; and
the environmental influence reduction section performing the processing of reducing the environmental influence based on the environmental influence sensing information and the display area information.
According to a third aspect of the invention, there is provided a projector comprising any of the above-described image processing systems.
According to a fourth aspect of the invention, there is provided a program readable by a computer including an image distortion sensing section, an environmental influence sensing section, and a projection section, the program causing the computer to function as:
an image distortion sensing control section which causes an image distortion sensing section to sense an area including at least a part of a projection image projected onto a projection target area to generate image distortion sensing information;
an environmental influence sensing control section which causes an environmental influence sensing section to sense a specific area of the projection image near a center of the projection image to generate environmental influence sensing information;
a projection area information generation section which generates projection area information indicating a position of the projection image in a sensing image of the image distortion sensing section based on the image distortion sensing information;
an image distortion correction section which corrects distortion of the projection image and generates correction information indicating a degree of the correction;
a display area information generation section which generates display area information indicating a display area of the projection image in the sensing image after distortion correction based on the projection area information and the correction information;
an environmental influence reduction section which performs processing of reducing environmental influence caused by a difference between an ideal environment and an actual environment;
a projection control section which causes a projection section to project a single-color red image, a single-color green image, a single-color blue image, a solid black image, and a multi-color image including one of red, green, and blue and black as the projection image at different times; and
a differential image generation section which generates a specific differential image,
the multi-color image including a center image positioned near a center of the multi-color image, a peripheral image positioned at periphery of the center image, and a background image other than the center and peripheral images, the center and peripheral images being black and the background image being a single color other than black, or the center and peripheral images being a single color other than black and the background image being black;
the image distortion sensing section sensing an area including at least a part of the multi-color image and the single-color image of red, green, blue, or black to generate the image distortion sensing information of each of the images;
the environmental influence sensing section sensing the specific area of the single-color red image, the single-color green image, the single-color blue image, and the solid black image to generate the environmental influence sensing information of each of the images;
the differential image generation section generating a pattern differential image based on the image distortion sensing information of the multi-color image and the image distortion sensing information of one of the single-color images;
the projection area information generation section generating center area information indicating a position of the center image in the sensing image and peripheral area information indicating a position of the peripheral image in the sensing image based on the pattern differential image, and generating the projection area information based on the center area information and the peripheral area information; and
the environmental influence reduction section performing the processing of reducing the environmental influence based on the environmental influence sensing information and the display area information.
According to a fifth aspect of the invention, there is provided an information storage medium storing the above-described program.
According to a sixth aspect of the invention, there is provided an image processing method utilizing a computer including an image distortion sensing section, an environmental influence sensing section, a processing section, and a projection section, the method comprising:
causing the projection section to project a single-color red image, a single-color green image, a single-color blue image, a solid black image, and a multi-color image including one of red, green, and blue and black as the projection image at different times, the multi-color image including a center image positioned near a center of the multi-color image, a peripheral image positioned at periphery of the center image, and a background image other than the center image and the peripheral image;
causing the image distortion sensing section to sense an area including at least a part of the single-color red image, the single-color green image, the single-color blue image, or the solid black image projected onto a projection target area to generate first image distortion sensing information, to sense an area including at least a part of the multi-color image projected onto the projection target area to generate second image distortion sensing information;
causing the environmental influence sensing section to sense a specific area near the center of the single-color green image projected onto the projection target area to generate first environmental influence sensing information, to sense the specific area of the single-color red image projected onto the projection target area to generate second environmental influence sensing information, to sense the specific area of the single-color blue image projected onto the projection target area to generate third environmental influence sensing information, and to sense the specific area of the solid black image projected onto the projection target area to generate fourth environmental influence sensing information; and
causing the processing section to generate a pattern differential image based on the first and second image distortion sensing information, to generate center area information indicating a position of the center image in the sensing image of the image distortion sensing section and peripheral area information indicating a position of the peripheral image in the sensing image based on the pattern differential image, to generate projection area information indicating a position of the projection image in the sensing image based on the center area information and the peripheral area information, to generate correction information indicating a degree of correction of distortion of the projection image based on the projection area information, to generate display area information indicating a display area of the projection image in the sensing image after distortion correction based on the projection area information and the correction information, to correct image information based on the correction information so that image distortion is corrected, and to correct the image information based on the first to fourth environmental influence sensing information and the display area information so that environmental influence caused by a difference between an ideal environment and an actual environment is reduced.



BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
FIG. 1 is a schematic diagram showing an image projection state according to a first embodiment.
FIG. 2 is a functional block diagram of a projector according to the first embodiment.
FIG. 3 is a hardware block diagram of the projector according to the first embodiment.
FIG. 4 is a flowchart showing the flow of image processing from preprocessing to generation of projection target area information according to the first embodiment.
FIG. 5 shows a checkered pattern image according to the first embodiment.
FIG. 6 is a flowchart showing the flow of image processing from generation of correction information to image projection according to the first embodiment.
FIG. 7 is a flowchart showing the flow of image processing from generation of correction information to image projection according to a second embodiment.



