WA VELET-DCT BASED IMAGE CODER FOR VIDEO CODING APPLICATIONS

Utilization of digital video raises important concern on storage space and
transmission purpose. A video codec that compresses digital video signal has
become an essential component in video application.
The interest of this project is to integrate a wavelet-based compression and at
the same time providing a backward compatibility to the existing architecture of
MPEG-2 standard. Wavelet-DCT is an algorithm that utilizes Discrete Wavelet
Transform (DWT) to compute Discrete Cosine Transform (DCT) coefficients. The
algorithm allows truncation of intermediate coefficient through DWT. This process
is also known as thresholding. The Wavelet-DCT algorithm is integrated into a
simulation of intra-frame coder in compliance with MPEG-2 standard. To enhance
the system performance, threshold level selection is done via histogram energy
analysis and selection of best wavelet type through statistical study.
The simulation was developed using SIMULINK and MATLAB. WaveletDCT
based intra-frame coder was simulated by employing two different approaches.
Different types of multimedia source (image and video) were tested on the
simulation.
The result from both approaches for images shows marginal improvement at
higher compression ratio. On the other hand, when it was tested on video, which
consists of different types of images, both approaches does not show a reasonable
improvement at various level of compression ratio.
The argument on why wavelet-DCT based intra-frame coder does not
perform better arises from the objective's restriction that attempts to cater the
backward compatibility. Some recommended areas to be delved for future work on
video compression are distributed video coding, ridgelet transform and dual-tree
complex wavelet transform.