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Very High Dynamics Imaging rounds up various techniques that can be used to study the close environment of a source which flux, comparatively very large, prevents to see the morphological features immediately neighbouring the source. Several instrumental approaches have been devised in this purpose, among which apodisation, mask coronagraphy and nulling techniques. In view of applying them to various scientific programs, both shared constraints and specific features of the approaches have to be identified. This is the subject of this paper, which also recalls basics principles. A new concept (EvWaCo) achieving coronagraphy by using evanescent waves is briefly outlined.