DETAILED DESCRIPTION OF THE EMBODIMENT
The invention may provide an image processing system, a projector, a program, an information storage medium, and an image processing method capable of more appropriately performing environmental influence reduction processing when performing projection image distortion correction processing.
According to one embodiment of the invention, there is provided an image processing system, comprising:
an image distortion sensing section which senses an area including at least a part of a projection image projected onto a projection target area to generate image distortion sensing information;
an environmental influence sensing section which senses a specific area of the projection image to generate environmental influence sensing information indicating a brightness index value in the specific area;
an image distortion correction section which corrects distortion of the projection image;
an environmental influence reduction section which performs processing of reducing environmental influence caused by a difference between an ideal environment and an actual environment; and
a projection section which projects a single-color red image, a single-color green image, a single-color blue image, and a solid black image as the projection image at different times;
the environmental influence sensing section sensing an area of the projection image always included in an image after image distortion correction as the specific area to generate the environmental influence sensing information of each of the single-color red image, the single-color green image, the single-color blue image, and the solid black image; and
the environmental influence reduction section performing the processing of reducing the environmental influence based on the environmental influence sensing information.
According to one embodiment of the invention, there is provided a projector comprising the above-described image processing system.
In these embodiments, the image processing system and the like can more appropriately perform the environmental influence reduction processing when performing the projection image distortion correction processing by causing the environmental influence sensing section to sense the specific area of the projection image always included in the image after image distortion correction.
According to one embodiment of the invention, there is provided an image processing system, comprising:
an image distortion sensing section which senses an area including at least a part of a projection image projected onto a projection target area to generate image distortion sensing information;
an environmental influence sensing section which senses a specific area of the projection image near a center of the projection image to generate environmental influence sensing information indicating a brightness index value in the specific area;
a projection area information generation section which generates projection area information indicating a position of the projection image in a sensing image of the image distortion sensing section based on the image distortion sensing information;
an image distortion correction section which corrects distortion of the projection image and generates correction information indicating a degree of the correction;
a display area information generation section which generates display area information indicating a display area of the projection image in the sensing image after distortion correction based on the projection area information and the correction information;
an environmental influence reduction section which performs processing of reducing environmental influence caused by a difference between an ideal environment and an actual environment;
a projection section which projects a single-color red image, a single-color green image, a single-color blue image, a solid black image, and a multi-color image including one of red, green, and blue and black as the projection image at different times; and
a differential image generation section which generates a specific differential image;
the multi-color image including a center image positioned near a center of the multi-color image, a peripheral image positioned at periphery of the center image, and a background image other than the center and peripheral images, the center and peripheral images being black and the background image being a single color other than black, or the center and peripheral images being a single color other than black and the background image being black;
the image distortion sensing section sensing an area including at least a part of the multi-color image and the single-color image of red, green, blue, or black to generate the image distortion sensing information of each of the images;
the environmental influence sensing section sensing the specific area of the single-color red image, the single-color green image, the single-color blue image, and the solid black image to generate the environmental influence sensing information of each of the images;
the differential image generation section generating a pattern differential image based on the image distortion sensing information of the multi-color image and the image distortion sensing information of one of the single-color images;
the projection area information generation section generating center area information indicating a position of the center image in the sensing image and peripheral area information indicating a position of the peripheral image in the sensing image based on the pattern differential image, and generating the projection area information based on the center area information and the peripheral area information; and
the environmental influence reduction section performing the processing of reducing the environmental influence based on the environmental influence sensing information and the display area information.
According to one embodiment of the invention, there is provided a projector comprising the above-described image processing system.
According to one embodiment of the invention, there is provided a program readable by a computer including an image distortion sensing section, an environmental influence sensing section, and a projection section, the program causing the computer to function as:
an image distortion sensing control section which causes an image distortion sensing section to sense an area including at least a part of a projection image projected onto a projection target area to generate image distortion sensing information;
an environmental influence sensing control section which causes an environmental influence sensing section to sense a specific area of the projection image near a center of the projection image to generate environmental influence sensing information;
a projection area information generation section which generates projection area information indicating a position of the projection image in a sensing image of the image distortion sensing section based on the image distortion sensing information;
an image distortion correction section which corrects distortion of the projection image and generates correction information indicating a degree of the correction;
a display area information generation section which generates display area information indicating a display area of the projection image in the sensing image after distortion correction based on the projection area information and the correction information;
an environmental influence reduction section which performs processing of reducing environmental influence caused by a difference between an ideal environment and an actual environment;
a projection control section which causes a projection section to project a single-color red image, a single-color green image, a single-color blue image, a solid black image, and a multi-color image including one of red, green, and blue and black as the projection image at different times; and
a differential image generation section which generates a specific differential image,
the multi-color image including a center image positioned near a center of the multi-color image, a peripheral image positioned at periphery of the center image, and a background image other than the center and peripheral images, the center and peripheral images being black and the background image being a single color other than black, or the center and peripheral images being a single color other than black and the background image being black;
the image distortion sensing section sensing an area including at least a part of the multi-color image and the single-color image of red, green, blue, or black to generate the image distortion sensing information of each of the images;
the environmental influence sensing section sensing the specific area of the single-color red image, the single-color green image, the single-color blue image, and the solid black image to generate the environmental influence sensing information of each of the images;
the differential image generation section generating a pattern differential image based on the image distortion sensing information of the multi-color image and the image distortion sensing information of one of the single-color images;
the projection area information generation section generating center area information indicating a position of the center image in the sensing image and peripheral area information indicating a position of the peripheral image in the sensing image based on the pattern differential image, and generating the projection area information based on the center area information and the peripheral area information; and
