The present disclosure describes one or more embodiments of a selective raster image transformation system that quickly and efficiently generates enhanced digital images by selectively transforming edges in raster images to vector drawing segments. In particular, the selective raster image transformation system efficiently utilizes a content-aware, selective approach to identify, display, and transform selected edges of a raster image to a vector drawing segment based on sparse user interactions. In addition, the selective raster image transformation system employs a prioritized pixel line stepping algorithm to generate and provide pixel lines for selective edges of a raster image in real time, even on portable client devices.