Fast recursive algorithms for 2-D discrete cosine transform. (Q1575779)

A new algorithm for computation of two-dimensional (2D) type-III discrete cosine transform is presented. The algorithm is particularly suited to block size \((p_1*2^m)\) by \((p_2*2n)\), where \(p_{1}\) and \(p_{2}\) are odd integers, and \(m\) and \(n\) are non-negative integers. It shows that the 2D type-III DCT can be decomposed into cosine-cosine, cosine-sine, sine-cosine, sine-sine sequences, which can be further decomposed into similar sequences. The proposed algorithm provides the flexibility in choosing block size and has a simple indexing mapping scheme and a fairly regular computation structure. The algorithm also requires a smaller number of arithmetic operations for \(p_{1}=p_{2}=3\).