If you look at the sky in this HDR picture of Sacre Coeur in Paris, you can see strange and unnatural patterns in the clouds. This occured because during the fairly long exposures that went into making up the bracketed images for the HDR process, the clouds moved. This is a composite of five images, and when the software put the images together, the cloud pattern was a little different in each shot.
What is the solution here? There is only one possibility. I would have had to take another cloud image in a single exposure, one where the clouds are exactly the exposure I wanted, and then I would use Photoshop to replace the sky entirely. The reason I wanted to do HDR here was to have detail in the trees. With a single exposure, they would have been black silhouettes.
I used Nik Software's HDR Efex Pro 2 to make this composite image.