What is High Dynamic Range Imaging?

High Dynamic Range Imaging, HDRI, or more commonly HDR is an image processing process or technique that allows a greater dynamic range of luminances to be displayed than is possible in normal photography. The technique was first used with film in the 1850s but has become increasing popular in digital photography due the ease with which such the images can now be created.

Why use HDR?

A typical DSLR can handle images with a range of luminance of between 5 and 9 stops (mainly depending on the quality of the camera). In a scene that extends beyond the range of the camera’s sensor, for instance one that contains dark shadows and bright sunlight, some element of detail will have to be lost - either the shadows will be too dark (or totally black) or there will be blown highlights in the sky.

In order to capture all the detail in the scene we can use the HDR approach. To do this we take multiple shots at different exposures (3 is the most common number of exposures to use as most cameras are capable of doing this easily, however combining a greater number of exposures may produce a better quality end result) and combine them using software such as HDRSoft’s Photomatix.

Taking the shots at different exposures allows more detail to be captured - taking a shot at -2EV (2 stops down from the normal exposure) will give us more detail in the sky, taking a shot at +2EV (2 stops up) will pick up more detail in the darker areas of the scene. HDR software is then able to select the correct elements from each of the exposures to produce a composite showing much more detail than would be possible with a single shot.

I am currently writing a more in depth tutorial which deals with creating HDR images, but the meantime here are links to my existing HDR articles

http://www.andystafford.co.uk/creating-a-hdr-image-from-a-single-exposure/

http://www.andystafford.co.uk/winter-tree-and-photomatix/

A selection of my favourite HDR images, a brief tutorial and details of my Photomatix discount code can be found here http://www.andystafford.co.uk/category/hdr-photography/