Type of Document	Master's Thesis
Author	Appia, Vikram V
Author's Email Address	vikram.appia@gatech.edu
URN	etd-03262008-121043
Title	A COLOR FILTER ARRAY INTERPOLATION METHOD FOR DIGITAL CAMERAS USING ALIAS CANCELLATION
Degree	Master of Science
Department	Electrical and Computer Engineering
Advisory Committee	Advisor Name Title Russell Mersereau Committee Chair Anthony J. Yezzi Committee Member Yucel Altunbasak Committee Member
Keywords	demosaicking bayer array projection onto convex sets cfa interpolation color filter array interpolation adaptive homogeneity alias cancellation
Date of Defense	2008-03-26
Availability	unrestricted
Abstract To reduce cost, many digital cameras use a single sensor array instead of using three arrays for the red, green and blue. Thus at each pixel location only the red, green or blue intensity value is available. And to generate a complete color image, the camera must estimate the missing two values at each pixel location .Color filter arrays are used to capture only one portion of the spectrum (Red, Green or Blue) at each location. Various arrangements of the Color Filter Array (CFA) are possible, but the Bayer array is the most commonly used arrangement and we will deal exclusively with the Bayer array in this thesis. Since each of the three colors channels are effectively downsampled, it leads to aliasing artifacts. This thesis will analyze the effects of aliasing in the frequency- domain and present a method to reduce the deterioration in image quality due to aliasing artifacts. Two reference algorithms, AH-POCS (Adams and Hamilton - Projection Onto Convex Sets) and Adaptive Homogeneity-Directed interpolation, are discussed in de- tail. Both algorithms use the assumption that there is high correlation in the high- frequency regions to reduce aliasing. AH-POCS uses alias cancellation technique to reduce aliasing in the red and blue images, while the Adaptive Homogeneity-Directed interpolation algorithm is an edge-directed algorithm. We present here an algorithm that combines these two techniques and provides a better result on average when compared to the reference algorithms.
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