Look, In The Sky.

Feel the cool summer breeze. The wind in your hair. Pushing all four colors gives depth to the shadows, while adding cyan and magenta in the mid-tones creates a cool blue cast that helps to bring out the openness and expansiveness of the photo. For the greatest possible contrast, the upper end of the highlights– the areas with the least dots–were kept open.

Three cool gray colors and a heavy black were applied with four layers. A light highlight, a heavy quarter-tone, a light three-quarter tone and heavy shadow were selected in Color Range. The Blend Modes of all layers were left on Normal.

More info:

Quadtones »
Tonal Range »

Ed #2 Quadtones

Image Credit: Andrew Martin