the environmental influence reduction section performing the processing of reducing the environmental influence based on the environmental influence sensing information and the display area information.
According to one embodiment of the invention, there is provided an information storage medium storing the above-described program.
According to one embodiment of the invention, there is provided an image processing method utilizing a computer including an image distortion sensing section, an environmental influence sensing section, a processing section, and a projection section, the method comprising:
causing the projection section to project a single-color red image, a single-color green image, a single-color blue image, a solid black image, and a multi-color image including one of red, green, and blue and black as the projection image at different times, the multi-color image including a center image positioned near a center of the multi-color image, a peripheral image positioned at periphery of the center image, and a background image other than the center image and the peripheral image;
causing the image distortion sensing section to sense an area including at least a part of the single-color red image, the single-color green image, the single-color blue image, or the solid black image projected onto a projection target area to generate first image distortion sensing information, to sense an area including at least a part of the multi-color image projected onto the projection target area to generate second image distortion sensing information;
causing the environmental influence sensing section to sense a specific area near the center of the single-color green image projected onto the projection target area to generate first environmental influence sensing information, to sense the specific area of the single-color red image projected onto the projection target area to generate second environmental influence sensing information, to sense the specific area of the single-color blue image projected onto the projection target area to generate third environmental influence sensing information, and to sense the specific area of the solid black image projected onto the projection target area to generate fourth environmental influence sensing information; and
causing the processing section to generate a pattern differential image based on the first and second image distortion sensing information, to generate center area information indicating a position of the center image in the sensing image of the image distortion sensing section and peripheral area information indicating a position of the peripheral image in the sensing image based on the pattern differential image, to generate projection area information indicating a position of the projection image in the sensing image based on the center area information and the peripheral area information, to generate correction information indicating a degree of correction of distortion of the projection image based on the projection area information, to generate display area information indicating a display area of the projection image in the sensing image after distortion correction based on the projection area information and the correction information, to correct image information based on the correction information so that image distortion is corrected, and to correct the image information based on the first to fourth environmental influence sensing information and the display area information so that environmental influence caused by a difference between an ideal environment and an actual environment is reduced.
In these embodiments, the image processing system and the like can more appropriately perform the environmental influence reduction processing when performing the projection image distortion correction processing by performing the environmental influence reduction processing using the sensing information inside the display area after distortion correction.
In these embodiments, since the image processing system and the like can perform the projection image distortion correction processing and the environmental influence reduction processing by projecting and sensing five types of images, image processing can be more efficiently performed.
Each of the image processing systems, the projectors, the program, the information storage medium and the image processing method may comprise:
a control section which controls a zoom section which adjusts a size of the projection image based on the display area information so that the projection image is projected in an area corresponding to the display area in the projection target area at an optimum size, and generates adjustment information indicating a degree of the adjustment,
wherein the environmental influence reduction section includes:
a sensing information correction section which generates corrected sensing information by determining a change in brightness of the projection image due to the adjustment based on the adjustment information, and correcting information inside the display area included in the environmental influence sensing information corresponding to the change in brightness; and
an image information correction section which corrects image information based on the corrected sensing information so that a color and brightness of the projection image become ideal.
This enables the image processing system and the like to more appropriately perform the environmental influence reduction processing when adjusting the size of the projection image by performing the environmental influence reduction processing using the sensing information inside the display area after size adjustment.
In each of the image processing systems, the projectors, the program, the information storage medium and the image processing method,
the image information correction section may include:
a color correction section which corrects the image information based on ideal color information indicating an ideal color and the corrected sensing information so that the projection image is projected in the ideal color; and
a brightness correction section which corrects the image information corrected by the color correction section based on ideal brightness information indicating ideal brightness and the corrected sensing information so that the projection image is projected at the ideal brightness.
In each of the image processing systems and the projectors,
the environmental influence correction section may include an image information correction section; and
the image information correction section may include:
a color correction section which corrects the image information based on ideal color information indicating an ideal color and the environmental influence sensing information so that the projection image is projected in the ideal color; and
a brightness correction section which corrects the image information corrected by the color correction section based on ideal brightness information indicating ideal brightness and the environmental influence sensing information so that the projection image is projected at the ideal brightness.
This enables the image processing system and the like to generate an appropriate image of which the color and brightness have been adjusted.
In each of the image processing systems, the projectors, the program, the information storage medium and the image processing method,
the brightness correction section may generate corrected sensing information of a solid white image based on the corrected sensing information of the single-color red image, the single-color green image, the single-color blue image, and the single-color black image, and correct the image information corrected by the color correction section by utilizing the corrected sensing information of the solid white image.
In each of the image processing systems and the projectors,
the brightness correction section may generate environmental influence sensing information of a solid white image based on the environmental influence sensing information of the single-color red image, the single-color green image, the single-color blue image, and the single-color black image, and correct the image information corrected by the color correction section by utilizing the environmental influence sensing information of the solid white image.
This enables the image processing system and the like to perform the projection image distortion correction processing and the environmental influence reduction processing by projecting and sensing five types of images by generating the corrected sensing information of the solid white image based on the corrected sensing information of the single-color red image, the single-color green image, the single-color blue image, and the single-color black image so that image processing can be more efficiently performed.
Each of the image processing systems, the projectors, the program, the information storage medium and the image processing method may comprise:
a projection target area information generation section which generates projection target area information indicating a position of the projection target area in the sensing image,
wherein the image distortion sensing section senses an area including at least a part of the solid black image to generate image distortion sensing information of the solid black image;
