Some time ago, out of boredom, I vectorized some pictures by manually tracing them with the Pen Tool with Photoshop. It was a painstaking process, taking some two to three hours to finish, depending on detail. Inkscape is a vector graphics application. It creates artworks with scalable vector graphics (SVG). This format allows you to resize the artwork without having to deal with scaling issues or rasterizations. However, SVG is not designed to work on photos, as it is not a raster based format.
Inkscape has a feature I found interesting: tracing bitmaps. It takes a picture, applies an algorithm on detecting parts of a picture (usually edges, large patches of color, etc.) and tries to make it into a vector. Of course, being a vector format it is, it cannot recreate photorealistic pictures (could be possible, but the requirements to render it would be unreasonable), but it did do one thing I had wanted to do: vectorize pictures.
Without further ado, here are some artworks that were made with Inkscape’s trace bitmap function.
All these pictures were based from real images.
These works are under Creative Commons 4.0 or later BY-SA