• Acta Photonica Sinica
  • Vol. 39, Issue 10, 1901 (2010)
HU Feng-ping1, CHANG Yi-lin1, MA Yan-zhuo1, and ZHAO Guang-yao2
Author Affiliations
  • 1[in Chinese]
  • 2[in Chinese]
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    DOI: Cite this Article
    HU Feng-ping, CHANG Yi-lin, MA Yan-zhuo, ZHAO Guang-yao. Development of the Video Automatic Focus Method[J]. Acta Photonica Sinica, 2010, 39(10): 1901 Copy Citation Text show less

    Abstract

    An automatic camera focusing scheme used in video conference is presented.The proposed scheme consists of two phases: focus adjusting and focus monitoring.In the focus adjusting phase,mountain climbing algorithm is used to search the peak point of the focusing criteria function.The focus searching range is reduced by the concept of hyperfocal distance,and the searching step size is adapted dynamically.Therefore,the searching process is speeded up,and good subjective quality of pictures is guaranteed.Moreover,to eliminate the influence of scene changes during the searching process,a return-examination method is used.In the focus monitoring phase,focus adjusting is conditionally triggered based on the results of shot change detection,which helps to guarantee focus quality and avoid frequently refocusing.Experimental results validate the performance and robustness of the proposed scheme.It has been integrated in the products of video conference terminal.
    HU Feng-ping, CHANG Yi-lin, MA Yan-zhuo, ZHAO Guang-yao. Development of the Video Automatic Focus Method[J]. Acta Photonica Sinica, 2010, 39(10): 1901
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