Method for capturing and storing image information for multiple sampling operations in a digital pixel sensor
First Claim
1. An image sensor, comprising:
- a sensor array comprising a two-dimensional array of pixel elements, said sensor array outputting digital signals as pixel data representing an image of a scene, and said sensor array generating multiple representations of said image at a plurality of exposure times; and
a data memory, in communication with said sensor array, for storing image information for each of said pixel elements, said data memory allocating for each pixel element an m-bit pixel data field for storing pixel data generated by said sensor array and an n-bit CDS data field for storing reset value associated with each pixel element;
wherein said data memory uses a first bit of said pixel data field as a threshold indicator indicating whether pixel data associated with each pixel element has exceeded a predetermined threshold level, said data memory storing m+n bits of pixel data in said pixel data field and said CDS data field for pixel data exceeding said predetermined threshold level and storing m bits of pixel data in said pixel data field for pixel data not exceeding said predetermined threshold level.
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Abstract
A method for storing image information in a digital pixel sensor is disclosed for reducing the size of the memory needed to facilitate multiple sampling and correlated double sampling. In one embodiment, an image sensor includes a sensor array of pixel elements generating digital pixel data and a data memory for storing pixel data of each pixel element. The data memory allocates for each pixel element an m-bit pixel data field for storing pixel data and an n-bit CDS data field for storing reset value associated with each pixel element. The data memory stores m+n bits of pixel data in the pixel data field and the CDS data field for pixel data exceeding the predetermined threshold level. The data memory stores m bits of pixel data in the pixel data field for pixel data not exceeding the predetermined threshold level.
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Citations
20 Claims
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1. An image sensor, comprising:
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a sensor array comprising a two-dimensional array of pixel elements, said sensor array outputting digital signals as pixel data representing an image of a scene, and said sensor array generating multiple representations of said image at a plurality of exposure times; and a data memory, in communication with said sensor array, for storing image information for each of said pixel elements, said data memory allocating for each pixel element an m-bit pixel data field for storing pixel data generated by said sensor array and an n-bit CDS data field for storing reset value associated with each pixel element; wherein said data memory uses a first bit of said pixel data field as a threshold indicator indicating whether pixel data associated with each pixel element has exceeded a predetermined threshold level, said data memory storing m+n bits of pixel data in said pixel data field and said CDS data field for pixel data exceeding said predetermined threshold level and storing m bits of pixel data in said pixel data field for pixel data not exceeding said predetermined threshold level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for generating electrical signals representing an image in a digital image sensor, comprising:
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resetting said digital image sensor; generating digital signals as reset values associated with each pixel element, said reset values being indicative of a pixel intensity value at each of said pixel elements after said resetting; storing said reset values in a data memory, said reset values being stored in an n-bit CDS data field associated with each pixel element; generating digital signals as pixel data at a plurality of exposure times, said pixel data being associated with each pixel element in a sensor array of pixel elements and corresponding to a level of an analog signal indicative of a light intensity impinging on said pixel element; determining if said pixel data of a first pixel element exceeds a predetermined threshold value; if said pixel data exceeds said predetermined threshold value, storing m+n bits of pixel data in an m-bit pixel data field and said n-bit CDS data field in said data memory; and if said pixel data does not exceed said predetermined threshold value, storing m bits of pixel data in said pixel data field of said data memory. - View Dependent Claims (12, 13, 14, 15)
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16. An image sensor, comprising:
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a sensor array comprising a two-dimensional array of pixel elements, said sensor array outputting digital signals as pixel data representing an image of a scene, and said sensor array generating multiple representations of said image at k numbers of exposure times; and a data memory, in communication with said sensor array, for storing image information for each of said pixel elements, said data memory allocating for each pixel element r bits of memory locations for storing pixel data generated by said sensor array and for storing reset value associated with each pixel element; wherein said data memory uses a first bit of said pixel data field as a threshold indicator indicating whether pixel data associated with each pixel element has exceeded a predetermined threshold level, said data memory storing zero to n-1 bits of reset values for pixel data exceeding said predetermined threshold level at the first to the (k-1)th exposure times, and said data memory storing n bits of rest values for pixel data captured at the (k)th exposure times. - View Dependent Claims (17, 18, 19, 20)
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Specification