HDR

An HDR (High Dynamic Range) image is a digital image, which displays large differences in brightness with high detail. These HDR images are capable of displaying a wider range of contrast than is possible with normal images (so-called low dynamic range images).

The 256 brightness levels commonly used are usually not sufficient enough to be able to reproduce the actual differences in brightness that appear in nature. HDR images attempt to bring the dynamic range of the digital camera closer to that of the human eye. Unfortunately, the displays of most devices as well as printed media are not able to correctly display this. Nevertheless, LDR images can be generated from the HDR images (which are necessary for their portrayal), which reflect a significantly higher amount of detail.

Generating HDR Images

There are several ways to generate HDR images. Some special cameras are capable of displaying a noticeably higher dynamic range than common digital cameras. New developments in technology have even surpassed the sensitivity and dynamic range of the human eye. With prices around $50,000, these special devices are hardly affordable for the common consumer and reserved for professional applications.

For photography amateurs, however, there is the creation of exposure bracketing. Using this method, three different exposed images of a motif are combined into one HDR image by using special software. In the original images, each area of the image must be correctly exposed at least once. One difficulty photographers run into when using this method is moving objects. Thus, camera shake should be avoided from the get-go when taking the original photos. It might be a good idea to use a tripod in this case.

Many high-quality digital cameras (and some inexpensive compact cameras) are currently capable of generating an HDR image from several individual images. To do this, you just need to switch on the HDR function on your camera. This function operates just as the method we described above: several individual images with different exposures are taken by the camera’s processor and combined into a single HDR image.

A third possible method of creating HDR photos is to render them by using 3D software on a computer. This technique is mostly used in computer games where players often switch between environments that are very dark and very bright.