Patent ID: 7973846

Claim:
A method in an image sensor for digitally recording an image of a scene within a snapshot of said scene, said image sensor comprising a two-dimensional array of pixel elements, said method comprising: after an initial exposure period within said snapshot, sampling pixel intensity values at said pixel elements at a plurality of sampling intervals within said snapshot, each of said pixel intensity values being indicative of a light intensity value impinging on each of said pixel elements in said array, wherein said snapshot is the total exposure time used by the image sensor to capture the image of the scene; providing an analog reference voltage corresponding to a digital count value which digital count value decrements from an initial count value to a final count value at said plurality of sampling intervals; comparing said pixel intensity values to said analog reference voltage at each of said plurality of sampling intervals; if said pixel intensity value of a first pixel element is less than said analog reference voltage at a first exposure time, generating an output signal having a first value at said first pixel element; in response to said output signal having said first value, recording said digital count value corresponding to said analog reference voltage at said first exposure time as pixel data associated with said first pixel element; and prior to said snapshot of said scene, setting a threshold indicator bit in a data memory of said image sensor associated with each of said pixel elements in said array to an initial value different than said first value, wherein said recording said digital count value comprises: if said threshold indicator bit associated with said first pixel element has a previous value different than said first value, storing in said data memory said output signal as said threshold indicator bit and storing said digital count value corresponding to said analog reference voltage at said first exposure time as pixel data associated with said first pixel element.