Patent ID: 7256841

Claim:
A projection display apparatus for projecting an image onto a screen, comprising: a light source; a signal processing unit for processing an input image signal to output a first image signal representing first primary-color information R 1 , G 1 , and B 1 representing values of red, green, and blue components of an image to be projected; a signal conversion unit for converting the first image signal into a second image signal representing a coefficient M which depends on luminance of the image to be projected defined by the first primary-color information R 1 , G 1 , and B 1 , and into a third image signal representing second primary-color information R 2 =R 1 /M, G 2 =G 1 /M, and B 2 =B 1 /M; a first light valve for modulating light received from the light source in accordance with the coefficient M, the light changing in color among red, green, and blue in sequence; a second light valve for further modulating the light received from the first light valve in accordance with the second primary-color information R 2 , G 2 , and B 2 in sequence; and a projection unit for throwing the light received from the second light valve onto the screen.