Journal of Zhejiang University SCIENCE C

, Volume 14, Issue 12, pp 930–940 | Cite as

An efficient projection defocus algorithm based on multi-scale convolution kernel templates

  • Bo Zhu
  • Li-jun Xie
  • Guang-hua Song
  • Yao Zheng


The focal problems of projection include out-of-focus projection images from the projector caused by incomplete mechanical focus and screen-door effects produced by projection pixilation. To eliminate these defects and enhance the imaging quality and clarity of projectors, a novel adaptive projection defocus algorithm is proposed based on multi-scale convolution kernel templates. This algorithm applies the improved Sobel-Tenengrad focus evaluation function to calculate the sharpness degree of intensity equalization and then constructs multi-scale defocus convolution kernels to remap and render the defocus projection image. The resulting projection defocus corrected images can eliminate out-of-focus effects and improve the sharpness of uncorrected images. Experiments show that the algorithm works quickly and robustly and that it not only effectively eliminates visual artifacts and can run on a self-designed smart projection system in real time but also significantly improves the resolution and clarity of the observer’s visual perception.

Key words

Projection focal Sobel-Tenengrad evaluation function Projector defocus Multi-scale convolution kernels 

CLC number



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Copyright information

© Journal of Zhejiang University Science Editorial Office and Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Bo Zhu
    • 1
    • 2
  • Li-jun Xie
    • 1
    • 2
  • Guang-hua Song
    • 1
    • 2
  • Yao Zheng
    • 1
    • 2
  1. 1.School of Aeronautics and AstronauticsZhejiang UniversityHangzhouChina
  2. 2.Center for Engineering and Scientific ComputationZhejiang UniversityHangzhouChina

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