This paper exposes a method for evaluating the performances of a system dedicated to exoplanet direct imaging. It is based on the use of a statistical description of a somewhat ideal star/planet couple in terms of contrast and angular separation. Among many already available techniques, the Phase Induced Amplitude Apodization Coronagraph (PIAAC) seems to gather all the necessary qualities to perform direct imaging of hypothetical Earth-like exoplanets in the close Solar neighbourhood (30 pc). After a quick description of its concept, the proposed evaluation method is used and provides an original set of criteria to classify concepts.