General Compression Concepts

Why do we need compression?

Have you ever tried to pack your car for the summer holiday?

Organizing the space in the car could be compared to the data compression problem. Large amounts of data can create enormous problems in storage space and transmission time.

The main reasons of data compression could be summarised as:

Multimedia data have large data volume
Difficulty sending real-time uncompressed data over current network

The widespread consumer-market use of information in the form of images has contributed much to the development of data compression techniques. The design goal of image compression is to represent images with as few bits as possible, according to some fidelity criterion, to save storage and transmission channel capacity.

Compression data principle

“Eliminate data redundancy and try to find a code with less data volume.”

All image compression techniques try to get rid of the inherent redundancy, which may be spatial (neighboring similarity or equal pixels), spectral (pixels in different spectral bands in a color image) or temporal (correlated images in a sequence, e.g. television).