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Journal of Electronic Imaging

Color demosaicking by local directional interpolation and nonlocal adaptive thresholding
Author(s): Lei Zhang; Xiaolin Wu; Antoni Buades; Xin Li
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Paper Abstract

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.

Paper Details

Date Published: 1 April 2011
PDF: 17 pages
J. Electron. Imag. 20(2) 023016 doi: 10.1117/1.3600632
Published in: Journal of Electronic Imaging Volume 20, Issue 2
Show Author Affiliations
Lei Zhang, The Hong Kong Polytechnic Univ. (Hong Kong, China)
Xiaolin Wu, McMaster Univ. (Canada)
Antoni Buades, Univ. Paris Descartes (France)
Xin Li, West Virginia Univ. (United States)

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