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New technique based on continuous wavelet transform (CWT) for classifying objects in synthetic aperture radar (SAR) imaging is presented. The CWT allows to analyse two-dimensional SAR images to highlight the frequency and angular behaviour of the scatterers ref. 10, 11. This technique allows to build a SAR hyperimage, that is, a four-dimensional data cube which represents for each spatial location (x, y) of the scatterer in the image, its frequency and angular energy behaviour. When analysing different targets, objects or areas in SAR images, it has been recently observed that some scatterers belonging to a same class of objects could have similar frequency and angular energy responses. The previous observations have motivated the determination to exploit these energy responses to discriminate these objects. This discrimination is performed by frequency and angular correlations between the response of a particular scatterer (measured) and those of all the scatterers in the SAR image. Some examples of discrimination from real SAR data are presented and show an interest of the method for target classification and recognition for SAR imaging.

International audience; As a time-frequency tool, the Continuous Wavelet Transform (CWT) was applied in radar imaging to reveal that the reflectors' response varies as a function of frequency f and aspect angle θ (orientation of the wave vector). To do so, we constructed a hyperimage expressed as the squared modulus of the wavelet coefficients, allowing to access to the energy distribution of each reflector, in the f − θ plane. Exploiting the hyperimage, our recent researches were devoted to the classification of the reflectors in function of theirs energy distributions with the objective of discriminating a type of target in the radar image. Althought acceptable results were obtained, the method is not reliable in some cases. The purpose of this paper is to show that exploiting not only the modulus but also the argument of the wavelet coefficients, can improve the detection of a certain class of reflectors. Results are presented at the end of this article.