wherein the differential image generation section generates a brightness differential image based on the image distortion sensing information of the solid black image and the image distortion sensing information of one of the single-color images;
wherein the projection target area information generation section generates the projection target area information based on the brightness differential image and the projection area information; and
wherein the image distortion correction section corrects distortion of the projection image based on the projection target area information and the projection area information.
This enables the image processing system and the like to correct distortion of the projection image by determining distortion of the projection image from the difference in shape between the projection target area and the projection area, for example.
In each of the image processing systems, the projectors, the program, the information storage medium and the image processing method,
the projection section may project a position confirmation image for allowing a user to confirm whether or not the area corresponding to the specific area is projected into the projection target area before projecting the projection image.
This enables the image processing system and the like to sense an image in a state in which the center area is reliably included in the sensing information by using the position confirmation image and allowing the user to confirm whether or not the area corresponding to the center area is positioned inside the projection target area. This enables the image processing system and the like to perform image processing by using appropriate sensing information.
In the image processing systems, the projectors, the program, the information storage medium, and the image processing method, the image distortion correction section may detect a peak position of a brightness index value (e.g. luminance value or illuminance value) based on the image distortion sensing information, and may correct distortion of the projection image based on the peak position.
Embodiments of the invention applied to a projector having an image processing system are described below by way of example, with reference to the accompanying drawings. Note that the embodiments described below do not in any way limit the scope of the invention laid out in the claims herein. In addition, not all of the elements of the embodiments described below should be taken as essential requirements of the invention.
First Embodiment
FIG. 1 is a schematic diagram showing an image projection state according to the first embodiment.
A projector 20 projects an image onto a screen 10 having a projection target area. As a result, a projection image 12 is displayed on the screen 10.
In the first embodiment, a part of the screen 10 is influenced by external light 80 (environmental influence), as shown in FIG. 1. Since the projector 20 obliquely projects an image onto the screen 10, the projected image 12 is distorted so that keystone distortion occurs. As shown in FIG. 1, a part of the projection image 12 is positioned outside the screen 10.
In the first embodiment, the projector 20 includes an image distortion sensor 60 for correcting distortion of the projection image 12, and an environmental influence sensor 62 for reducing environmental influence. The image distortion sensor 60 senses an image distortion sensing area 14 including the projection image 12 projected onto the screen 10 (may be a part of the projection image 12) to generate image distortion sensing information. The environmental influence sensor 62 senses an environmental influence sensing area 15 (specific area) near the center of the projection image 12 to generate environmental influence sensing information.
The projector 20 performs distortion correction processing of the projection image 12 and environmental influence reduction processing almost at the same time by performing image processing based on the image distortion sensing information and the environmental influence sensing information.
Functional blocks of the projector 20 for implementing such a function are described below.
FIG. 2 is a functional block diagram of the projector 20 according to the first embodiment.
The projector 20 includes an image distortion sensing section 180 which senses the image distortion sensing area 14 in a state in which the projection image 12 is projected onto the screen 10 to generate the image distortion sensing information, an environmental influence sensing section 182 which senses the environmental influence sensing area 15 in a state in which the projection image 12 is projected onto the screen 10 to generate the environmental influence sensing information, a storage section 160 which stores the sensing information, a processing section 100 which performs image processing based on the sensing information, and a projection section 190 which projects an image based on image information from the processing section 100. The image distortion sensing section 180 includes the image distortion sensor 60, and the environmental influence sensing section 182 includes the environmental influence sensor 62.
The processing section 100 includes a projection target area information generation section 101 which generates projection target area information indicating the position of the screen 10 in the sensing image of the image distortion sensing section 180, a projection area information generation section 102 which generates projection area information indicating the position of the projection image 12 in the sensing image, an image distortion correction section 103 which corrects distortion of the projection image 12 and generates correction information indicating the degree of correction, a display area information generation section 104 which generates display area information indicating the display area of the projection image 12 in the sensing image after distortion correction, and an environmental influence reduction section 105 which performs processing of reducing environmental influence caused by the difference between an ideal environment and an actual environment.
The processing section 100 includes an image information input section 110 which outputs image information (e.g. digital RGB signal) input from a PC or the like to the environmental influence reduction section 105 and includes the image distortion correction section 103, an image information output section 140 which outputs image information input from the environmental influence reduction section 105 to the projection section 190, a calibration information generation section 150 which generates calibration information for projecting the calibration projection image 12, and a differential image generation section 106 which generates a differential image based on the sensing information stored in the storage section 160.
The projector 20 has a zoom function for adjusting the size of the projection image 12. Therefore, the projection section 190 includes a zoom section 194 which adjusts the size of the projection image 12 in addition to a spatial light modulator 192 and a lens 196. The processing section 100 includes a control section 107 which controls the zoom section 194 and generates adjustment information indicating the degree of adjustment.
The environmental influence reduction section 105 includes a sensing information correction section 130 which generates corrected sensing information by determining a change in brightness of the projection image 12 due to adjustment based on the adjustment information from the control section 107, and correcting information inside the display area included in the environmental influence sensing information corresponding to the change in brightness, and an image information correction section 120 which corrects the image information based on the corrected sensing information so that the color and the brightness of the projection image 12 become ideal.
The image information correction section 120 includes a color correction section 122 which corrects the image information based on ideal color information indicating an ideal color and the corrected sensing information so that the projection image 12 is projected in the ideal color, and a brightness correction section 124 which corrects the image information corrected by the color correction section 122 based on ideal brightness information indicating ideal brightness and the corrected sensing information so that the projection image 12 is projected at the ideal brightness. Note that the brightness correction of the brightness correction section 124 includes grayscale correction which corrects the image information so that the projection image 12 is projected at an ideal grayscale in a state in which the projection image 12 is subjected to environmental influence.
As hardware for implementing the function of each section of the projector 20, the following hardware may be applied, for example.
FIG. 3 is a hardware block diagram of the projector 20 according to the first embodiment.
