Method, apparatus, and system providing an imager with pixels having extended dynamic range

摘要

The dynamic range of a pixel is increased by using selective photosensor resets during a frame time of image capture at a timing depending on the light intensity that the pixel will be exposed to during the frame time. Pixels that will be exposed to high light intensity are reset later in the frame than pixels that will be exposed to lower light intensity.

主权项

1. A method of operating an imager array containing a plurality of pixels, each having an associated photosensor, the method comprising:
determining for each of the pixels of the array an associated light intensity that the pixel photosensor will be exposed to during an image capture period; assigning to each pixel one of a plurality of brightness values, each brightness value being associated with a different pixel photosensor reset timing; and accumulating in the photosensor of each pixel a light intensity value during the image capture period and using a photosensor reset timing associated with an assigned pixel brightness value of each pixel to reset the accumulated light intensity value of the photosensor of each pixel during the image capture period, wherein each pixel comprises a floating diffusion region for receiving charge from a photosensor through a transfer transistor, a reset transistor for resetting charge on the floating diffusion region and a photosensor reset transistor for controlling operation of the transfer transistor, the method further comprising operating the reset transistor with reset control signals to reset the floating diffusion region a plurality of times during the image capture period and operating the photosensor reset transistor to control operation of the transfer transistor such that the photosensor is reset during the image capture period by connection to the floating diffusion region at a time corresponding to a reset of the floating diffusion region by the reset transistor.