DWT Architecture

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CHAPTER 3 INTRODUCTION OF DWT 3.1 3-D DWT Architecture The 3-D DWT can be considered as a combination of three one dimensional DWT in the x, y and z directions, as shown in Fig. 3.1. The preliminary work in the DWT processor design is to build 1-D DWT modules, which are composed of high-pass and low-pass filters that perform a convolution of filter coefficients and input pixels. After a one-level of - discrete wavelet transform, the volume of image is decomposed into HHH, HHL, HLH, HLL, LHH, LHL, LLH and LLL signals as shown in the Fig. 3.1 [1]. Fig. 3.1 One-level 3-D DWT structure Recently, a methodology for implementing lifting based DWT has been proposed because of lifting based DWT has many advantages over convolution based one [3-5]. The lifting structure largely reduces the number of multiplication and accumulation where filter bank architectures can take advantage of many low power constant multiplication algorithms. FPGA is used in general in these systems due to low cost and high computing speed with reprogrammable property. 3.2 Lifting Scheme for 1-D DWT using 9/7 Filter The basic idea behind the lifting scheme is very simple; try to use the correlation in the data to remove redundancy [3, 4]. First split the data into two sets (split phase) i.e., odd samples and even samples as shown in Fig. 3.2[1, 2]. Because of the assumed smoothness of the data, we predict that the odd samples have a value that is closely related to their neighbouring even samples. We use N even samples to predict the value of a neighbouring odd value (predict phase). With a good prediction method, the chance is high that the original odd sample is in the same range as its prediction. We calculate the difference between the odd sample and its p... ... middle of paper ... ... are rules to specify in which order they are searched. A common example of using both a working library and a resource library is one where your gate-level design and test-bench are compiled into the working library, and the design references gate-level models in a separate resource library. The diagram below shows the basic steps for simulating with multiple libraries. Fig. 3.9 Basic steps for multiple library flow You can also link to resource libraries from within a project. If you are using a project, you would replace the first step above with these two steps: create the project and add the test-bench to the project. 3.4.2.4 Debugging Tools ModelSim offers numerous tools for debugging and analyzing your design. 1. Setting breakpoints and stepping through the source code 2. Viewing waveforms and measuring time 3. Viewing and initializing memories

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