<p>The concept of digital manufacturing assumes an application of digital technologies in the whole product life cycle. CAD product model replaced engineering drawing in digital manufacturing. In contemporary practice the engineering paper-based drawings are still archived. They could be digitalized and stored to one of the raster graphics format. After that they could be vectorized for interactive editing in the specific software system or for archiving in some of standard vector graphics file format. The vector format is suitable for 3D model generating too. The article deals with using of methods for preprocessing phase of digitalized engineering drawings vectorization process.</p>