Time synchronization in an image processing circuit
AssigneeNXP B.V.
InventorsAnirban Lahiri, Alexander Alexandrovich Danilin
Life of this patent
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Abstract
A controllable light source (102) is controlled to emit modulated light, preferably using a uniquely recognizable modulation pattern. A plurality of camera units (10) captures images that contain the light source. Clock time values at a time corresponding to capture of the image are captured from respective clock circuits (120) associated with the camera units (10) that capture the images. The modulated light is detected in the captured images. Relative calibration of the clock circuits (120) with respect to each other is performed using the associated clock time values of the images wherein the modulated light is detected.
Claims12
An image processing system comprising:
- a plurality of clock circuits;
- a plurality of camera units, each having an associated clock circuit from the plurality of clock circuits, each said camera unit being configured to capture images associated with clock time values captured from the associated clock circuit of the camera unit at a time corresponding to capture of the image;
- a controllable light source;
- processing circuitry coupled to the camera units and the controllable light source and configured to cause the controllable light source to emit modulated light, to detect the modulated light in the captured images and to determine a relative calibration of the clock circuits with respect to each other from the associated clock time values of the images, wherein the modulated light is detected.
An image processing system according to claim 5, wherein the processing circuitry is configured to cause the modulation patterns of respective ones of the light sources to represent respective different codewords of an error correcting code.
A camera unit comprising:
- a clock circuit;
- a camera;
- a controllable light source;
- a camera control circuit with a communication network interface, the camera control circuit being coupled to the clock circuit, the camera and the controllable light source, the camera control circuit being configured to control the controllable light source to emit a pattern of modulation, to sample a clock time value of the clock circuit associated with a time of emission, to sample further clock time values of the clock circuit at which further patterns of modulation are detected in images captured by the camera and to transmit information representing the sampled clock time values via the network interface.
A method of operating an image processing system, the method comprising:
- causing a controllable light source to emit modulated light;
- capturing images that contain the light source from a plurality of camera units respectively;
- capturing clock time values at a time corresponding to capture of the image from respective clock circuits associated with the camera units that capture the images respectively;
- detecting the modulated light in the captured images;
- and
- determining a relative calibration of the clock circuits with respect to each other from the associated clock time values of the images wherein the modulated light is detected.
Dependencies are inferred from the claim text.