Factorization of nonuniform block orthogonal transforms

Block orthogonal transforms (BOTs) are commonly used for lots of applications. Conventional BOTs are based on uniform filter banks, however, nonuniform BOTs are often superior to uniform ones. In this research, we investigate the factorization of nonuniform BOTs which does not involve the tree structure. Therefore, optimal nonuniform BOTs are available in the sense of transform coding gain. Some design examples are included to confirm our theory. We also apply the nonuniform BOT to the transform image coding.