Patent ID: 7336309

Claim:
A method for compressing the dynamic range of an image sensor comprising a multiplicity of pixels, the method comprising the steps of: exposing each of said pixels to light and producing an associated photocurrent per pixel, representative of said light exposure; on a per-pixel basis, controlling exposure time of each of said pixels on the basis of a monotonically rising convex function of said associated photocurrent of each said pixel, wherein: controlling exposure time includes: calculating a photocurrent based on an accumulated voltage; and determining an exposure time, based on said monotonically rising convex function of said calculated photocurrent; and said monotonically rising convex function fulfills the following conditions: for I ph1 >I ph2 , f ( I ph1 )> f ( I ph2 ) and f ′( I ph1 )< f ′( I ph2 ), where f represents the monotonically rising convex function; f′ represents the first derivative of the function f; and I ph1 and I ph2 are arguments to function f and its first derivative f′.