Next Article in Journal
The Effect on Wireless Sensor Communication When Deployed in Biomass
Previous Article in Journal
Determination of the NOx Loading of an Automotive Lean NOx Trap by Directly Monitoring the Electrical Properties of the Catalyst Material Itself
Sensors 2011, 11(9), 8281-8294; doi:10.3390/s110908281
Article

Robust Automatic Focus Algorithm for Low Contrast Images Using a New Contrast Measure

1,2
, 1
, 2,* , 2
 and 2
Received: 1 August 2011; in revised form: 23 August 2011 / Accepted: 24 August 2011 / Published: 25 August 2011
(This article belongs to the Section Physical Sensors)
View Full-Text   |   Download PDF [747 KB, uploaded 21 June 2014]   |   Browse Figures
Abstract: Low contrast images, suffering from a lack of sharpness, are easily influenced by noise. As a result, many local false peaks may be generated in contrast measurements, making it difficult for the camera’s passive auto-focus system to perform its function of locating the focused peak. In this paper, a new passive auto-focus algorithm is proposed to address this problem. First, a noise reduction preprocessing is introduced to make our algorithm robust to both additive noise and multiplicative noise. Then, a new contrast measure is presented to bring in local false peaks, ensuring the presence of a well defined focused peak. In order to gauge the performance of our algorithm, a modified peak search algorithm is used in the experiments. The experimental results from an actual digital camera validate the effectiveness of our proposed algorithm.
Keywords: auto-focus; low contrast; contrast measure; noise reduction auto-focus; low contrast; contrast measure; noise reduction
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Export to BibTeX |
EndNote


MDPI and ACS Style

Xu, X.; Wang, Y.; Tang, J.; Zhang, X.; Liu, X. Robust Automatic Focus Algorithm for Low Contrast Images Using a New Contrast Measure. Sensors 2011, 11, 8281-8294.

AMA Style

Xu X, Wang Y, Tang J, Zhang X, Liu X. Robust Automatic Focus Algorithm for Low Contrast Images Using a New Contrast Measure. Sensors. 2011; 11(9):8281-8294.

Chicago/Turabian Style

Xu, Xin; Wang, Yinglin; Tang, Jinshan; Zhang, Xiaolong; Liu, Xiaoming. 2011. "Robust Automatic Focus Algorithm for Low Contrast Images Using a New Contrast Measure." Sensors 11, no. 9: 8281-8294.


Sensors EISSN 1424-8220 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert