Presents a new method for compressing temporal series of SAR images. Well suited to noisy images, the algorithm requires a reference scene used as an input in the description process. This description is achieved through affine transformations, comparable to the ones used in fractal coding but applied here in a non-convergent way. Blocks in the image to be compressed are defined by a non-overlapping recursive partition. They are replaced by blocks taken from the reference image on which affine transformations, containing isometries and grey level adjustments, have been applied. Furthermore, the algorithm can take into consideration regions of interest specifying the local compression quality requested. Comparisons with classical compression algorithm, such as JPEG, EPIC or fractals, showed that the authors' method gives better results especially at high compression rates. This algorithm was applied to a set of RADARSAT images acquired over Antarctica. Those images were compressed at a rate of 0.25 bits per pixel, and brought on an icebreaker via an affordable INMARSAT connection, while still remaining of sufficient quality for ship routing usage. The affine description algorithm proved to be very efficient for local characterization of fine details (such as icebergs, or rivers on ice pack), thanks to the recursive partition used: a quadtree partition upgraded with triangles.
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