COMPUTATIONALLY EFFICIENT ALGORITHM FOR PARALLEL IMPLEMENTATION OF ZEROTREE CODING
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This paper presents a computationally efficient algorithm for the parallel implementation of Embedded Zerotree Coding (EZW) using an integer-based lifted wavelet transform. By optimizing key areas of the EZW algorithm and integrating lifting techniques, we achieve significant reductions in complexity and memory requirements, eliminating the need for floating-point units. The proposed methods include in-place processing, parallel zerotree identification, and efficient memory management, resulting in enhanced runtime performance. Future work aims to further explore pipelining and optimal parallel stages for diverse input sizes.
COMPUTATIONALLY EFFICIENT ALGORITHM FOR PARALLEL IMPLEMENTATION OF ZEROTREE CODING
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COMPUTATIONALLY EFFICIENT ALGORITHM FOR PARALLEL IMPLEMENTATION OF ZEROTREE CODING Saikat Mandal Yogesh Jashnani Prof. Yu Hen Hu ECE 734 Spring 2004
Motivation • Perform an in-depth analysis of Embedded Zerotree coding (EZW) • Identify areas of optimization in the algorithm • Apply concepts learned in class for efficient hardware implementation of EZW • Incorporate integer based lifted wavelet algorithm to reduce complexity
Approach 1:DWT • Use of lifting leads to speed-up compared to FWT, reduces MAC operations • In-place Implementation • Introduces parallelism within the wavelet computation, and with EZW • Integer based approach • Reduces memory requirements (float to int) • No need of floating point units on chip
Psedo Code of Integer based transform Forward Inverse For i = M : 1 For i = 1: M end end
Approach 2:Embedded Zerotree Coding (EZW) • Incorporate a fast technique to identify zerotrees prior to encoding. • Simple Bit-wise ORing operation to determine the elements of zerotree. • Scale-1 zerotree coefficients are discarded after first step, saving 3/4th memory required to store the zerotree. • Initialize a zerotree map whose elements are determined in parallel with wavelet transform operation.
Lifting – EZW interface • Literature focuses on EZW or lifting, not on combination of the two • Lifting and Zerotree identification can be done in parallel • 3 more lifting steps are needed for the scaling coefficient in integer based transform • scaling SKIPPED in most algorithms, but VITAL for EZW
RESULTS (1) • Entire algorithm was implemented in ANSI C • PSNR • Memory(512x512 1byte/pixel) SPIHT : 1.125 MB
RESULTS (2) • Computational costs[1] • Runtime speed (in ms)
FUTURE WORK • Further investigate the parallel implementation of lifting and EZW • Find optimum solution for number of parallel stages and level of pipelining such that HUE is maximum for a wide range of input image sizes and levels of decomposition • Listless Encoding