For example, the image information input section 110 may be implemented by using an A/D converter 930, an image processing circuit 970, or the like, the storage section 160 may be implemented by using a RAM 950 or the like, the projection target area information generation section 101, the projection area information generation section 102, and the differential image generation section 106 may be implemented by using the image processing circuit 970 or the like, the image distortion correction section 103, the display area information generation section 104, the control section 107, and the sensing information correction section 130 may be implemented by using a CPU910 or the like, the calibration information generation section 150 may be implemented by using the image processing circuit 970, the RAM 950, or the like, the image information output section 140 may be implemented by using a D/A converter 940 or the like, the spatial light modulator 192 may be implemented by using a liquid crystal panel 920 or the like, the color correction section 122 may be implemented by using a ROM 960 which stores the ideal color information, the RAM 950 which stores a color correction three-dimensional lookup table (3D-LUT), the image processing circuit 970 which corrects the 3D-LUT, or the like, and the brightness correction section 124 may be implemented by using the ROM 960 which stores the ideal brightness information, the RAM 950 which stores a brightness correction one-dimensional lookup table (1D-LUT), the image processing circuit 970 which corrects the 1D-LUT, or the like.
The image distortion sensing section 180 may be implemented by using an area sensor, a line sensor, or a phase difference sensor such as a CCD camera or a CMOS camera, for example. The image distortion sensing section 180 outputs an image signal value (e.g. RGB value, XYZ value, luminance value, or illuminance value) of each pixel in the sensing image as the image distortion sensing information, for example.
The environmental influence sensing section 182 may be implemented by using a silicon photodiode having a color filter or an RGB sensor and a shading cylinder optical system which places the sensing range within the environmental influence sensing area 15, for example. The environmental influence sensing section 182 outputs a brightness index value (e.g. voltage value, luminance value, or illuminance value) of each of R, G, and B through a color filter of each of R, G, and B as the environmental influence sensing information, for example.
These sections can exchange information through a system bus 980.
These sections may be implemented by hardware such as a circuit, or may be implemented by software such as a driver.
The function of the image distortion correction section 103 or the like may be implemented by a computer by causing the computer to read a program for causing the computer to function as the image distortion correction section 103 or the like from an information storage medium 900 which stores the program.
As the information storage medium 900, a CD-ROM, DVD-ROM, ROM, RAM, HDD, or the like may be applied. The program read method may be a contact method or a noncontact method.
The above-described functions may be implemented by downloading a program or the like for implementing the above-described functions from a host device or the like through a transmission line instead of reading the program from the information storage medium 900.
The image processing using the above-described sections is described below.
FIG. 4 is a flowchart showing the flow of image processing from preprocessing to generation of the projection target area information according to the first embodiment.
The projector 20 performs preprocessing (step S1). In more detail, when the user has activated the projector 20, the control section 107 controls the zoom section 194 so that the zoom state is set in an initial state. The calibration information generation section 150 generates position confirmation image calibration information, and the projection section 190 projects a position confirmation image based on the calibration information input through the environmental influence reduction section 105 and the image information output section 140. As the position confirmation image, an image having a center area formed by equally dividing the entire image into nine areas, a checkered pattern image described later, or the like may be used. The projector 20 allows the user to confirm whether or not the center area of the position confirmation image is projected onto the screen 10. When the center area of the position confirmation image is not projected onto the screen 10, the projector 20 allows the user to adjust the position of the projector 20 or the like so that the center area is reliably projected onto the screen 10.
When the user presses a correction button provided in the projector 20 after completion of the preprocessing, the projector 20 performs the distortion correction processing of the projection image 12 and the environmental influence reduction processing.
The calibration information generation section 150 generates calibration information for projecting a single-color image of which the entire image is green (G image). The projection section 190 projects the G image based on the calibration information.
The image distortion sensing section 180 senses the image distortion sensing area 14 at an automatic exposure in a state in which the G image is projected onto the screen 10 to generate first image distortion sensing information (step S2). The storage section 160 stores the first image distortion sensing information.
The environmental influence sensing section 182 senses the environmental influence sensing area 15 in a state in which the G image is projected onto the screen 10 to generate first environmental influence sensing information (step S3). The storage section 160 stores the first environmental influence sensing information.
The calibration information generation section 150 generates calibration information for projecting a multi-color image of which the entire image is in a checkered pattern made up of green and black (checkered pattern image).
FIG. 5 shows a checkered pattern image 16 according to the first embodiment.
The checkered pattern image 16 is equally divided into nine areas, in which the center image and four peripheral images at the four corners are black and the remaining four background images are green.
The projection section 190 projects the checkered pattern image 16 based on the calibration information for the checkered pattern image 16.
The image distortion sensing section 180 senses the image distortion sensing area 14 in a state in which the checkered pattern image 16 is projected onto the screen 10 at the exposure used when sensing the G image to generates second image distortion sensing information (step S4). The storage section 160 stores the second image distortion sensing information.
The calibration information generation section 150 generates calibration information for projecting a single-color image of which the entire image is red (R image). The projection section 190 projects the R image based on the calibration information.
The environmental influence sensing section 182 senses the environmental influence sensing area 15 in a state in which the R image is projected onto the screen 10 to generate second environmental influence sensing information (step S5). The storage section 160 stores the second environmental influence sensing information.
The calibration information generation section 150 generates calibration information for projecting a single-color image of which the entire image is blue (B image). The projection section 190 projects the B image based on the calibration information.
The environmental influence sensing section 182 senses the environmental influence sensing area 15 in a state in which the B image is projected onto the screen 10 to generate third environmental influence sensing information (step S6). The storage section 160 stores the third environmental influence sensing information.
The calibration information generation section 150 generates calibration information for projecting a single-color image of which the entire image is black (K image). The projection section 190 projects the K image based on the calibration information.
The image distortion sensing section 180 senses the image distortion sensing area 14 in a state in which the K image is projected onto the screen 10 at the exposure used when sensing the G image to generate third image distortion sensing information (step S7). The storage section 160 stores the third image distortion sensing information.
The environmental influence sensing section 182 senses the environmental influence sensing area 15 in a state in which the K image is projected onto the screen 10 to generate fourth environmental influence sensing information (step S8). The storage section 160 stores the fourth environmental influence sensing information.
The differential image generation section 106 generates a differential image (GK differential image) between the sensing image of the G image indicated by the first image distortion sensing information and the sensing image of the K image indicated by the third image distortion sensing information (step S9). The storage section 160 stores information on the GK differential image.
The differential image generation section 106 generates a differential image (checkered differential image) between the sensing image of the G image indicated by the first image distortion sensing information and the sensing image of the checkered pattern image 16 indicated by the second image distortion sensing information (step S10). The storage section 160 stores information on the checkered differential image.
