One post-rendering technique used for still images in 3D visualization is to overlay an ambient occlusion layer to deepen the shadow spectrum created by global illumination.
That was the general approach here, but rather than using an AO layer on a CG rendering, I used several instances of the same photo at varying grayscale and opacity levels with a few different solid colored multiply layers and finally a number of subtle adjustments to brightness, contrast, hue and saturation.
Why? Sometimes we just have to play.
Taken at the Ca'dZan in Sarasota, the original photograph by Brock is available for viewing at ElectricSynapse.com in the Photography section of his online gallery.
The alterations were completed in Photoshop CS2.