Scene Adaptive Auto Exposure
First Claim
1. A scene adaptive auto exposure system comprising:
- an image sensor for capturing an image representative of a scene;
a memory coupled to the image sensor; and
a programmable control device communicatively coupled to the image sensor and the memory, wherein the memory includes instructions for causing the programmable control device to perform a scene adaptive auto exposure method on image information received from the image sensor, the method comprising;
defining a first exposure metering region over a desired area of the image;
defining a plurality of second exposure metering regions, wherein each second exposure metering region covers a desired area of the image;
comparing a value for each of the second exposure metering regions to a value for the first exposure metering region;
determining a scene identifier based on the compared values;
determining a metering value for the scene based at least in part on the determined scene identifier; and
setting an exposure parameter for the image sensor based at least in part on the determined metering value.
1 Assignment
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Accused Products
Abstract
Systems, methods, and a computer readable medium for an improved automatic exposure algorithm attempt to classify an image into a particular “scene category,” and, based on the determined scene category, meter the scene according to a generated metering weighting matrix. In one embodiment, the average luminance is calculated for a central exposure metering region of the image and a plurality of peripheral exposure metering regions surrounding the central exposure metering region. Based on comparisons of the average luminance values of the peripheral exposure regions to the average luminance of the central exposure region, a target metering weighting matrix may be generated. In another embodiment, the scene category corresponds to a predetermined metering weighting matrix. In video applications, it may be desirable to reduce oscillations in metering parameter values to limit any visually jarring effects on the camera'"'"'s preview screen by only adjusting metering parameter values when predetermined criteria are met.
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Citations
25 Claims
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1. A scene adaptive auto exposure system comprising:
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an image sensor for capturing an image representative of a scene; a memory coupled to the image sensor; and a programmable control device communicatively coupled to the image sensor and the memory, wherein the memory includes instructions for causing the programmable control device to perform a scene adaptive auto exposure method on image information received from the image sensor, the method comprising; defining a first exposure metering region over a desired area of the image; defining a plurality of second exposure metering regions, wherein each second exposure metering region covers a desired area of the image; comparing a value for each of the second exposure metering regions to a value for the first exposure metering region; determining a scene identifier based on the compared values; determining a metering value for the scene based at least in part on the determined scene identifier; and setting an exposure parameter for the image sensor based at least in part on the determined metering value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A scene adaptive auto exposure system comprising:
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an image sensor for capturing an image representative of a scene; a memory coupled to the image sensor; and a programmable control device communicatively coupled to the image sensor and the memory, wherein the memory includes instructions for causing the programmable control device to perform a scene adaptive auto exposure method on image information received from the image sensor, the method comprising; defining a first exposure metering region over a desired area of the image; defining a plurality of second exposure metering regions, wherein each second exposure metering region covers a desired area of the image; comparing a value for each of the second exposure metering regions to a value for the first exposure metering region; assigning a target weight value to each of the plurality of second exposure metering regions based on the outcome of the comparison of the value for the second exposure metering region to the value for the first exposure metering region; determining a metering value for the scene based at least in part on a calculated weighted average value for the scene; and setting an exposure parameter for the image sensor based at least in part on the determined metering value. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method of auto exposing a physical scene comprising:
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receiving from an image sensor image information representative of the physical scene and comprising a plurality of pixels; defining exposure metering regions over two or more desired areas within the physical scene, wherein each region comprises a subset of the plurality of pixels; determining a metering value for the physical scene based at least in part on a comparison of luminance values of pixels in a first exposure metering region to luminance values of pixels in a second exposure metering region; and setting an exposure parameter for the image sensor based at least in part on the determined metering value. - View Dependent Claims (18, 19, 20, 21, 22, 23, 25)
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24. A method of auto exposing a physical scene comprising:
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receiving from an image sensor image information representative of the physical scene and comprising a plurality of pixels; defining a pattern of exposure metering regions over two or more desired areas within the physical scene, wherein each area comprises a subset of the plurality of pixels; comparing an average luminance value of pixels in a first exposure metering region to an average luminance value of pixels in a second exposure metering region; determining a scene category based on the outcome of the compared average luminance values; selecting a predetermined metering weighting matrix corresponding to the determined scene category, wherein the metering weighting matrix comprises a target weight value for each exposure metering region; and setting an exposure parameter for the image sensor based at least in part on the target weight values in the selected predetermined metering weighting matrix.
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Specification