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The world of design is teeming with a myriad of techniques, processes and technologies. One such technique that I recently became aware of is HDR (High Dynamic Range) photography. Now, HDR is not a new process — it dates back to the 1930’s, but it has in recent years become more popular in creating photographic images with an extremely high tonal range.

Originally used in 3D, HDRI (High Dynamic Range Imaging) is now in popular use in photography. At it’s most basic level it is the process of taking multiple exposures and merging them together into a single 32-bit image — normal photographs have an 8- to 16-bit depth.

The human eye can see a larger range of tones than the camera can capture on the chip or film in a single photograph. Typically, we must sacrifice elements in a photo when we press the shutter. The solution is to take more than one photograph using a technique called bracketing — shooting a photo at normal exposure, then under-expose a shot to capture highlights and over-expose a shot to capture shadow detail.

FIGURE 1: An Example of Bracketed Exposures

HDR allows a photographer to capture difficult shooting situations such as a powerful cloudscape and some cliffs. With traditional photography, if the clouds are properly exposed then the cliffs become dark. If exposure is set to capture detail in the cliffs, the brighter sky is blown out and detail is lost.

By taking a bracketed set of photos of the scene and then using the HDR tools found in the latest versions (CS2 and CS3) of Adobe’s Photoshop, a photographer is able to merge the photos to produce a single image with the larger range of tones that are required to show all the details in the shadows and highlights.

The Sydney Harbor Bridge from Kirribilli at night