In this paper, we studied the association of random infrared thermography, Singular Value Decomposition (SVD) and Higher Order Statistics (HOS) to help to restore works of art. We present first, the principle of theses signal processing methods. We show then, that this association allows detection of inclusions of plastazote located in an academic fresco. We show in a third stage that this photothermal method permits the location of defect located in a real work of art. It is the painting on canvas entitled "Saint Martin" located in the church of "Bonnet". Finally, we show that this association permits in one hand the use of a lower power density. On the other hand, it permits to reduce the influence of radiative properties of the pictorial layer and of the inhomogeneous energy deposition on the photothermal signal.