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Color demosaicking by local directional interpolation and nonlocal adaptive thresholding

[+] Author Affiliations
Lei Zhang

The Hong Kong Polytechnic University, Department of Computing, Hung Hom, Kowloon, Hong Kong, China

Xiaolin Wu

McMaster University, Department of Electrical and Computer Engineering, Hamilton, Ontario, L8G 4K1, Canada

Antoni Buades

Université Paris Descartes, 45, rue des Saints Pères, 7ème ètage, 75270 Paris Cedex 06, France

Xin Li

West Virginia University, Lane Department of Computer Science and Electrical Engineering, PO Box 6109, Morgantown, West Virginia 26506

J. Electron. Imaging. 20(2), 023016 (June 27, 2011). doi:10.1117/1.3600632
History: Received October 26, 2010; Revised May 03, 2011; Accepted May 25, 2011; Published June 27, 2011; Online June 27, 2011
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Single sensor digital color cameras capture only one of the three primary colors at each pixel and a process called color demosaicking (CDM) is used to reconstruct the full color images. Most CDM algorithms assume the existence of high local spectral redundancy in estimating the missing color samples. However, for images with sharp color transitions and high color saturation, such an assumption may be invalid and visually unpleasant CDM errors will occur. In this paper, we exploit the image nonlocal redundancy to improve the local color reproduction result. First, multiple local directional estimates of a missing color sample are computed and fused according to local gradients. Then, nonlocal pixels similar to the estimated pixel are searched to enhance the local estimate. An adaptive thresholding method rather than the commonly used nonlocal means filtering is proposed to improve the local estimate. This allows the final reconstruction to be performed at the structural level as opposed to the pixel level. Experimental results demonstrate that the proposed local directional interpolation and nonlocal adaptive thresholding method outperforms many state-of-the-art CDM methods in reconstructing the edges and reducing color interpolation artifacts, leading to higher visual quality of reproduced color images.

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© 2011 SPIE and IS&T

Citation

Lei Zhang ; Xiaolin Wu ; Antoni Buades and Xin Li
"Color demosaicking by local directional interpolation and nonlocal adaptive thresholding", J. Electron. Imaging. 20(2), 023016 (June 27, 2011). ; http://dx.doi.org/10.1117/1.3600632


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