  Method for a mosaic image representation (MIR) is proposed for a selective
treatment of image fragments of different transition frequency. MIR method is
based on piecewise-constant image approximation on a non-uniform orthogonal
grid constructed by the following recurrent multigrid algorithm. A sequence of
nested uniform grids is built, such that each cell of a current grid is
subdivided into four smaller cells for the next grid designing. In each grid
the cells are selected, where the color intensity function can be approximated
by its average value with a given precision (thereafter 'good' cells). After
replacing colors of good cells by their approximating constants the
reconstructed image looks like a mosaic composed of one-colored cells.
Multigrid algorithm results in the stratification of the image space into
regions of different transition frequency. Sizes of these regions depend on the
few tuning precision parameters that characterizes adaptability of the method
to the image fragments of different non-homogeneity degree. The method is found
efficient for prominent contour (skeleton) extraction, edge detection as well
as for the Lossy Compression of single images and video sequence of images.
