High Dynamic Range Photos
A digital camera’s sensor has a more limited dynamic range than the human eye. This means that if you expose a photo for the bright areas, the camera may not “see” details in the dark area that your eye can see. Likewise, if you expose a photo for the shadows, the camera may not “see” details in the bright areas. This makes it difficult to capture a photo of what you see.
High Dynamic Range (HDR) imaging techniques take a series of normal (or Low Dynamic Range) photos and merge them together to form a single HDR photo. Now it is possible for the photo to show details in both the bright and the dark areas. Depending on the light in the scene, you may want to capture multiple shots; for example, it is not uncommon to merge up to five (or even more) photos.
Qtpfsgui [via gHacks] is an open-source program for generating high dynamic range (HDR) photos. It is free, and available for Windows, Linux, and Mac.
Photomatix is a commercial HDR program for both Windows and Mac. The basic version, however, is free to use.
Photoshop CS3 is certainly not free, but it has HDR support.
HDR imaging is fun to try. Many HDR images tend have unrealistic colors. However, HDR imaging is also able to produce amazing photos.
There are a number of excellent HDR tutorials available online.