At this point in the image adjustment process you may decide that the color of the sky background should be something other then completely neutral. Personally, I like the sky background to be slightly blue. Since we have not set the sky background to be completely black, we can adjust the color of it with curves.

To make a small adjustment to the color of the sky background, I will open the curves dialog and move a midtone adjustment point in the red channel down from 128 to 115. This takes out a little bit of red from the image. Then I will go into the blue channel and move an adjustment point from 128 to 137. This will add some blue to the image. These adjustments are based on personal taste.

Mouse Over Original Image and Curves Dialog       Red Channel Adjustment       Blue Channel Adjustment

Hold your mouse cursor over the image to see a comparison between the image before and after the color adjustment. Hold your mouse cursor over the descriptions below the image to see the individual color channel adjustments.

Note that this is a subtle color adjustment. Since the image has the correct white balance, and the sky background has been neutralized, the colors should be very close to being correct before this step. This color adjustment of the sky background is a final tweak based on personal preference.