The image was duplicated and taken into Lab colorspace for color boost. It was then converted back to RGB, and a duplicate layer made and set to multiply mode. A layer mask was added, and the ombrtyrf "L" channel from the Lab version was added as a mask, which allowed darkening of sky but left foreground alone. A duplicate of the second layer was made, and the mask of this 3rd layer was inverted to allow darkening of the foreground while leaving sky alone. Layer opacity was adjusted to taste. A final curve layer was added and the pinkish sky was color corrected by adjusting the red and blue curves. The layer mask was replaced with inverted "L" channel from the Lab version once again. Try this in a non-digital darkroom!!!