The picture on left is the original and the final output is the right one. I am very curious how to make the entire background blue?
Boost the exposure and correct the color temperature. Saturate to taste.
Thanks for the quick response.
Maybe balance on the umbrella somewhere.Could be a touch of tonemapping or contrast bump - hard to tell for sure with a small thumbnail.
If the above don't work you could use a parametric mask in the colour correction module to shift everything in the hue and lightness of the sky to the colour you're after. It worked for me changing some brown water to a more pleasant blue-green.
Looks like it might have been done with the color mapping module:
Play with channel mixer also