Memory-efficient high-speed VLSI implementation of multi-level discrete wavelet transform

Memory requirements and critical path are essential for 2-D Discrete Wavelet Transform (DWT). In this paper, we address this problem and develop a memory-efficient high-speed architecture for multi-level two-dimensional DWT. First, dual data scanning technique is first adopted in 2-D 9/7 DWT processing unit to perform lifting operations, which doubles the throughputs per cycle. Second, for 2-D DWT architecture, the proposed Row Transform Unit and Column Transform Unit take advantage of input sample availabilities and provision computing resources accordingly to optimize the processing speed, in which the number of processors is further optimized to significantly reduce the hardware cost. Third, to address the problem of high cost of memory for the immediate computing results from each level and the computation time as resolution level increases, multiple proposed 2-D DWT units were combined to build a parallel multi-level architecture, which can perform up to six levels of 2-D DWT in a resolution level parallel way on any arbitrary image size at competitive hardware cost. Experimental results demonstrated that the proposed scheme achieves improved hardware performance with significantly reduced on-chip memory resource and computational time, which outperforms the-state-of-the-art schemes and makes it desirable in memory-constrained real-time application systems.