HDR (High Dynamic Range) photography refers to increasing the color range of a photo.
Our eyes are an amazing contraption. They quickly adapt to many lighting conditions, and the brain kicks in whenever help is needed. In certain conditions, your camera will fail dramatically (or just fail, depends how you look at it), be it a camera mounted on a spy pen or a new Canon 5D Mark II. The conditions I’m referring to are ones which include very bright and very dark areas. Correct exposure to the dark areas will burn the bright areas, correct expose to the bright areas will result in very grim dark areas.
Consider the following photos of average exposure, correct exposure to bright areas and correct exposure to dark areas:
 People's Park, Shanghai - EV 0 |
 People's Park, Shanghai - EV -2 |
 People's Park, Shanghai - EV +2 |
So what do we do? We take multiple shots with EV compensation! The photos above were taken at aperture priority with an aperture of f/16. The first image shutter speed determined by the camera for correct exposure: 1/640 seconds (high ISO used). For the underexposed image, the shutter speed went up to 1/2500 seconds (-2 means 2 stops under, so multiplied by 4). The overexposed image’s shutter speed was 1/160 seconds. Notice how the first photo is nice, but it loses details which are found in the other 2 photos (at a cost of ruining the remaining details of the image).
Next, we combine the photos into a single picture, by taking the correctly exposed areas from each photo. You can do it in Photoshop (many tutorials online) or use a program doing that thing exactly. I achieved the following result using the trial version of Photomatix (so forgive the watermark):
People's Park, Shanghai - HDR
Detailed building from the underexposed photo, details in the tree and water from the overexposed photo.
Check your camera user manual, usually it will offer you an auto-bracketing feature, which will take a normal photo when you first release the shutter, an underexposed on the second release and an overexposed on the third. You can also determine by how much do you want the EV compensation to be. By the way, using a tripod is recommended.