In past centuries, to prevent exquisite paintings, new works of art were painted on them. To identify the hidden paintings on the board, using digital radiography as a non-destructive testing method is recommended. Some phenomenon such as photon scattering, different types of noises, etc. causes on the quality of output radiographs. In this paper, we use two pyramid-based techniques, i.e., the Gaussian pyramid method and the Laplacian pyramid method, to improve the quality of radiographs. The experimental results show the effectiveness of applied techniques for identifying the hidden paintings.