Abstract : Very high resolution images, such as airborne images,
are full of very interesting details for scene analysis. However, generally,
full resolution is not required on a whole scene and only a few areas of
interest, as well as structuring cartographic features need it. Thus, having
a multiresolution image with some parts at full resolution and others at
coarser resolution is sufficient for many applications. Moreover, such
images offer some interesting characteristics. Such images, combining different
resolutions can be obtained by adaptive filtering of images at high resolution.
We propose three methods of adaptive filtering that smooth an image while
preserving cartographic structuring features or interesting regions of
the image. The first one relies on an anisotropic diffusion method introduced
by Saint-Marc, Chen and Medioni. The second is based on wavelet theory.
Eventually, the third method is based on an analogy between the image and
an electrical network. Each node of the network (i.e. pixel) is connected
to his neighbours by means of resistors. Some resistors are representative
of the diffusion and others of the importance of the original data in theiffusion.
In that purpose, we study the relations between parameters of
the network and the resolution of the filtered image and we demonstrate
the links between electrical analogy and a Markov s approach. We estimate
and compare these methods underlining advantages and limits of each one.
From these methods, we propose two applications : the generation of an
adaptive quick-look and adaptive compression. Concerning the first application,
we propose a method to generate a subsampled image at low resolution preserving
cartographic features designed as areas of interest by user. Concerning
the second application, our goal is to transmit optimally on a low rate
network an image preserving some cartographic features at high resolution
in a low resolution environment. Thus, adaptive compression links some
classical methods of compression with multiresolution techniques. All these
theoretical results are experimentally checked and some images of diffusion,
quick-look and compression are shown in this manuscript.
Keywords : Multiresolution analysis, Anisotropic diffusion, Quick-Look,
Adaptive and selective compression.