Low-light-level imaging and image processing
First Claim
1. An imaging system for imaging a scene to produce a sequence of image frames of the scene at a frame rate, R, of at least about 25 image frames per second, the imaging system comprising:
- an optical input port for accepting input light from the scene;
a charge-coupled imaging device comprising an array of pixels configured in a charge storage medium, the charge-coupled imaging device located in relation to the input port such that input light from the scene impinges device pixels, the charge-coupled imaging device producing an electrical pixel signal of analog pixel values based on the input light;
an analog signal processor connected to the charge-coupled imaging device for amplifying the pixel signal;
an analog-to-digital processor connected to the analog signal processor for digitizing the amplified pixel signal to produce a digital image signal formatted as a sequence of image frames each of a plurality of digital pixel values and having a dynamic range of digital pixel values represented by a number of digital bits, B, where B is greater than 8; and
a digital image processor connected to the analog-to-digital processor for processing digital pixel values in the sequence of image frames to produce an output image frame sequence at the frame rate, R, representative of the imaged scene, with a latency of no more than about 1/R;
the output image frame sequence being characterized by noise-limited resolution of at least a minimum number, NM, of line pairs per millimeter, referred to the charge-coupled imaging device pixel array, in an imaged scene as a function of illuminance of the input light impinging the charge-coupled imaging device pixels, wherein for a scene characterized by a contrast of about 0.3, for a human observation time of about 0.05 seconds, and for an image scene frame rate of about 30 frames per second, NM is given as NM =1900 L0.51, where L is the value of illuminance of the input light impinging the charge-coupled imaging device pixels, for at least one illuminance value between a range of illuminance values of about 1×
10-2 LUX and 5×
10-7 LUX.
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0 Petitions
Accused Products
Abstract
An imaging system is provided for imaging a scene to produce a sequence of image frames of the scene at a frame rate, R, of at least about 25 image frames per second. The system includes an optical input port, a charge-coupled imaging device, an analog signal processor, and an analog-to-digital processor (A/D). The A/D digitizes the amplified pixel signal to produce a digital image signal formatted as a sequence of image frames each of a plurality of digital pixel values and having a dynamic range of digital pixel values represented by a number of digital bits, B, where B is greater than 8. A digital image processor is provided for processing digital pixel values in the sequence of image frames to produce an output image frame sequence at the frame rate, R, representative of the imaged scene, with a latency of no more than about 1/R and a dynamic range of image frame pixel values represented by a number of digital bits, D, where D is less than B. The output image frame sequence is characterized by noise-limited resolution of at least a minimum number, NM, of line pairs per millimeter, referred to the charge-coupled imaging device pixel array, in an imaged scene as a function of illuminance of the input light impinging the charge-coupled imaging device pixels.
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Citations
47 Claims
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1. An imaging system for imaging a scene to produce a sequence of image frames of the scene at a frame rate, R, of at least about 25 image frames per second, the imaging system comprising:
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an optical input port for accepting input light from the scene; a charge-coupled imaging device comprising an array of pixels configured in a charge storage medium, the charge-coupled imaging device located in relation to the input port such that input light from the scene impinges device pixels, the charge-coupled imaging device producing an electrical pixel signal of analog pixel values based on the input light; an analog signal processor connected to the charge-coupled imaging device for amplifying the pixel signal; an analog-to-digital processor connected to the analog signal processor for digitizing the amplified pixel signal to produce a digital image signal formatted as a sequence of image frames each of a plurality of digital pixel values and having a dynamic range of digital pixel values represented by a number of digital bits, B, where B is greater than 8; and a digital image processor connected to the analog-to-digital processor for processing digital pixel values in the sequence of image frames to produce an output image frame sequence at the frame rate, R, representative of the imaged scene, with a latency of no more than about 1/R; the output image frame sequence being characterized by noise-limited resolution of at least a minimum number, NM, of line pairs per millimeter, referred to the charge-coupled imaging device pixel array, in an imaged scene as a function of illuminance of the input light impinging the charge-coupled imaging device pixels, wherein for a scene characterized by a contrast of about 0.3, for a human observation time of about 0.05 seconds, and for an image scene frame rate of about 30 frames per second, NM is given as NM =1900 L0.51, where L is the value of illuminance of the input light impinging the charge-coupled imaging device pixels, for at least one illuminance value between a range of illuminance values of about 1×
