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Appl. Sci. 2016, 6(5), 140;

A Novel Image Alignment Algorithm Based on Rotation-Discriminating Ring-Shifted Projection for Automatic Optical Inspection

Graduate Institute of Automation Technology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd, Taipei 10608, Taiwan
Author to whom correspondence should be addressed.
Academic Editor: Chien-Hung Liu
Received: 24 December 2015 / Revised: 13 April 2016 / Accepted: 29 April 2016 / Published: 9 May 2016
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This paper proposes a novel image alignment algorithm based on rotation-discriminating ring-shifted projection for automatic optical inspection. This new algorithm not only identifies the location of the template image within an inspection image but also provides precise rotation information during the template-matching process by using a novel rotation estimation scheme, the so-called ring-shifted technique. We use a two stage framework with an image pyramid searching technique for realizing the proposed image alignment algorithm; in the first stage, the similarity based on hybrid projection transformation with the image pyramid searching technique is employed for quick selection and location of the candidates in the inspection image. In the second stage, the rotation angle of the object is estimated by a novel ring-shifted technique. The estimation is performed only for the most likely candidate which is the one having the highest similarity in the first stage. The experimental results show that the proposed method provides accurate estimation for template matching with arbitrary rotations and is applicable in various environmental conditions. View Full-Text
Keywords: image alignment; rotation-discriminating; ring-shifted projection; image entropy image alignment; rotation-discriminating; ring-shifted projection; image entropy

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Chen, C.-S.; Huang, C.-L. A Novel Image Alignment Algorithm Based on Rotation-Discriminating Ring-Shifted Projection for Automatic Optical Inspection. Appl. Sci. 2016, 6, 140.

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