Cool, yes. Real, no.
Here’s how. This works for both GIMP and Photoshop.
- Select the sky and feather the selection a little. In Photohop, using a Quick Mask and a black->white gradient works best.
- Select Curves. Pull the middle to the top and both end points to the bottom to get a bell curve like an upturned U.
- Admire your handiwork
This one was done in GIMP. I also used the Lomo script to vignette the corners.