Aftershock, my thesis, is set in 1906. As a horror period piece, i wanted to get a sepia-tone look to the piece, as well as a bit of film grain. Valve’s Left 4 Dead blog post about filmic effects gave me some ideas about how to apply film grain in an appealing way.
I also wanted to fade middle ground elements for some atmospheric perspective, and give bright light areas on screen (such as some of the brighter windows and the streetlights) very hot brightness. All of this, I felt, would add to the heavy, dark feeling of the piece. Very distant elements, such as the sky and the hills across the bay, I wanted to keep visible to prevent it from feeling like a murky fog.
Here i find the dark areas of the scene to which I will apply noise. It is simply the scene, desaturated, with some math performed on it to control where the noise goes.
In the next step I isolate the very bright points of light in the scene. these will be re-added to the scene both to remove any noise from those regions, and to intensify their brightness, adding to the contrast of the final piece.
I next use the scene depth to add more dark areas to my darkness map. Since I have darkened the middle ground, it will now have film grain applied to it. This image will be used as the final alpha to interpolate between the color adjusted scene and the film grain texture.
Color and Fog:
Here once again we have the base scene texture. In this section I will be color grading the scene and applying a dark color to the middle ground.
This is the scene after it has had the color balance tweaked. It was desaturated slightly and had the reds boosted to give the feel of a sepia-toned film.
This image shows the depth masked scene. It was important that my mask exclude near buildings, include all distant buildings and streets, and largely leave the sky and distant terrain unaffected.