CMOS image sensors with feature extraction
First Claim
1. A method of operating a complementary metal oxide semiconductor (CMOS) imaging sensor having a pixel array and pixel processing circuitry, comprising the steps of:
- (a) operating the CMOS imaging sensor in an in-pixel motion-detecting mode at a first power level using circuitry on the imaging sensor that generates motion data based on received images detected by pixels in the pixel array, wherein when in the in-pixel motion-detecting mode, a pair of pixels in the pixel array are merged and a previous frame signal generated by the merged pixels and a current frame signal generated by the merged pixels are compared by an in-pixel comparator to determine a frame difference therebetween, and further wherein a quantized frame-difference signal is generated by the in-pixel comparator when motion is detected based on the frame difference;
(b) switching the imaging sensor from the motion-detecting mode to a feature extraction mode in response to detecting motion; and
(c) operating the imaging sensor in the feature extraction mode at a second power level that is higher than the first power level, wherein operating in the feature extraction mode comprises;
receiving pixel data from the pixel array;
calculating spatial gradients based on the received pixel data;
determining angular information associated with the spatial gradients using a gradient-to-analog converter comprising mixed-signal processing circuitry by;
converting the spatial gradients into analog values;
generating an analog trigonometric value of the spatial gradients; and
determining angular information associated with the spatial gradients based on the analog trigonometric value; and
determining magnitudes of the spatial gradients associated with the angular information;
wherein the imaging sensor generates extracted feature data from one or more received images when operating in the feature extraction mode.
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Abstract
A CMOS imaging sensor with embedded feature extraction capability operatable in different modes by a method that includes the steps of: (a) operating the CMOS imaging sensor in a motion-detecting mode at a first power level using circuitry on the imaging sensor that generates motion data based on received images detected by pixels in the pixel array; (b) switching the imaging sensor from the motion-detecting mode to a feature extraction mode in response to detecting motion; and (c) operating the imaging sensor in the feature extraction mode at a second power level that is higher than the first power level.
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Citations
15 Claims
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1. A method of operating a complementary metal oxide semiconductor (CMOS) imaging sensor having a pixel array and pixel processing circuitry, comprising the steps of:
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(a) operating the CMOS imaging sensor in an in-pixel motion-detecting mode at a first power level using circuitry on the imaging sensor that generates motion data based on received images detected by pixels in the pixel array, wherein when in the in-pixel motion-detecting mode, a pair of pixels in the pixel array are merged and a previous frame signal generated by the merged pixels and a current frame signal generated by the merged pixels are compared by an in-pixel comparator to determine a frame difference therebetween, and further wherein a quantized frame-difference signal is generated by the in-pixel comparator when motion is detected based on the frame difference; (b) switching the imaging sensor from the motion-detecting mode to a feature extraction mode in response to detecting motion; and (c) operating the imaging sensor in the feature extraction mode at a second power level that is higher than the first power level, wherein operating in the feature extraction mode comprises; receiving pixel data from the pixel array; calculating spatial gradients based on the received pixel data; determining angular information associated with the spatial gradients using a gradient-to-analog converter comprising mixed-signal processing circuitry by; converting the spatial gradients into analog values; generating an analog trigonometric value of the spatial gradients; and determining angular information associated with the spatial gradients based on the analog trigonometric value; and determining magnitudes of the spatial gradients associated with the angular information; wherein the imaging sensor generates extracted feature data from one or more received images when operating in the feature extraction mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of operating a complementary metal oxide semiconductor (CMOS) imaging sensor having a pixel array and pixel processing circuitry in an in-pixel motion detecting mode using circuitry on the imaging sensor that generates motion data based on received images detected by pixels in the pixel array, comprising:
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sampling, by a first in-pixel capacitor of one of a pair of pixels, an analog previous frame signal, wherein the analog previous frame signal is sampled by connecting the two pixels of the pair of pixels to the first in-pixel capacitor; sampling, by a second in-pixel capacitor of the other of the pair of pixels, an analog current frame signal, wherein the analog current frame signal is sampled by connecting the two pixels of the pair of pixels to the second in-pixel capacitor; determining, by one or more in-pixel transistors reconfigured as an in-pixel comparator, a frame difference between the analog previous and current frame signals sampled by the first and second in-pixel capacitors, respectively; and generating, by the one or more in-pixel transistors reconfigured as the in-pixel comparator, a quantized digital frame-difference signal when motion is detected based on the frame difference. - View Dependent Claims (14, 15)
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Specification