The research problem of establishing a correlation between the Joint Roughness Coefficient (JRC) and the roughness parameter Z2 is re-visited in this paper. As in other comparable studies, the first step is to digitize the ten standard JRC profiles. An alternative approach of digitization based on the pixel analysis in Matlab is adopted to obtain the standard JRC profiles. The Z2values of the ten profiles are then calculated based on three sampling intervals (small, medium and large) and compared with the prior published ones. To investigate the effect of the finite profile thickness, a parameter called “rta”, which is the ratio of the mean profile thickness to the profile amplitude, is defined and calculated for each profile. Our studies also reveal that the value of Z2 does not increase monotonically with JRC. The fundamental cause of this local peak is analyzed, which deems to be related to the larger waviness, while a smaller degree of local roughness of profile 5 (JRC 8-10). To take both the local profile roughness and the larger scale waviness into account, a new empirical correlation is developed. The numeric values of the associated fitting parameters are then determined.