Approximation of discrete cosine transform (DCT)

is useful for reducing its computational complexity without significant

impact on its coding performance. Most of the existing

algorithms for approximation of the DCT target only the DCT of

small transform lengths, and some of them are non-orthogonal.

This paper presents a generalized recursive algorithm to obtain

orthogonal approximation of DCT where an approximate DCT

of length could be derived a pair of DCTs of length

at the cost of additions for input preprocessing.-Approximation of discrete cosine transform (DCT)

is useful for reducing its computational complexity without significant

impact on its coding performance. Most of the existing

algorithms for approximation of the DCT target only the DCT of

small transform lengths, and some of them are non-orthogonal.

This paper presents a generalized recursive algorithm to obtain

orthogonal approximation of DCT where an approximate DCT

of length could be derived　a pair of DCTs of length

at the cost of additions for input preprocessing.