Scratch resistance of filled polypropylene (TPO) plays a central role in its suitability for automobile interior components. The quantitative characterization of surface scratches is therefore essential. In this work, TPO test plaques have been subjected to controlled scratch deformation by the use of a new computer-controlled laboratory test apparatus. The visual appearance of the scratches has been assessed by means of scanner imaging and standard image analysis software. Parameters have been found to express quantitatively the visibility of scratches and its dependence on scratching load and speed.