10-2 LUX and 5×
10-7 LUX. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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20. A charge-coupled imaging device for imaging a scene to produce a sequence of image frames of the scene at an image frame rate, R, of at least about 25 image frames per second, the charge-coupled imaging device comprising:
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a charge storage medium comprising a substrate having a front side and a backside; an array of pixels defined in the charge storage substrate by pixel interconnections supported on the front side of the substrate, exposure of the substrate to light from the scene producing charge packets in the pixels, the pixel interconnections providing selective electronic temporal control of transfer of charge packets from one pixel to another in the substrate; means for suppressing generation of dark current charge packet generation in the substrate pixels; and an output circuit for converting the charge packets in the pixels to an electrical pixel signal of output pixel values based on the light from the scene, a plurality of pixel values together forming an image frame, the output circuit characterized by a capacitance of less than about 10 femtoFarads; the output pixel values being characterized by noise-limited resolution of at least a minimum number, NM, of line pairs per millimeter, referred to the charge-coupled imaging device pixel array, in an image frame configured of the output pixel values as a function of illuminance of the light from the scene impinging the charge-coupled imaging device pixels, wherein for a scene characterized by a contrast of about 0.3, for a human observation time of about 0.05 seconds, and for an image scene frame rate of about 30 frames per second, NM is given as NM =1900 L0.51, where L is the value of illuminance of the input light impinging the charge-coupled imaging device pixels, for at least one illuminance value between a range of illuminance values of about 1×
10-2 LUX and 1×
10-7 LUX. - View Dependent Claims (19, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. An imaging system for imaging a scene to produce a sequence of color image frames of the scene at a frame rate, R, of at least about 25 image frames per second, the imaging system comprising:
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an optical input port for accepting input light from the scene; a spectral range separator located in re lation t o the input port to receive the input light, the spectral range separator separating the input light into distinct spectral ranges; an imager system comprising at least one charge-coupled imager having an array of a plurality of pixels configured in a charge storage medium, the at least one charge-coupled imager being located in relation to the spectral range separator such that separated spectral ranges of input light impinge charge storage medium pixels, the at least one charge-coupled imager being characterized by monochromatic noise-limited resolution of at least a minimum number, NM, of line pairs per millimeter, referred to the imager pixel array, in an imaged scene as a function of illuminance of input light impinging the pixel array, wherein for a scene characterized by a contrast of about 0.3, for a human observation time of about 0.05 seconds, and for a monochromatic image scene frame rate of about 30 frames per second, NM is given as NM =1900 L0.51, where L is the value of illuminance of input light impinging the pixel array, for at least one illuminance value between a range of illuminance values of about 1×
10-2 LUX and 5×
10-7 LUX, the imager system producing a plurality of electrical pixel signals of analog pixel values based on the spectral ranges of input light that impinge the pixels, each electrical pixel signal corresponding to a distinct spectral range;an analog signal processor connected to receive each pixel signal for amplifying the pixel signals; an analog-to-digital processor connected to the analog signal processor for digitizing the amplified pixel signals to produce corresponding digital image signals having a dynamic range of digital pixel values represented by a number of digital bits, B, where B is greater than 8; and an image processor connected to receive the digital image signals and to combine together the digital image signals to produce a sequence of color image frames, each color image frame having pixel values based on the separated spectral ranges of input light, the sequence of color image frames being produced at the frame rate, R, with a latency of no more than about 1/R. - View Dependent Claims (35, 36, 37, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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38. The imaging system of claim 58 wherein the spectral range separator is adapted to separate the input light into a red spectral range of input light, a green spectral range of input light, and a blue spectral range of input light;
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wherein the imager system comprises a first charge-coupled imager designated for a red spectral range and located to receive at that imager'"'"'s pixels the separated red input light from the spectral range separator, a second charge-coupled imager designated for a green spectral range and located to receive at that imager'"'"'s pixels the separated green input light from the spectral range separator, and a third charge-coupled imager designated for a blue spectral range and located to receive at that imager'"'"'s pixels the separated blue input light from the spectral range separator.
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Specification