I am using Adobe Photoshop Elements 4.0 for the Mac - I don't know if it's exactly the same in other versions and for Windows.
Vectoring (or is it vectorization?) is the digital effect seen in the movie
A Scanner Darkly.

Original Photo
Vectored Photo1. Open the photo, and using the Magnetic Lasso tool, select the part of the photo you want to vector.
2. Create a new layer from the copied selection (layer 2).
3. Create a new layer with a solid colour (layer 3).
4. Make the original layer (layer 1) invisible (click the "eye" in the layer window).
5. Make layer 2 the working layer. Use smart blur to "decomplicate" (I made that word up).
6. In the filter menu, under "Artistic" choose "Poster Edges." I find that 1 in all the choice boxes works best, but feel free to play around.
7. Under "Edit" choose "Stroke (Outline) Selection". This adds a thick black line around the outside of the image.
8. Under "Layer Styles" in the layer window, create a drop shadow. Double click the "f" in the layer 2 box to change the shadow width and directionality.
9. Delete layer 3 (the solid colour).
10. Under the Layer menu, choose "Flatten Image."
11. Save as desired name.
Ta da!