Numerical characterization of surfaces with deep dimples, e.g. Laser Textured Surfaces, poses questions relative to the standard filtering techniques used to separate roughness, waviness and form effects. Usual roughness filters would produce a reference plane several micrometers “below” the surface. If this surface plane will be used as reference for mixed lubrication modeling, no hydro dynamic pressures and excessive high contact pressures may be calculated.The conventional roughness filters, Gaussian and Rk, and 4 other filters were applied in an artificially dimpled surface in order to demonstrate and especially to discuss how the Greenwood contact parameters were affected. Depending on the filter used, the estimation of the minimum surface separation for asperity contact varied two magnitude orders. The high surface separation predicted using the parameters calculated by the usual filters would result that no hydrodynamic support would be predicted by the mixed lubrication models. For input on models of mixed lubrication, the mode based filters appeared to be recommended.