This part was the “twist” ending to the scene. In this process, there did several important steps that dressed the scene.
The common elements for both images were added as birds flying, or background + sky, obviously in this case, should be different, as the highlights.
Despite working all 3d vegetation through proxies, we finally decided to replace it with a background of snow covered trees in both cases.
Small elements were inserted also little noticeable, but they are, as the fog was added at some points and colored the snow in others, the tree sticking out of the top mixed with existing small details that embellished the scene .
There are many alternatives retouching in this process, many options, many tools used.
We used different programs and combine their results.
They touched exposure values, brightness, contrast, hue, saturation, levels, color balance, cromatic aberration, vignette, focus, blur … and the end result is already known.
Some screenshots of post-production process: