Integrated sensor with frame memory and programmable resolution for light adaptive imaging
AssigneeCalifornia Institute of Technology
InventorsZhimin Zhou, Eric R. Fossum, Bedabrata Pain
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Abstract
An image sensor operable to vary the output spatial resolution according to a received light level while maintaining a desired signal-to-noise ratio. Signals from neighboring pixels in a pixel patch with an adjustable size are added to increase both the image brightness and signal-to-noise ratio. One embodiment comprises a sensor array for receiving input signals, a frame memory array for temporarily storing a full frame, and an array of self-calibration column integrators for uniform column-parallel signal summation. The column integrators are capable of substantially canceling fixed pattern noise.
Claims20
An image sensor for imaging an object, comprising:
- a light sensing array configured to receive an input image of said object, said light sensing array having a plurality of detector pixels, said detector pixels arranged with respect to one another to form a plurality of columns and a plurality of rows;
- a frame memory array formed on a substrate with said light sensing array and configured to store radiation-induced signals produced by said light sensing array indicative of said input image, said frame memory array having a plurality of memory cells, each said memory cell corresponding to one of said detector pixels;
- a signal processor formed on said substrate with said frame memory and configured to process signals from said frame memory array to produce an output image with a prespecified signal magnitude and signal-to-noise ratio;
- and
- a control circuit arranged and configured to control said light sensing array, said frame memory array and said signal processor.
An integrated sensor with a programmable resolution, comprising:
- a light sensing array having a plurality of sensing pixels that are arranged with respect to one another to form a plurality of columns and a plurality of rows, said light sensing array having a sensor row decoder addressing and selecting at least one row of said sensing pixels;
- a frame memory array for storing radiation-induced signals that are produced by said light sensing array, said frame memory array having a plurality of memory cells each corresponding to one of said sensing pixels and a memory row detector for addressing and selecting at least one row of said memory cells;
- a column integrator array having a plurality of integrating circuits each connected to one of said columns in said frame memory;
- a column memory array having column memory cells for receiving signals from said integrating circuits;
- a column selector configured to select at least one column of said frame memory cells;
- an output integrator configured to integrate column signals from said column integrator array that are selected by said column selector;
- and
- a control circuit configured to control said light sensing array, said frame memory array, said column integrator, said column selector, and said output integrator to produce an output image satisfying a signal magnitude criterion and a signal-to-noise ratio criterion based on an adjustment of the resolution of said output image.
A method for performing light adaptive imaging with an image sensor having a sensor array of sensing pixels arranged in columns and rows, comprising:
- capturing a first frame indicative of an image of an object sensed by said sensing pixels;
- saving said first frame in a frame memory;
- comparing signal magnitudes of said sensed pixels in said first frame with a predetermined threshold value;
- determining a first number of sensing pixels in a first summation kernel consisting of neighboring pixels according to a result of said comparing;
- capturing a second frame indicative of an image of said object;
- saving said second frame in said frame memory;
- dividing said sensor array into a plurality of components with each component being said summation kernel with said first number of sensing pixels;
- and
- adding signals of said sensing pixels in said summation kernel to generate a resolution-reduced array of signals indicative of said second frame with an improved signal-to-noise ratio and an increased signal magnitude.
Dependencies are inferred from the claim text.