Gottfried Hofmann from the BlenderDiplom shows how you can recreate the “Sin City” look in Blender using the Blender Compositor, some tracking and rotoscoping.

If you want to apply the Sin City look to your footage, Blender now has all the required tools at hand. This tutorial shows you how to do it using the compositor and the tracking- and masking-tools

Gottfried shows how to create a black and white look while still maintaining some color areas in the footage, using the Hue Correct Node in Blender to selectively desaturate the image, and masks to narrow the color corrected areas. Check out the tutorial for ReCreating a Sin City Look in Blender here.