Colour Image Coding by Visually Meaningful Image Patterns

Visually meaningful patterns (visual patterns) are a set of predefined image blocks representing information the human visual system is very sensitive to. A colour image coding technique based on visual patterns is introduced. An image is divided into small blocks each of which is mapped to one of the visual patterns. Each block can then be represented by the pattern and by the colour information of that block. Colour quantisation and entropy coding are applied to achieve efficient coding. High compression ratios (35: 1 70: 1) have been achieved while maintaining good image quality, comparable to that of state-of-the-art techniques such as PEG. In addition, the encoded images can be used in their compressed state in content based image retrieval systems based on colour and shape features.