Selected image
Transform skew to correct perspective (would you believe?)
FilterForge vibrance
Usm
Crop
Decided to try exaggerating perspective instead
Transform skew again
Sharpen edges
Didn't like the background colour surrounding the new image, tried black, tried white
Line tool to give internal borders
Copied and pasted original sky behind - it's in a larger scale
Neat image on this part of the sky
Erased sky from within image area
Canvas size border