A new approach to characterize the roughness of paper in contact with ink under compression in the printing nip is proposed. The printing roughness is calculated from the parameters of the ink coverage function contained in the ink transfer equations. The approach assumes an identity between the ink transfer coverage function and the pore shape function of the surface pores. Although the printing roughness correlates well with standard roughness/porosity tests, different regression lines result from different printing conditions . The printing roughness was found to be inversely linearly related to the logarithm of the printing pressure with the slope of the regression line representing a measure of the compressibility of the paper surface. The compressibility is independent of the printing pressure but, for rough papers, is a function of the nip dwell time.