Wide dynamic range cmos image sensor

Abstract

An image sensor with a pixel array that includes at least one pixel. The sensor may also include a circuit that is connected to the pixel and provides a final image pixel value that is a function of a sampled reset output signal generated from the pixel. The final image pixel value is set to a reserved value if the sampled reset output signal exceeds a threshold. The final image may be a function of first, second and/or third images and a field that provides information on whether the final image includes a first exposure rate, a second exposure rate and/or a third exposure rate.

1 . A method for generating an extended dynamic range image from a pixel array of an image sensor, comprising:
 generating a first sequence of more than two image pixel values sequentially from a photodiode, each one having a different exposure; and,   forming a second sequence of more than two combined image pixel values,   wherein, except an earliest one in the second sequence, each combined image pixel value of the second sequence results from a selection between an immediate prior combined image pixel value of the second sequence and an image pixel value of the first sequence and is assigned a source label that indicates which is selected.   
     
     
         2 . The method of  claim 1 , wherein each of the earliest to the penultimate image pixel values of the first sequence has an exposure duration more than one line period. 
     
     
         3 . The method of  claim 1 , wherein the first sequence is ordered from longer to shorter exposures. 
     
     
         4 . The method of  claim 1 , wherein the immediate prior combined image pixel value is selected if the image pixel value exceeds a threshold. 
     
     
         5 . (canceled) 
     
     
         6 . The method  claim 1 , wherein each of the second to the penultimate combined image pixel values of the second sequence is stored to and retrieved from memory, overwriting an earlier combined image pixel value that has been stored and retrieved for the photodiode or another photodiode. 
     
     
         7 . The method  claim 2 , wherein each of the second to the penultimate combined image pixel values of the second sequence is stored to and retrieved from memory, overwriting an earlier combined image pixel value that has been stored and retrieved for the photodiode or another photodiode. 
     
     
         8 . The method  claim 3 , wherein each of the second to the penultimate combined image pixel values of the second sequence is stored to and retrieved from memory, overwriting an earlier combined image pixel value that has been stored and retrieved for the photodiode or another photodiode. 
     
     
         9 . The method  claim 4 , wherein each of the second to the penultimate combined image pixel values of the second sequence is stored to and retrieved from memory, overwriting an earlier combined image pixel value that has been stored and retrieved for the photodiode or another photodiode.