Dynamic exposure metering based on face detection
First Claim
1. A dynamic 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 dynamic auto exposure method on image information received from the image sensor, the method comprising;
detecting one or more faces in the image information;
determining that one or more of the detected faces meet a predetermined criterion;
creating an exposure metering region over the one or more detected faces meeting the predetermined criterion;
determining a first metering value for the scene based at least in part on a weighted average of each created exposure metering region;
setting first exposure parameter for the image sensor based at least in part on the determined first metering value;
exposing the scene based at least in part on the set first exposure parameter;
moving a first one of the created exposure metering regions over a detected face towards a new location of the detected face in the scene, wherein the moving of the first one of the created exposure metering regions occurs according to according to predetermined lag parameters;
determining a second metering value for the scene based at least in part on the new location of first one of the created exposure metering region;
setting a second exposure parameter for the image sensor based at least in part on the determined second metering value; and
exposing the scene based at least in part on the set second exposure parameter.
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Accused Products
Abstract
A system, computer readable medium, and method for dynamically setting a camera'"'"'s exposure parameters based on face detection are disclosed. When taking a picture or video of a person in front of a bright background, standard exposure algorithms tend to overexpose the background. In one embodiment disclosed herein, a face detection algorithm is run on the current picture or video frame, and the exposure metering region is inset over the detected face. Exposure time, gain, or other exposure parameters may be set based on the pixels within the exposure metering region. In another embodiment, the exposure metering region tracks a moving face according to lag parameters so that the exposure metering region remains substantially over the face. In yet another embodiment, a plurality of faces may be tracked, with the exposure parameters set based on a weighted average of the pixels within the plurality of face-containing exposure metering regions.
44 Citations
22 Claims
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1. A dynamic 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 dynamic auto exposure method on image information received from the image sensor, the method comprising; detecting one or more faces in the image information; determining that one or more of the detected faces meet a predetermined criterion; creating an exposure metering region over the one or more detected faces meeting the predetermined criterion; determining a first metering value for the scene based at least in part on a weighted average of each created exposure metering region; setting first exposure parameter for the image sensor based at least in part on the determined first metering value; exposing the scene based at least in part on the set first exposure parameter; moving a first one of the created exposure metering regions over a detected face towards a new location of the detected face in the scene, wherein the moving of the first one of the created exposure metering regions occurs according to according to predetermined lag parameters; determining a second metering value for the scene based at least in part on the new location of first one of the created exposure metering region; setting a second exposure parameter for the image sensor based at least in part on the determined second metering value; and exposing the scene based at least in part on the set second exposure parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A dynamic 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 dynamic auto exposure method on image information received from the image sensor, the method comprising; detecting one or more faces in the image information; determining a primary face based at least in part on a predetermined criterion; creating an exposure metering region over the primary face; determining a metering value for the scene based at least in part on the created exposure metering region; setting an exposure parameter for the image sensor based at least in part on the determined metering value; exposing the scene based at least in part on the set exposure parameter; and removing the exposure metering region over the primary face when the primary face no longer meets the predetermined criterion. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method of dynamically 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; detecting one or more faces in the image information; determining that one or more of the detected faces meet a predetermined criterion; creating an exposure metering region over the one or more detected faces meeting the predetermined criterion; determining a metering value for the physical scene based at least in part on a weighted average of the pixels within each created exposure metering region; and setting an exposure parameter for the image sensor based at least in part on the determined metering value, wherein the act of creating an exposure metering region over the one or more detected faces meeting the predetermined criterion further comprises moving each created exposure metering region that is over a face that has moved since the face was previously detected towards the face'"'"'s current location, and wherein the act of moving occurs according to predetermined lag parameters. - View Dependent Claims (19, 20, 21)
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22. A method of dynamically auto exposing a physical scene comprising:
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receiving image information representative of the physical scene and comprising a plurality of pixels from an image sensor; detecting one or more faces in the image information; determining a primary face based at least in part on a predetermined criterion; creating an exposure metering region over the primary face; determining a metering value for the scene based at least in part on the created exposure metering region; setting an exposure parameter for the image sensor based at least in part on the determined metering value; and updating the location of the exposure metering region as needed to remain over the primary face, wherein the act of updating the location of the exposure metering region comprises moving the exposure metering region towards the current location of the primary face according to predetermined lag parameters.
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Specification