SENSOR DARK PIXEL OFFSET ESTIMATION
First Claim
1. A method for correcting for dark current in a photosensor comprising a plurality of pixels, the method comprising:
- under control of one or more physical computing devices configured with specific computer-executable instructions,accessing a scale factor and a bias factor for the plurality of pixels of the photosensor, the scale factor and the bias factor depending at least partly on a temperature of the photosensor and a gain of the photosensor, the scale factor having the same value for each pixel in the plurality of pixels, and the bias factor having the same value for each pixel in the plurality of pixels;
for each pixel in the plurality of pixels of the photosensor;
accessing a pixel value that represents a response of the pixel to receipt of light;
accessing an offset value for the pixel, the offset value not dependent on the temperature or the gain of the photosensor;
determining a corrected pixel value that depends at least partly on the pixel value, the scale factor, the bias factor, and the offset; and
providing the corrected pixel value.
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Accused Products
Abstract
Examples of systems and methods to provide estimates of dark current for pixels of a photosensor as a function of the temperature of the sensor and the gain applied to the photosensor are described. In various implementations, the dark current estimated for each pixel can depend at least partly on a global scale factor and a global bias that depend on temperature and gain and a temperature-independent and gain-independent offset value for each pixel. The scale, bias, and offsets may be determined from multiple dark field images taken by the sensor over a range of operating temperatures. In some cases, the scale and bias can be determined using a subset of less than all the image pixels. Scale and bias derived for a particular sensor can be used in the calibration of different sensors.
45 Citations
39 Claims
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1. A method for correcting for dark current in a photosensor comprising a plurality of pixels, the method comprising:
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under control of one or more physical computing devices configured with specific computer-executable instructions, accessing a scale factor and a bias factor for the plurality of pixels of the photosensor, the scale factor and the bias factor depending at least partly on a temperature of the photosensor and a gain of the photosensor, the scale factor having the same value for each pixel in the plurality of pixels, and the bias factor having the same value for each pixel in the plurality of pixels; for each pixel in the plurality of pixels of the photosensor; accessing a pixel value that represents a response of the pixel to receipt of light; accessing an offset value for the pixel, the offset value not dependent on the temperature or the gain of the photosensor; determining a corrected pixel value that depends at least partly on the pixel value, the scale factor, the bias factor, and the offset; and providing the corrected pixel value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for correcting for dark current in a sensor comprising a plurality of pixels, the system comprising:
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physical data storage configured to store; (i) a scale factor applicable to the plurality of pixels, (ii) a bias factor applicable to the plurality of pixels, and (iii) an offset value for each pixel in the plurality of pixels, wherein the scale factor and the bias factor depend at least partly on a temperature of the sensor and a gain of the sensor, and the offset value does not depend on the temperature or the gain of the sensor; and a physical computer processor in communication with the physical data storage, the physical computer processor configured to; access the scale factor and the bias factor; access a pixel value representing an output of a pixel in the plurality of pixels; access the offset value for the pixel in the plurality of pixels; and determine a corrected pixel value for the pixel, wherein the corrected pixel value depends at least partly on the pixel value, the scale factor, the bias factor, and the offset value. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method for estimating dark current in a sensor comprising a plurality of pixels, the method comprising:
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under control of one or more computing devices configured with specific computer-executable instructions, accessing a dark current value for each of the plurality of pixels in the sensor; fitting the dark current values for the plurality of pixels to a dark current model, wherein the dark current model is based at least partly on; a scale factor; a bias factor; and an offset, wherein the scale factor and the bias factor depend at least partly on a temperature of the sensor, the scale factor has a first same value for all the pixels in the plurality of pixels, the bias factor has a second same value for all the pixels in the plurality of pixels, the offset is independent of the temperature of the sensor, and the offset has values that can be different for different pixels in the plurality of pixels; and providing the scale factor, the bias factor, and the offset. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A system for estimating dark current in a sensor comprising a plurality of pixels, the system comprising:
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physical data storage configured to store a dark current value for each of the plurality of pixels in the sensor; and a physical computer processor in communication with the physical data storage, the physical computer processor configured to; fit the dark current values for the plurality of pixels to a dark current model, wherein the dark current model is based at least partly on a scale factor, a bias factor, and an offset, the scale factor and the bias factor depending at least partly on a temperature of the sensor, the scale factor having a first same value for all the pixels in the plurality of pixels, the bias factor having a second same value for all the pixels in the plurality of pixels, the offset independent of the temperature of the sensor, and the offset having values that can be different for different pixels in the plurality of pixels; and output the dark current model to the physical data storage. - View Dependent Claims (30)
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31. A method for calibrating a plurality of pixels on a sensor, the method comprising:
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under control of one or more physical computing devices configured with specific computer-executable instructions, accessing a global factor that is the same for each of the plurality of pixels; accessing a local factor for each of the plurality of pixels, the local factor capable of having values that are different for different pixels in the plurality of pixels; accessing a pixel value for a pixel in the plurality of pixels; determining a corrected pixel value for the pixel, wherein the corrected pixel value depends at least partly on the pixel value, the global factor, and the local factor for the pixel; and providing the corrected pixel value. - View Dependent Claims (32, 33, 34, 35)
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36. A method for determining dark current in a second sensor based at least in part on a dark current model for a first sensor that is different from the second sensor, the dark current model for the first sensor comprising a scale factor and a bias factor, the scale factor and the bias factor depending at least partly on temperature, the scale factor and the bias factor each having a respective global value for all the pixels in the first sensor, the method comprising:
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accessing the scale factor and the bias factor for the first sensor; accessing dark current values for pixels of the second sensor; determining, by execution of instructions by a physical computer processor, offset values for each of the pixels of the second sensor, the offset values based at least in part on the dark current values for the second sensor and the scale factor and the bias factor for the first sensor; and providing a dark current model for the second sensor based at least partly on the offset values for each of the pixels of the second sensor and the scale factor and the bias factor for the first sensor. - View Dependent Claims (37, 38, 39)
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Specification