Fixed pattern noise subtraction in a digital image sensor
First Claim
1. A method for subtracting fixed pattern noise in a digital imaging system incorporating a digital image sensor, comprising:
- acquiring a reference image of the digital image sensor when the digital image sensor receives no illumination;
storing a reference value of an operating parameter associated with the reference image, wherein the reference image is indicative of the fixed pattern noise associated with the digital image sensor when the operating parameter has the reference value;
storing a model describing the behavior of the fixed pattern noise as a function of the operating parameter;
acquiring a first image;
measuring a current value of the operating parameter associated with the first image;
calculating a noise prediction image by extrapolation of the reference image in accordance with the model and based on the current value and the reference value of the operating parameter; and
subtracting the noise prediction image from the first image to generate a final image.
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Abstract
A fixed pattern noise subtraction method in a digital imaging system incorporating a digital image sensor includes: acquiring a reference image of the digital image sensor when the digital image sensor receives no illumination, storing a reference value of an operating parameter associated with the reference image where the reference image is indicative of the fixed pattern noise associated with the digital image sensor, storing a model describing the behavior of the fixed pattern noise as a function of the operating parameter. Then, the method continues with acquiring a first image, measuring a current value of the operating parameter associated with the first image, calculating a noise prediction image by extrapolation of the reference image in accordance with the model and based on the current value and the reference value of the operating parameter, and subtracting the noise prediction image from the first image to generate a final image.
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Citations
20 Claims
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1. A method for subtracting fixed pattern noise in a digital imaging system incorporating a digital image sensor, comprising:
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acquiring a reference image of the digital image sensor when the digital image sensor receives no illumination; storing a reference value of an operating parameter associated with the reference image, wherein the reference image is indicative of the fixed pattern noise associated with the digital image sensor when the operating parameter has the reference value; storing a model describing the behavior of the fixed pattern noise as a function of the operating parameter; acquiring a first image; measuring a current value of the operating parameter associated with the first image; calculating a noise prediction image by extrapolation of the reference image in accordance with the model and based on the current value and the reference value of the operating parameter; and subtracting the noise prediction image from the first image to generate a final image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An imaging system, comprising:
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a digital image sensor for performing image capture operations, comprising; a sensor array comprising a two-dimensional array of digital pixels, each digital pixel outputting digital signals as pixel data representing an image of a scene; an image buffer, in communication with the sensor array, for storing the pixel data; and a first processor, in communication with the image buffer and the sensor array, for controlling image capture and pixel data processing operations; and a digital image processor for performing image processing operations, comprising; a frame buffer, in communication with the digital image sensor, coupled to store the pixel data, wherein the frame buffer includes a first bit field for storing the pixel data for a first image and a second bit field for storing noise data associated with the sensor array; a second processor, in communication with the frame buffer, for processing the pixel data stored in the frame buffer; and a memory buffer, in communication with the second processor, for storing a reference image of the sensor array and a reference value of an operating parameter, wherein the reference image is indicative of the fixed pattern noise associated with the digital image sensor when the operating parameter has the reference value, wherein when the digital image sensor captures a first image, a current value of the operating parameter when the first image is acquired is measured;
the second processor generates the noise data by extrapolating the reference image based on the reference value and the current value of the operating parameter and a model describing the behavior of the fixed pattern noise as a function of the operating parameter. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification