The paper describes the surface roughness measurement of spark erosion reference standards by means of digital technique, enabling a comprehensive assessment of roughness parameters. Using digital and Fourier analysis, parameters have been evaluated in terms of density and slope distribution, Abbott curve, power spectrum, auto-correlation functions, etc. The commonly used Ra, Rms and Rt have been calculated as per the ISO standard on the mean line (M) system. The effects of standard ISO-double RC and the suggested phase-corrected filters on the roughness parameters, waviness in particular, have also been discussed.