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International audience; This vulgarization article contains a brief and intuitive workflow for object extraction starting from the input image until the final results are obtained.

International audience; Markov Random Fields in Image Segmentation provides an introduction to the fundamentals of Markovian modeling in image segmentation as well as a brief overview of recent advances in the field. Segmentation is formulated within an image labeling framework, where the prob- lem is reduced to assigning labels to pixels. In a probabilistic approach, label dependencies are modeled by Markov random fields (MRF) and an optimal labeling is determined by Bayes- ian estimation, in particular maximum a posteriori (MAP) estimation. The main advantage of MRF models is that prior information can be imposed locally through clique potentials. MRF models usually yield a non-convex energy function. The minimization of this function is crucial in order to find the most likely segmentation according to the MRF model. Classical optimiza- tion algorithms including simulated annealing and deterministic relaxation are treated along with more recent graph cut-based algorithms. The primary goal of this monograph is to demonstrate the basic steps to construct an eas- ily applicable MRF segmentation model and further develop its multi-scale and hierarchical implementations as well as their combination in a multilayer model. Representative exam- ples from remote sensing and biological imaging are analyzed in full detail to illustrate the applicability of these MRF models.

International audience; Marked point processes have proven their efficiency in solving object extraction problems from high resolution optical images. However, these complex mathematical models are difficult to simulate which usually results in high computation times. A new parallel sampler has been recently developed. Nevertheless, this sampler does not yield good results in the presence of large objects. We propose modifications to the original parallel sampler to cope with such situations. Furthermore, we implement an additional mask to increase the speedup in the case of boat extraction.