I would like to give the 'Orange & Teal' look to some pictures using only GIMP. I must remark, the question is specifically restricted to GIMP.
My question is simple but here is some background. 'Orange and Teal', also called 'The Blockbuster Look' is the practice of color grading pictures and movies in a simplified palette where shadows are turned into blue and lights are given an orange tone. Hated by many, it is being abused in Hollywood productions more and more, but as any other technique it also can be used very creatively to achieve kind of a warm sunset look.