Demosaicking by Alternating Projections: Theory and Fast One-Step Implementation

Color image demosaicking is a key process in the digital imaging pipeline. In this paper, we study a classical demosaicking algorithm based on alternating projections (AP), proposed by Gunturk, Altunbasak and Mersereau in 2002. Since its publication, the AP algorithm has been widely cited and served as a benchmark in a series of more recent papers in the demosaicking literature. Despite impressive performances, a limitation of the AP algorithm is its high computational complexity. We provide three main contributions in this paper. First, we present a rigorous analysis of the convergence property of the AP demosaicking algorithm, showing that it is a contraction mapping, with a unique fixed point. Second, we show that this fixed point is in fact the solution to a constrained quadratic minimization problem, thus establishing the optimality of the AP algorithm. Finally, using the tool of polyphase representation, we show how to obtain the results of the AP algorithm in a single step, imp...

• Type: Journal
• Year: 2010
• Where: TIP
• Authors: Yue M. Lu, Mina Karzand, Martin Vetterli
• Keywords: AP Algorithm, Classical Demosaicking Algorithm, Education, Fixed Point, TIP 2010