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Auto-focus calibration for image capture device

An autofocus and image technology, applied in focusing devices, image communication, components of color TV, etc., can solve the problems of undesired power consumption, differences in autofocus performance, etc.

Active Publication Date: 2014-02-26
QUALCOMM INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Moving the lens to multiple lens positions within the search range can result in autofocus latency and undesired power consumption
Additionally, manufacturing characteristics of lens modules may vary, resulting in differences in autofocus performance

Method used

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  • Auto-focus calibration for image capture device
  • Auto-focus calibration for image capture device
  • Auto-focus calibration for image capture device

Examples

Experimental program
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Embodiment Construction

[0021] This disclosure relates to techniques for calibrating an autofocus process in an image capture device. An image capture device includes an image sensor that senses an image via a lens. The autofocus process generally involves moving the lens between different candidate lens positions within a search range, calculating a focus value at each of the positions and selecting one of the positions as the captured image based on the focus value best position. A focus value may be determined for a given frame to be captured based on a degree of focus, eg, an image sharpness metric. The sharpness metric may be determined, for example, based on contrast characteristics of pixel values ​​generated by a sensor associated with the image capture device. To reduce auto-focus latency, the image capture device may apply a search algorithm to more efficiently select a relatively small number of candidate locations within the search range.

[0022] A lens module typically includes at le...

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PUM

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Abstract

The disclosure relates to techniques for calibration of an auto-focus process in an image capture device. The techniques may involve calibration of a lens actuator used to move a lens within a search range during an auto-focus process. For example, an image capture device may adjust reference positions for the search range based on lens positions selected for different focus conditions. The different focus conditions may include a far focus condition and a near focus condition. The focus conditions may be determined based on a detected environment in which the device is used. Detection of an indoor environment may indicate a likelihood of near object focus, while detection of an outdoor environment may indicate a likelihood of far object focus. An image capture device may detect indoor and outdoor environments based on lighting, exposure, or other conditions.

Description

technical field [0001] This disclosure relates to image capture devices, and more particularly, to autofocus techniques for image capture devices, such as cameras. Background technique [0002] Image capture devices such as digital video cameras or digital still cameras are used in different applications and environments. The image capture device should be able to produce high quality images from multiple distances with respect to scene objects. A typical image capture device may perform an autofocus process to select a position of a lens within the image capture device that achieves sharp focus on an image frame of a scene. Captured images or videos may look blurry without proper focus. [0003] The image capture device may perform an active autofocus process, a passive autofocus process, or a combination of both processes. In the case of passive autofocus, an autofocus process implemented by the image capture device may calculate focus values ​​(eg, image sharpness metr...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G03B13/32H04N5/232
CPCH04N5/23212H04N23/67
Inventor 李京强塞波·罗伯特·洪安德鲁·秋·秦川
Owner QUALCOMM INC