A fast encoding method for vector quantization using modified memory-efficient sum pyramid

Based on the concept of multi-resolutions, full search (FS) equivalent fast search methods for vector quantization (VQ) using mean-type pyramid have been developed in previous work.^1-4) In this paper, a modified memory-efficient sum pyramid is proposed, which is exact for computing the difference in integer form and features one more new resolution L₀₁ in-between the top 2 levels L₀ and L₁ of a conventional pyramid. Benefiting from a recursive difference computation at the top 3 levels, the proposed method can reduce the total computational cost obviously. Furthermore, a memory-efficient way of storage for the top 3 levels is integrated to reduce extra memory requirement.