Continuous autofocus based on face detection and tracking

A face detection and auto-focus technology, applied to color TV parts, TV system parts, TVs, etc., can solve problems such as unsatisfactory and slow image capture process

Active Publication Date: 2013-06-12
FOTONATION LTD
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  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Will result in an unsatisfactorily slow image capture process unless further enhancements are provided

Method used

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  • Continuous autofocus based on face detection and tracking
  • Continuous autofocus based on face detection and tracking
  • Continuous autofocus based on face detection and tracking

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Embodiment Construction

[0028]Standard contrast-detect autofocus is slow and hunts when subjects move out of focus. Falling back to contrast detection autofocus when no blurry face is detected can often slow down the process provided by US 2010 / 0208091. A method of using face detection to speed up focusing and reduce hunting in continuous autofocus is provided. Firstly, highly reliable face detection is provided even when faces are not in focus by providing one or more trained classifier sets for out-of-focus faces and / or parts of faces. One could for example provide three sets of face classifiers: one trained for sharp faces, another for somewhat blurry faces, and a third for even blurrier and out-of-focus faces face. Different numbers of classifier ensembles can be trained and used. This advantageous technique will have far fewer undetected cases than the technique of US 2010 / 0208091, resulting in a faster and more reliable image capture process. 如美国专利号7,362,368、7,616,233、7,315,630、7,269,292、7,4...

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Abstract

An autofocus method includes acquiring an image of a scene that includes one or more out of focus faces and/or partial faces. The method includes detecting one or more of the out of focus faces and/or partial faces within the digital image by applying one or more sets of classifiers trained on faces that are out of focus. One or more sizes of the one of more respective out of focus faces and/or partial faces is/are determined within the digital image. One or more respective depths is/are determined to the one or more out of focus faces and/or partial faces based on the one or more sizes of the one of more faces and/or partial faces within the digital image. One or more respective focus positions of the lens is/are adjusted to focus approximately at the determined one or more respective depths.

Description

Background technique [0001] Digital cameras today often include an autofocus mechanism. Two conventional autofocus mechanisms are contrast detection autofocus and phase detection autofocus. [0002] Contrast detection autofocus [0003] With contrast-detection autofocus, the camera lens is initially positioned at the closest focus point. The lens is moved incrementally and image sharpness is estimated at each step. When peak sharpness is reached, lens movement is stopped. Contrast-detection autofocus is used in conventional digital still cameras or DSCs, camcorder camera phones, webcams, and surveillance cameras. Based on pixel-level measurements and fine-grained scanning, they are extremely precise. They can be focused anywhere inside the frame, but they are usually only focused around the center of the frame. However, contrast detection autofocus mechanisms are slow because they involve scanning the focus range. They also do not allow tracking of fetched objects. A ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04N5/232
CPCH04N23/672H04N23/959H04N23/675H04N23/673H04N23/61H04N23/611H04N23/60
Inventor F·纳努C·N·斯坦P·科科朗
Owner FOTONATION LTD
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