Problem: Would like to create a HDR image, but only have a single exposure and its a JPG file.
Solution: As programs like Adobe Camera RAW support also JPG files you can take your JPG photo and split it into different exposures. Just create three copies, one with -2EV, one at 0 and one at +2EV. From here the process is exactly same as if you taken three separate photos.
I use this usually when I edit older photos, taken before I started with HDR photography. The results are mixed. Sometimes this really helps a photograph, sometimes it doesn’t.
Night by the Lake
I really like my camera (Canon 450D) but it’s really not that great for night shots. Still sometimes I’m really pleased with the result. HDR from three shots, taken with Canon 450D with Sigma 18-200mm lens from a tripod.
I pushed this one quite a bit. I quite like the halo like effect which is around the plane as it distances it nicely from the background. HDR from three shots, taken with Canon 450D with Sigma 10-20mm lens from a tripod. Photo taken at the Death Valley in Slovakia.