The projection area information generation section 102 generates center area information indicating the position of the area of the center image (center area) in the sensing image of the image distortion sensing section 180 and peripheral area information indicating the positions of the areas of the peripheral images (peripheral areas) in the sensing image based on the information on the checkered differential image, and generates projection area information indicating the position of the projection image 12 (projection area) in the sensing image based on the center area information and the peripheral area information (step S11).
In more detail, the projection area information generation section 102 detects center reference positions of the center area and peripheral reference positions of the peripheral areas included in the checkered differential image by determining a point at which the value (differential value) of each pixel changes in the checkered differential image, for example. The projection area information generation section 102 determines the positions of the four corners of the center area based on the reference positions, and determines the positions of the four corners of the projection area based on the positions of the four corners of the center area. The projection area information corresponds to information indicating the positions of the four corners of the projection area in the sensing image, for example.
The projection target area information generation section 101 generates projection target area information indicating the position of the screen 10 in the sensing image based on the information on the GK differential image and the projection area information (step S12).
In more detail, the projection target area information generation section 101 generates the projection target area information by determining the boundary line by detecting the edge in the GK differential image from the positions of the four corners of the center area toward the outside based on the projection area information, for example. The projection target area information corresponds to information indicating the positions of the four corners of the screen 10 in the sensing image, for example.
FIG. 6 is a flowchart showing the flow of image processing from generation of correction information to image projection according to the first embodiment.
The image distortion correction section 103 generates correction information indicating the degree of correction of distortion of the projection image 12 based on the projection area information and the projection target area information (step S13).
In more detail, the image distortion correction section 103 determines the difference in shape between the projection area and the projection target area based on the projection area information and the projection target area information, and generates the correction information so that distortion of the projection image 12 is corrected according to the difference and the projection image 12 is displayed at a desired aspect ratio (height/width ratio).
As a more detailed processing procedure of the projection target area information generation section 101, the projection area information generation section 102, and the image distortion correction section 103, a method described in JP-A-2005-341139 may be used, for example. Therefore, description of the detailed processing procedure is omitted.
The display area information generation section 104 generates display area information indicating the display area of the projection image 12 in the sensing image after distortion correction based on the correction information and the projection area information (step S14).
The control section 107 determines the optimum zoom state after distortion correction based on the display area information, and controls the zoom section 194 so that the optimum zoom state is obtained (step S15).
The sensing information correction section 130 generates corrected sensing information indicating the average value of each of the RGB values in the display area in the optimum zoom state based on the information indicating the initial zoom state and the information indicating the optimum zoom state from the control section 107 and the first to fourth sensing information (step S16).
The color correction section 122 generates a 3D-LUT based on ideal color information indicating an ideal color and the corrected sensing information so that the projection image 12 is projected in the ideal color (step S17).
The brightness correction section 124 generates corrected sensing information of a white image (W image) by calculating the sum of the corrected sensing information of the R image, the corrected sensing information of the G image, and the corrected sensing information of the B image (step S18). In more detail, the brightness correction section 124 generates a value obtained by subtracting the corrected sensing information of the K image twice from the sum of the corrected sensing information of the R image, the corrected sensing information of the G image, and the corrected sensing information of the B image as the corrected sensing information of the W image. The corrected sensing information of the K image is subtracted twice in order to remove the external light component twice from the external light component trebled by the addition of three values.
The brightness correction section 124 generates a 1D-LUT based on the corrected sensing information from the sensing information correction section 130, the corrected sensing information of the W image, and ideal brightness information indicating ideal brightness so that the projection image 12 is projected at the ideal brightness (step S19).
The above-described procedure allows the projector 20 to be in a state in which the preparation for correcting the image information has been completed.
When the image information has been input from the PC, the image distortion correction section 103 corrects the image information based on the correction information in order to correct distortion of the projection image 12 (step S20).
The color correction section 122 corrects the image information corrected by the image distortion correction section 103 by using the 3D-LUT in order to correct the color of the projection image 12 (step S21).
The brightness correction section 124 corrects the image information corrected by the color correction section 122 by using the 1D-LUT in order to correct the brightness of the projection image 12 (step S22).
The image information output section 140 outputs the image information subjected to the image distortion correction processing and the environmental influence reduction processing to the projection section 190. The projection section 190 projects an image based on the image information (step S23).
As described above, according to the first embodiment, the projector 20 can more appropriately perform the environmental influence reduction processing when performing the distortion correction processing of the projection image 12 by performing the environmental influence reduction processing using the sensing information inside the display area after distortion correction.
Moreover, the projector 20 can more appropriately perform the environmental influence reduction processing when adjusting the size of the projection image 12 by performing the environmental influence reduction processing using the sensing information inside the display area after size adjustment by the zoom section 194.
According to the first embodiment, the projector 20 can efficiently perform the image processing by projecting and sensing five types of calibration images including the calibration images for correcting image distortion and the calibration images for correcting the color and the brightness. Specifically, according to the first embodiment, the projector 20 can correct image distortion and correct the color and the brightness taking into consideration the influence of the external light 80 and the color of the screen 10 almost at the same time. This allows the projector 20 to reduce the time required for the calibration processing to provide the user with a high degree of convenience.
According to the first embodiment, the projector 20 can sense an image in a state in which the center image of the checkered pattern image 16 is reliably included in the environmental influence sensing information by using the position confirmation image and allowing the user to confirm whether or not the area corresponding to the center image is positioned inside the screen 10. Therefore, the projector 20 can perform image processing by using appropriate sensing information.
According to the first embodiment, the projector 20 can generate the first image distortion sensing information at an environment-compliant exposure by initially sensing the G image having the highest luminance value at an automatic exposure setting. The projector 20 can generate the second and third image distortion sensing information at an exposure suitable for generation of the differential image by generating the second and third image distortion sensing information at the exposure used when sensing the G image.
According to the first embodiment, a sensor having minimum functions necessary for the objective can be used by providing the image distortion sensing section 180 and the environmental influence sensing section 182.
