Segmentation to diminish the mosaic effect

In block coding techniques a harmful effect is the gap between blocks. The mosaic effect is important in smooth areas. In block coding techniques, the subjective quality depends on the mosaic effect. Among regions and on edge zones the mosaic effect is less injurious than in smooth areas. If the difference between blocks coincides with contour areas the visual effect almost disappears. The objective is to select a block with contour boundaries. Then another problem appears. It is not possible to select a regular block that matches exactly with an image region. On the other hand, the coding method will be modified to use irregular blocks. A large zone segmentation provides a uniform characteristic region. The boundaries of these regions will be edge areas. There are several methods of segmentation. We test statistical and morphological methods. We allow slow variation of the selected characteristics within every region. Segmentation coding methods use small regions and store their average gray level. Our method stores the most suitable characteristics for every large region. Sometimes the region will be expanded to a regular zone to use transform coding, such as DCT.