Color Demosaicing Using Asymmetric Directional Interpolation and Hue Vector Smoothing

Yoshihisa TAKAHASHI  Kentaro HIRAKI  Hisakazu KIKUCHI  Shogo MURAMATSU  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E91-A   No.4   pp.978-986
Publication Date: 2008/04/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e91-a.4.978
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Selected Papers from the 20th Workshop on Circuits and Systems in Karuizawa)
image processing,  color demosaicing,  interpolation,  CFA,  

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This paper presents a color demosaicing method applied to the Bayer pattern color filter array (CFA). Reliable estimation of an edge direction, edge-directed asymmetric interpolation, and the use of color samples at immediate neighbors are considered as the key guidelines for smooth and sharp image restoration. Also, special interest is directed to local areas that are rich in high spatial frequency variations. For suppression of false colors likely to occur in those areas, a hue vector representation is introduced so that the spatial correlation between different color components may be exploited in consistent with the local constant-hue principle. Smoothing is repeated in the hue vector field a few times. Experimental results have shown preferable performances in terms of PSNR, CIELAB color difference, hue angle difference, CIE chromaticity and visual appearance, in particular resulting in less false colors.