According to the first embodiment, since the projector 20 can always use the environmental influence sensing information inside the display area after image distortion correction by using an optical system which places the sensing range of the environmental influence sensing section 182 within the environmental influence sensing area 15, the projector 20 can appropriately perform the environmental influence reduction processing even when performing the image distortion correction processing.
Second Embodiment
When using a line sensor, a phase difference sensor, or the like as the image distortion sensing section 180, or when causing the image distortion correction section 103 to detect the peak position of the brightness index value (e.g. luminance value or illuminance value) included in the image distortion sensing information and correct distortion of the projection image 12 based on the peak position, the projector 20 need not use the projection target area information and the projection area information. When the zoom section 194 is not controlled by using the control section 107, the projector 20 need not use the display area information.
A second embodiment, in which the projector 20 performs the environmental influence reduction processing and the image distortion correction processing without using the projection target area information, the projection area information, and the display area information, is described below.
FIG. 7 is a flowchart showing the flow of image processing from generation of correction information to image projection according to the second embodiment.
The projector 20 according to the second embodiment does not include the projection target area information generation section 101, the projection area information generation section 102, the display area information generation section 104, the differential image generation section 106, the control section 107, the sensing information correction section 130, and the zoom section 194 shown in FIG. 2.
In the second embodiment, the environmental influence sensing section 182 includes a silicon photodiode having a color filter and a shading cylinder optical system for sensing a specific area of the projection image 12 always included in the image after image distortion correction as the environmental influence sensing area 15. In the second embodiment, a line sensor is used as the image distortion sensing section 180, for example.
The image distortion correction section 103 generates the correction information indicating the degree of correction of distortion of the projection image 12 based on the image distortion sensing information (step S31).
In more detail, the image distortion correction section 103 determines distortion of the projection image 12 based on the above-described peak position, and generates the correction information so that distortion of the projection image 12 is corrected according to the determination result and the projection image 12 is displayed at a desired aspect ratio (height/width ratio).
The color correction section 122 generates the 3D-LUT based on the ideal color information indicating the ideal color and the first to fourth environmental influence sensing information so that the projection image 12 is projected in the ideal color (step S32).
The brightness correction section 124 generates the environmental influence sensing information of the white image (W image) based on the first to third environmental influence sensing information (step S33). A specific method is the same as the method in the step S18.
The brightness correction section 124 generates the 1D-LUT based on the first to fourth environmental influence sensing information, the environmental influence sensing information of the W image, and the ideal brightness information indicating the ideal brightness so that the projection image 12 is projected at the ideal brightness (step S34).
The processing after the step S20 is the same as the processing according to the first embodiment. Therefore, further description is omitted.
As described above, the projector 20 can perform the environmental influence reduction processing and the image distortion correction processing without using the projection target area information, the projection area information, and the display area information.
According to the second embodiment, since the projector 20 does not require the projection target area information, image distortion can be corrected even when the projector 20 cannot detect the four corners of the screen 10 or the like.
The projector 20 may also perform zoom control in the second embodiment.
In this case, since the environmental influence sensing section 182 can sense the specific area of the projection image 12 always included in the image after image distortion correction irrespective of the zoom control state, the projector 20 can accurately determine the environmental influence in the specific area, so that the environmental influence reduction processing can be more appropriately performed when performing the distortion correction processing of the projection image 12.
Modification
The preferred embodiments to which the invention is applied are described above. However, the application of the invention is not limited to the above-described embodiments.
In the above-described embodiments, the projector 20 uses the checkered pattern image 16 made up of green and black. However, the projector 20 may use a checkered pattern image made up of a single-color other than green (red or blue) and black, for example. The color pattern of the checkered pattern image 16 may be the reverse of that described in above-described embodiments.
In the above-described embodiments, the projector 20 does not use a solid white image. However, the projector 20 may use a solid white image in addition to the above-described single-color images, and may use a checkered pattern image made up of white and black instead of the checkered pattern image 16.
In this case, the projector 20 must additionally perform processing of projecting and sensing a solid white image. However, the processing of generating the white corrected sensing information can be omitted.
An external light influence removal section may be provided in the processing section 100, for example. When a pixel area having a luminance value equal to or greater than a specific value exists in the image distortion sensing information of the K image, the external light influence removal section may replace the luminance value of that pixel area in the GK differential image with the luminance value of the pixel area near the pixel area in the GK differential image, and store the information after replacement in the storage section 160 as the image distortion sensing information of the K image.
This enables the projector 20 to perform appropriate image processing by removing partial influence of the external light 80.
The preprocessing (step S1) shown in FIG. 4 is not indispensable. The projector 20 may perform the processing after the step S2 immediately after startup.
When the projection section 190 does not have a zoom function, the image information correction section 120 may generate the 3D-LUT and the 1D-LUT by using the environmental influence sensing information inside the display area instead of using the corrected sensing information.
In the above-described embodiments, the sensor 60 projects and senses the K image. As a modification, the sensor 60 may generate the sensing information by sensing the screen 10 onto which an image is not projected.
The positional relationship between the projected image 12 and the screen 10 is not limited to the example shown in FIG. 1. For example, the entire outer frame of the projection image 12 may be positioned either outside or inside of the outer frame of the screen 10.
The checkered pattern image 16 is not limited to the image discussed in the above-described embodiments. For example, the shape of the center area or the peripheral area is not limited to quadrilateral, but may be circular, triangular, or the like.
The invention is also effective when projecting an image onto a projection target area other than the screen 10, such as a blackboard or a whiteboard.
The above-described embodiments illustrate an example in which the image processing system is provided in the projector 20. However, the image processing system may be provided in an image display system other than the projector 20, such as a cathode ray tube (CRT). As the projector 20, a projector using a digital micromirror device (MD) or the like may be used instead of a liquid crystal projector. DMD is a trademark of Texas Instruments, Inc. (U.S.A.).
The above-described functions of the projector 20 may be implemented by only the projector, or may be distributed over a plurality of processing devices (e.g. distribution processing by projector and PC).
In the above-described embodiments, the image distortion image distortion sensor 60 and the environmental influence sensor 62 are included in the projector 20. However, the image distortion image distortion sensor 60 and the environmental influence sensor 62 may be configured as devices independent of the projector 20.
Although only some embodiments of the invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the embodiments without departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention.

