Patent ID: 7737936

Claim:
A method of illuminating a backlit display, said method comprising: (a) spatially varying the luminance of a light source illuminating a plurality of displayed pixels, and based on a non-linear function of the spatial variance of luminance information from an input image to be displayed on said plurality of displayed pixels; (b) varying the transmittance of a light valve of said display in a non-binary manner; (c) temporally varying the spatial variance of said light source over a plurality of frames of a video stream; wherein (d) the step of varying in a luminance of a light source illuminating a displayed pixel comprises the steps of: (i) determining a luminance of said pixel from an intensity value of said pixel; and (ii) varying a luminance of said light source according to a relationship of said luminance of said pixel and said luminance of said light source by operating said light source at substantially a maximum luminance if a luminance of at least one displayed pixel exceeds a threshold luminance and otherwise, attenuating said luminance of said light source according to a relationship of said luminance of said light source and a luminance of a plurality of pixels.