This thesis presents new methods for spherical Poisson data analysis for the Fermi mission. Fermi main scientiﬁcal objectives, the study of diﬀuse galactic background et the building of the source catalog, are complicated by the weakness of photon ﬂux and the point spread function of the instrument. This thesis proposes a new multi-scale representation for Poisson data on the sphere, the Multi-Scale Variance Stabilizing Transform on the Sphere (MS-VSTS), consisting in the combination of a spherical multi-scale transform (wavelets, curvelets) with a variance stabilizing transform (VST). This method is applied to mono- and multichannel Poisson noise removal, missing data interpolation, background extraction and multichannel deconvolution. Finally, this thesis deals with the problem of component separation using sparse representations (template ﬁtting ).
Multichannel deconvolution and source detection using sparse representations : application to Fermi project