Patent ID: 7064740

Claim:
A method of illuminating a backlit display, said method comprising the step of spatially varying the luminance of a light source 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 and 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 varying the transmittance of a light valve 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 regions of said image that are sufficiently dark are attenuated by reducing the luminance of said light source, wherein regions of said image that are not said sufficiently dark are not attenuated in the same manner as said sufficiently dark regions by reducing the luminance of said light source, wherein different regions of said light source provide different non-zero luminance, modifying the light to be output from said display by rescaling said output from said display in such a manner to alter the tone-scale of 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.