Fair-faced concrete elements have become even more popular in architecture because of their pure aesthetics and favourable material properties. The europian standards and guidelines are usually specifying four classes regarding to the surface quality. However, the strandard assessment methodologies are based only on manual methods and they are very subjective in some cases. In order to increase the efficiency and accuary of the evaluation a new methodology is proposed using digital image processing. In this paper the basis of the evaluation method made by using the Python 3.6 software is presented by focusing on the surface void ratio which is one of the most common surface defects of fair-faced concrete structures.