Patent ID: 7714830

Claim:
A method of illuminating a backlit display, said method comprising the steps of: (a) spatially varying the luminance of a light source by (i) illuminating a plurality of displayed pixels in response to a plurality of pixel values dependent on the content of an image to be displayed on said display, (ii) modifying the illumination from said display based upon a filter that is determined at least in part by a non-uniform illumination profile of said light source, and; (iii) varying the transmittance of respective light valves arrayed over a viewing region of said display in a non-binary manner, wherein said light source is spatially displaced at a location at least partially directly beneath said plurality of pixels, wherein said light source provides different respective non-zero luminance intensities to first and second said light valves, relative to each other, using a non-linear transformation of said plurality of pixel values; (b) modifying the light to be output from said display by rescaling said light to be said output from said display in such a manner to alter the tone-scale of said light to be said output from said display from a state that would have substantially non-uniform tone-scale to a state that has substantially uniform tone-scale resulting from the luminance of said light source.