Back to results
US 9,847,976 B2Granted
Shared secret arrangements and optical data transfer
AssigneeDigimarc Corporation
InventorsJohn D. Lord, John Stach
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeDigimarc Corporation
InventorsJohn D. Lord, John Stach
Estimating the term…
Digital data is optically broadcast through an environment by controllably switching the brightness or chrominance of LED solid state lamps, or of other illumination sources (e.g., television screens and backlit computer displays). This optical data channel is useful to convey cryptographic key data by which devices within the environment can authenticate themselves to a secure network. In some embodiments, the optical modulation is sensed by the camera of a smartphone. The row data output by the smartphone's camera sensor is processed to extract the modulated data signal. In some monochrome embodiments, data communication speeds far in excess of the camera's frame rate (e.g., 30/second), or even the camera's row rate (e.g., 14,400/second) are achieved. Still greater rates can be achieved by conveying different data in different chrominance channels. A great number of other features and arrangements are also detailed.
A method employing a mobile video camera that includes plural rows of photodetectors, each row producing pixel data, the method comprising the acts:
A method of optical signaling, using a portable device camera comprising rows of pixels operated in a rolling shutter fashion, wherein one row of a captured image frame is exposed starting at a first time and ending at a second time, and a next row of said captured image frame is exposed starting at a third time after the first time and before the second time, and ending at a fourth time after the second time, and wherein the camera captures frames of imagery in a video mode at N frames per second, and the method includes processing row data of the captured frames to extract an optical data signal having a data rate greater than N symbols per second.
A portable user device equipped with a camera, a processor and a memory, the memory containing instructions configuring the device to perform acts including:
A non-transitory computer memory containing software instructions enabling a camera-equipped device to perform acts including:
A method employing a camera-equipped portable device, comprising the acts:
Dependencies are inferred from the claim text.