Luminance correcting apparatus, luminance correcting method, and projector

1. A luminance correcting apparatus for correcting the luminance of an image projected onto a screen by a projecting apparatus based on the luminance of reflected light from image light projected onto the screen by the projecting apparatus, comprising:

detecting means for detecting luminance of reflected lights of projected lights individually in red, green, blue and one other color having a center wavelength that is different from a center wavelength of red, green and blue;

first memory means for storing information representing luminances of the reflected lights in the respective colors which are detected by said detecting means;

second memory means for storing information representing predetermined reference luminances of the reflected lights in the respective colors;

luminance correcting data generating means for generating luminance correcting data by comparing the information stored in said first memory means and the information stored in said second memory means; and

correcting means for correcting an image signal input to said projecting apparatus based on said luminance correcting data to increase color reproducibility.

2. A luminance correcting apparatus according to claim 1 , wherein the information stored in said first memory means comprises information produced by subtracting the luminance of ambient light reflected from said screen with no image light projected onto said screen, from the luminances of the reflected lights in the respective colors which are detected by said detecting means.

3. A luminance correcting apparatus according to claim 1 , wherein the information stored in said second memory means comprises information representing the luminances of the reflected lights in the respective colors which are detected by said detecting means when image lights in at least the two colors are individually projected onto a white screen.

4. A projector having a projecting apparatus for projecting image lights in at least two colors produced by an image forming device onto a screen and a luminance correcting apparatus for correcting the luminance of an image projected onto the screen by the projecting apparatus based on the luminances of reflected lights from image lights projected onto the screen by the projecting apparatus, wherein said luminance correcting apparatus comprising:

detecting means for detecting luminances of reflected lights of projected lights individually in red, green, blue and one other color having a center wavelength that is different from a center wavelength of red, green and blue;

first memory means for storing information representing luminances of the reflected lights in the respective colors which are detected by said detecting means;

second memory means for storing information representing predetermined reference luminances of the reflected lights in the respective colors;

luminance correcting data generating means for generating luminance correcting data by comparing the information stored in said first memory means with the information stored in said second memory means; and

correcting means for correcting an image signal input to said projecting apparatus based on said luminance correcting data to increase color reproducibility.

5. A projector according to claim 4 , wherein the information stored in said first memory means comprises information produced by subtracting the luminance of ambient light reflected from said screen with no image light projected onto said screen, from the luminances of the reflected lights in the respective colors which are detected by said detecting means.

6. A projector according to claim 4 , wherein the information stored in said second memory means comprises information representing the luminances of the reflected lights in the respective colors which are detected by said detecting means when image lights in at least two colors are individually projected onto a white screen.

7. A method of correcting the luminance of an image projected onto a screen in a projector for displaying an image on the screen by projecting image lights in at least two colors produced by an image forming device, comprising the steps of

successively projecting the image lights in the at least two colors onto said screen, at least one of the at least two colors being a non-additive-primary color, the at least one non-additive primary color is defined by a color band that overlaps a color band of another of the at least two colors;

detecting a luminance of a reflected light individually in red, green, blue and one other color having a center wavelength that is different from a center wavelength of red, green and blue from an image light projected onto said screen each time an image light in a different color is projected onto said screen;

generating luminance correcting data by comparing detected luminances of reflected lights in respective colors with predetermined reference luminances for the respective colors; and

correcting an image signal input to said image forming device based on the generated luminance correcting data to increase color reproducibility.

8. A method of correcting the luminance of an image projected onto a screen in a projector that is used for displaying an image on the screen by projecting a mixed-color image light including image lights in at least two colors produced by an image forming device, comprising the steps of:

projecting the mixed-color image light onto said screen;

individually detecting luminance of reflected lights in red, green, blue and one other color having a center wavelength that is different from a center wavelength of red, green and blue included in reflected lights from said screen;

generating luminance correcting data by comparing the detected luminances in the respective colors with predetermined reference luminances for the respective colors; and

correcting an image signal input to said image forming device based on the generated luminance correcting data to increase color reproducibility.

9. A method according to claim 7 , further comprising the steps of:

detecting a luminance of reflected light from ambient light which is reflected from said screen with no image light projected onto the screen; and

subtracting the luminance of the reflected light, that is from said ambient light, from the luminances of the reflected lights of the image lights projected onto said screen, producing differential luminances;

wherein said luminance correcting data are generated by comparing the differential luminances with said reference luminances.

10. A method according to claim 8 , further comprising the steps of:

detecting a luminance of reflected light from ambient light which is reflected from said screen with no image light projected onto the screen; and

subtracting the luminance of the reflected light, that is from said ambient light, from the luminances of the reflected lights of the image lights projected onto said screen, producing differential luminances;

wherein said luminance correcting data are generated by comparing the differential luminances with said reference luminances.