AN INTEGRATED COMPRESSION TOOLKIT FOR GRAPHICS, AUDIO AND TEXT

Abstract

Data compression is the process of eliminating or reducing the redundancy in data representation in order to achieve savings in storage and communication costs. The use of multimedia focuses the issue of data compression. Computer graphics in particular quickly take up all available disk space. Digitized audio is far less voracious in its storage requirements, but even so it quickly swallow up all free space. In the 'dissertation, a compression toolkit for the three services graphics, audio and text have been implemented and integrated. The graphics compression scheme uses variable block size segmentation technique, the speech compression scheme uses companding technique and the text compression scheme uses Huffman coding. Image compression is achieved by segmenting an image into regions of different sizes, classifying each region into one of several distinct categories and using a distinct coding procedure for each category. Speech compression is achieved by transforming codes to voltages by using an exponential function that changes the sizes of the voltage step between codes. The compression ratio obtained on all test images are above 70%, while on sound files, it has been fixed to be 50%. For text files, compression ratio is around 40%. All work, has been done on Silicon Graphics Workstation "Indy" under IRIX 5.3 operating system environment.