## Claims

1. An image processing system, comprising:
an image distortion sensing section which senses an area including at least a part of a projection image projected onto a projection target area to generate image distortion sensing information;
an environmental influence sensing section which senses a specific area of the projection image to generate environmental influence sensing information indicating a brightness index value in the specific area;
an image distortion correction section which corrects distortion of the projection image;
an environmental influence reduction section which performs processing of reducing environmental influence caused by a difference between an ideal environment and an actual environment; and
a projection section which projects a single-color red image, a single-color green image, a single-color blue image, and a solid black image as the projection image at different times;
the environmental influence sensing section sensing an area of the projection image always included in an image after image distortion correction as the specific area to generate the environmental influence sensing information of each of the single-color red image, the single-color green image, the single-color blue image, and the solid black image; and
the environmental influence reduction section performing the processing of reducing the environmental influence based on the environmental influence sensing information.

2. An image processing system, comprising:
an image distortion sensing section which senses an area including at least a part of a projection image projected onto a projection target area to generate image distortion sensing information;
an environmental influence sensing section which senses a specific area of the projection image near a center of the projection image to generate environmental influence sensing information indicating a brightness index value in the specific area;
a projection area information generation section which generates projection area information indicating a position of the projection image in a sensing image of the image distortion sensing section based on the image distortion sensing information;
an image distortion correction section which corrects distortion of the projection image and generates correction information indicating a degree of the correction;
a display area information generation section which generates display area information indicating a display area of the projection image in the sensing image after distortion correction based on the projection area information and the correction information;
an environmental influence reduction section which performs processing of reducing environmental influence caused by a difference between an ideal environment and an actual environment;
a projection section which projects a single-color red image, a single-color green image, a single-color blue image, a solid black image, and a multi-color image including one of red, green, and blue and black as the projection image at different times; and
a differential image generation section which generates a specific differential image;
the multi-color image including a center image positioned near a center of the multi-color image, a peripheral image positioned at periphery of the center image, and a background image other than the center and peripheral images, the center and peripheral images being black and the background image being a single color other than black, or the center and peripheral images being a single color other than black and the background image being black;
the image distortion sensing section sensing an area including at least a part of the multi-color image and the single-color image of red, green, blue, or black to generate the image distortion sensing information of each of the images;
the environmental influence sensing section sensing the specific area of the single-color red image, the single-color green image, the single-color blue image, and the solid black image to generate the environmental influence sensing information of each of the images;
the differential image generation section generating a pattern differential image based on the image distortion sensing information of the multi-color image and the image distortion sensing information of one of the single-color images;
the projection area information generation section generating center area information indicating a position of the center image in the sensing image and peripheral area information indicating a position of the peripheral image in the sensing image based on the pattern differential image, and generating the projection area information based on the center area information and the peripheral area information; and
the environmental influence reduction section performing the processing of reducing the environmental influence based on the environmental influence sensing information and the display area information.

3. The image processing system as defined in claim 2, comprising:
a control section which controls a zoom section which adjusts a size of the projection image based on the display area information so that the projection image is projected in an area corresponding to the display area in the projection target area at an optimum size, and generates adjustment information indicating a degree of the adjustment,
wherein the environmental influence reduction section includes:
a sensing information correction section which generates corrected sensing information by determining a change in brightness of the projection image due to the adjustment based on the adjustment information, and correcting information inside the display area included in the environmental influence sensing information corresponding to the change in brightness; and
an image information correction section which corrects image information based on the corrected sensing information so that a color and brightness of the projection image become ideal.

4. The image processing system as defined in claim 3,
wherein the image information correction section includes:
a color correction section which corrects the image information based on ideal color information indicating an ideal color and the corrected sensing information so that the projection image is projected in the ideal color; and
a brightness correction section which corrects the image information corrected by the color correction section based on ideal brightness information indicating ideal brightness and the corrected sensing information so that the projection image is projected at the ideal brightness.

5. The image processing system as defined in claim 4,
wherein the brightness correction section generates corrected sensing information of a solid white image based on the corrected sensing information of the single-color red image, the single-color green image, the single-color blue image, and the single-color black image, and corrects the image information corrected by the color correction section by utilizing the corrected sensing information of the solid white image.

6. The image processing system as defined in claim 1,
wherein the environmental influence correction section includes an image information correction section; and
wherein the image information correction section includes:
a color correction section which corrects the image information based on ideal color information indicating an ideal color and the environmental influence sensing information so that the projection image is projected in the ideal color; and
a brightness correction section which corrects the image information corrected by the color correction section based on ideal brightness information indicating ideal brightness and the environmental influence sensing information so that the projection image is projected at the ideal brightness.

7. The image processing system as defined in claim 6,
wherein the brightness correction section generates environmental influence sensing information of a solid white image based on the environmental influence sensing information of the single-color red image, the single-color green image, the single-color blue image, and the single-color black image, and corrects the image information corrected by the color correction section by utilizing the environmental influence sensing information of the solid white image.

8. The image processing system as defined in claim 2, comprising:
a projection target area information generation section which generates projection target area information indicating a position of the projection target area in the sensing image,
wherein the image distortion sensing section senses an area including at least a part of the solid black image to generate image distortion sensing information of the solid black image;
wherein the differential image generation section generates a brightness differential image based on the image distortion sensing information of the solid black image and the image distortion sensing information of one of the single-color images;
wherein the projection target area information generation section generates the projection target area information based on the brightness differential image and the projection area information; and
wherein the image distortion correction section corrects distortion of the projection image based on the projection target area information and the projection area information.

9. The image processing system as defined in claim 1,
wherein the projection section projects a position confirmation image for allowing a user to confirm whether or not the area corresponding to the specific area is projected into the projection target area before projecting the projection image.

10. A projector comprising the image processing system as defined in claim 1.

11. A projector comprising the image processing system as defined in claim 2.

12. An image processing method utilizing a computer including an image distortion sensing section, an environmental influence sensing section, a processing section, and a projection section, the method comprising:
causing the projection section to project a single-color red image, a single-color green image, a single-color blue image, a solid black image, and a multi-color image including one of red, green, and blue and black as the projection image at different times, the multi-color image including a center image positioned near a center of the multi-color image, a peripheral image positioned at periphery of the center image, and a background image other than the center image and the peripheral image;
causing the image distortion sensing section to sense an area including at least a part of the single-color red image, the single-color green image, the single-color blue image, or the solid black image projected onto a projection target area to generate first image distortion sensing information, to sense an area including at least a part of the multi-color image projected onto the projection target area to generate second image distortion sensing information;
causing the environmental influence sensing section to sense a specific area near the center of the single-color green image projected onto the projection target area to generate first environmental influence sensing information, to sense the specific area of the single-color red image projected onto the projection target area to generate second environmental influence sensing information, to sense the specific area of the single-color blue image projected onto the projection target area to generate third environmental influence sensing information, and to sense the specific area of the solid black image projected onto the projection target area to generate fourth environmental influence sensing information; and
causing the processing section to generate a pattern differential image based on the first and second image distortion sensing information, to generate center area information indicating a position of the center image in the sensing image of the image distortion sensing section and peripheral area information indicating a position of the peripheral image in the sensing image based on the pattern differential image, to generate projection area information indicating a position of the projection image in the sensing image based on the center area information and the peripheral area information, to generate correction information indicating a degree of correction of distortion of the projection image based on the projection area information, to generate display area information indicating a display area of the projection image in the sensing image after distortion correction based on the projection area information and the correction information, to correct image information based on the correction information so that image distortion is corrected, and to correct the image information based on the first to fourth environmental influence sensing information and the display area information so that environmental influence caused by a difference between an ideal environment and an actual environment is reduced.