CS3242 – Hypermedia Information Processing

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Introduction
This project is to develop a program that implements a simple hierarchical JPEG
encoder/decoder for greyscale images.
JPEG still picture compression standard is one of the most popularly used formats for
digital images storage and interchange. The JPEG (Joint Photographic Experts Group)
format was established in 1986 and adopted as standard by ISO/CCITT in 1991.



System Design
The whole system was designed with the hierarchical JPEG operational flowchart in
mind. However, for the ease of implementation, I decided to simplify the actual
compressed file format as well as part of the internal data flows. (I call the simplified

JPEG file format “vJPG”.



System Implementation
The GIF2vJPG system is implemented purely in the JAVA programming langauage, in
favour of JAVA’s portability, its rich data structure library and its flexible object-oriented
programming style.
For the ease of black box implementation, I defined a few interfaces and abstract classes
to specify the external views of different blocks in the system:


Conclusion
I implemented a pair of simplified hierarchical JPEG encoder and decoder, GIF2vJPG.
The system can perform multiple levels of hierarchical JPEG encoding/decoding with
variable quantization scalars.