Keystone correction using a part of edges of a screen

An image correction method for correcting an image projected onto a screen by a projector, the projector including an image forming panel for forming, in an image forming area of a panel surface, an effective panel image for modulating light that is emitted from the light source into an effective image light that represents an image, the method comprising the steps of:

• (a) generating a captured image by capturing at least a specific projection area wherein the image light, corresponding to a specific area within the image forming area, is projected;
• (b) calculating one or more edges of outside perimeter lines of the specific projection area and one or more edges of the screen, through analyzing the captured image and detecting plural points on the outside perimeter lines of the specific projection area and of the screen within the captured image;
• (c) calculating, based on detection results in the step (b), post-correction image forming area that is a part of the image forming area;
• and
• (d) correcting trapezoidal distortion of an image that is displayed on the screen through forming of the effective panel image in the post-correction image forming area within the image forming area,
• wherein the step (c) includes a step of calculating, when only three or less edges among four edges of the outside perimeter lines of the screen have been detected in the step (b), the post-correction image forming area based on a position and a slope of the detected edge within the captured image.

A computer program product for correcting an image that is projected on a screen by a projector, the projector including an image forming panel for forming, in an image forming area of a panel surface, an effective panel image for modulating light that is emitted from the light source into an effective image light that represents an image and an image capturing unit configured to generate a captured image by capturing at least a specific projection area wherein the image light, corresponding to a specific area within the image forming area, is projected, the computer program product comprising:

• a computer readable medium;
• and
• a computer program stored on the computer readable medium, the computer program comprising:
• a first program for calculating one or more edges of outside perimeter lines of the specific projection area and one or more edges of the screen, through analyzing the captured image and detecting plural points on the outside perimeter lines of the specific projection area and of the screen within the captured image;
• a second program for calculating, based on detection results by the first program, post-correction image forming area that is a part of the image forming area;
• and
• a third program for correcting trapezoidal distortion of an image that is displayed on the screen through forming of the effective panel image in the post-correction image forming area within the image forming area,
• wherein the second program includes a program for calculating the post-correction image forming area when only three or less edges among four edges of the outside perimeter lines of the screen have been calculated by the first program, the post-correction image forming area being calculated based on a position and a slope of the detected edge within the captured image.

A projector for displaying an image on a screen comprising:

• a light source for emitting light;
• an image forming panel for modulating light that is emitted from the light source into an image light that represents an image;
• an image capturing unit configured to generate a captured image by capturing at least a specific projection area wherein the image light is projected;
• an outside perimeter line detecting unit configured to calculate one or more edges of outside perimeter lines of the specific projection area and one or more edges of the screen, through analyzing the outside perimeter lines of the specific projection area and of the screen within the captured image;
• a post-correction image forming area calculating unit configured to calculate, based on detection results by the outside perimeter line detecting unit, post-correction image forming area;
• and
• a keystone correcting unit configured to correct trapezoidal distortion of an image that is displayed on the screen through forming of the in image the post-correction image forming area,
• wherein the post-correction image forming area calculating unit calculates the post-correction image forming area based on positions and slopes of one or more edges among edges of the outside perimeter lines of the screen detected by the outside perimeter line detecting unit.

An image correction method for correcting an image projected onto a screen by a projector, the projector including an image forming panel for modulating light that is emitted from the light source into an image light that represents an image, the method comprising the steps of:

• (a) generating a captured image by capturing at least a specific projection area wherein the image light is projected;
• (b) calculating one or more edges of outside perimeter lines of the specific projection area and one or more edges of the screen, through analyzing the outside perimeter lines of the specific projection area and of the screen within the captured image;
• (c) calculating, based on detection results in the step (b), post-correction image forming area;
• and
• (d) correcting trapezoidal distortion of an image that is displayed on the screen through forming of the image in the post-correction image forming area,
• wherein the step (c) includes a step of calculating the post-correction image forming area based on positions and slopes of one or more edges among edges of the outside perimeter lines of the screen detected by the step (b).

A computer program product for correcting an image that is projected on a screen by a projector, the projector including an image forming panel for modulating light that is emitted from the light source into an image light that represents an image and an image capturing unit configured to generate a captured image by capturing at least a specific projection area wherein the image light is projected, the computer program product comprising:

• a computer readable medium;
• and a computer program stored on the computer readable medium, the computer program comprising:
• a first program for calculating one or more edges of outside perimeter lines of the specific projection area and one or more edges of the screen, through analyzing the outside perimeter lines of the specific projection area and of the screen within the captured image;
• a second program for calculating, based on detection results by the first program, post-correction image forming area;
• and
• a third program for correcting trapezoidal distortion of an image that is displayed on the screen through forming of the image in the post-correction image forming area within the image forming area,
• wherein the second program includes a program for calculating the post-correction image forming area based on positions and slopes of one or more edges among edges of the outside perimeter lines of the screen detected by the first program.