Method and apparatus for recovering audio signals from images
First Claim
1. A method of recovering audio signals, the method comprising:
- deriving representations of local motions of different portions of a surface from a series of optical images of features of the different portions of the surface, the series of optical images having been captured with the surface in a presence of a sound, and deriving the representations of local motions including decomposing each image of the series of optical images into multiple dimensions using a complex steerable pyramid structure;
combining the representations of local motions of different portions of the surface to produce a global motion signal of the surface; and
producing an audio signal of the sound based on the global motion signal of the surface having been located in the presence of the sound.
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Abstract
A method of recovering audio signals and corresponding apparatus according to an embodiment of the present invention using video or other sequence of images enables recovery of sound that causes vibrations of a surface. An embodiment method includes combining representations of local motions of a surface to produce a global motion signal of the surface. The local motions are captured in a series of images of features of the surface, and the global motion signal represents a sound within an environment in which the surface is located. Some embodiments compare representations of local motions of a surface to determine which motions are in-phase or out-of-phase with each other, enabling visualization of surface vibrational modes. Embodiments are passive, as compared to other forms of remote audio recovery that employ active sensing, such as laser microphone systems. Example applications for the embodiments include espionage and surveillance.
29 Citations
39 Claims
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1. A method of recovering audio signals, the method comprising:
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deriving representations of local motions of different portions of a surface from a series of optical images of features of the different portions of the surface, the series of optical images having been captured with the surface in a presence of a sound, and deriving the representations of local motions including decomposing each image of the series of optical images into multiple dimensions using a complex steerable pyramid structure; combining the representations of local motions of different portions of the surface to produce a global motion signal of the surface; and producing an audio signal of the sound based on the global motion signal of the surface having been located in the presence of the sound. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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15. An audio signal recovery apparatus comprising:
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memory configured to store representations of local motions of different portions of a surface, the local motions having been captured in a series of optical images of features of the different portions of the surface with the surface located in a presence of a sound; and a processor configured to derive the representations of local motions by decomposing each image of the series of optical images into multiple dimensions using a complex steerable pyramid structure, the processor further configured to combine the representations of local motions of the surface to produce a global motion signal of the surface, the processor further configured to produce an audio signal of the sound based on the global motion signal of the surface having been located in the presence of the sound. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 39)
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29. A method comprising:
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deriving representations of local motions of different portions of a surface from a series of optical images of features of the different portions of the surface, the series of optical images having been captured with the surface in a presence of a sound, and deriving the representations of local motions including decomposing each image of the series of optical images into multiple dimensions using a complex steerable pyramid structure; comparing the representations of local motions of different portions of the surface to make a determination of which local motions are in-phase or out-of-phase with each other; and recovering one or more vibration mode shapes of the surface based on the determination of which local motions are in-phase or out-of-phase with each other.
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Specification