Atlanta (www.imagine-your-world.com): HDR, which stands for High Dynamic Range, has become a buzz-word in digital photography. Basically, HDR is a technique that allows photographers to capture images with a greater dynamic range between the lightest and the darkest part of an image. The dynamic range is usually described as Exposure Value (EV), a measurement that denotes to a combination of aperture and shutter speed. While composing an image, photographer can choose different camera settings and still end up with a perfectly exposed picture until the dynamic range becomes too high for the sensor.
This is where HDR comes into play. Multiple pictures of the same object are taken using a tripod, a remote release, and mirror lockup to avoid any camera movement. One picture is exposed to capture the highlights, the next focuses on the midtones, and another one captures the detail in the shadows. The cameras sensor resolution, noise, and gamma curves, among other factors, have an effect on the outcome.
Some cameras incorporate a feature called bracketing (AEB) that allows photographers to take several successive shots of the same object with slightly different predefined exposure settings. The resulting images are combined in post processing to create a high dynamic range image. Several software packages including Photoshop HDR Pro, HDRSoft's Photomatrix Pro, and Nik Software's HDR Efex Pro can be used to combine and process the pictures.
The roots of HDR can be traced back to Jean-Baptiste Gustave Le Gray (1820 to 1884.) The French photographer pioneered the use of several exposures to fix extreme luminance ranges. Le Gray combined two negatives exposed for the highlights and shadows in a single positive. 100 years later, American photographer Charles Wales Wyckoff made headlines when his pictures of a nuclear explosion appeared on the cover of Life magazine. Dodging and burning was famous in the 1950s and 1960s, and Ansel Adams manipulated many of his famous shoots in the darkroom using the two techniques.
Digital cameras and readily available computer processing power have contributed to the rise of HDR in recent years. Today, more and more photographers experiment with different kinds of bracketing. Focus, depth of field (DoF), and white balance bracketing are used to overcome technological limitations. If used correctly, the resulting images can be stunning.
American photographer Ansel Adams perfected the use of dodging and burning in the darkroom. It took a couple decades before widely available computer processing power and digital cameras allowed more and more photographers to experiment with different forms of bracketing and HDR.