High Dynamic Range (HDR) is a technique that is used to produce a final image that has been generated by three or more different exposures of the same subject that are subsequently merged together using specialized software. The concept of using different exposures to produce a final image is not new, as shown in the work of Gustave Le Gray, who produced an image ‘The Brig’, from two exposures in 1856. Also an American photographer called Charles Wyckoff, captured the detonation of the first hydrogen bomb, using multiple exposures from a film he developed in 1954.
As time moved on with more research into digital imaging being undertaken, techniques became more sophisticated, including those applied to HDR. In 1985 a Software Consultant and Contractor called Greg Ward created the radiance RGBE file format for HDR images which is still in use today. In 1993, Steve Mann an American Professor working at the University of Toronto, reported creating a tone mapped image from a sequence of exposures of normal digital images. He shot a sequence of exposures that covered the full brightness range of the image, and combined them into a single, high dynamic range picture that would contain detail in everything from the brightest highlight to the deepest, darkest shadow.
The technique as used today involves taking three photographs of the subject, the metered exposure and then two stops over exposed and two stop under exposed. Most modern DSLR cameras can be programmed to take the three different exposures, ideally by setting the camera to make the different exposures by altering the shutter speed rather than the aperture settings. The images can then be downloaded into a software program such as Photomatix or into Photoshop, for the images to be merged together, enabling the best features of each exposure to be exploited to produce the final image. When the image has been downloaded into the software there are many opportunities available to further enhance the result such as tone mapping and exposure fusion. A free trial of the software is available for use so that investigations into various image enhancements can be explored when the three exposures have been merged together. A free trial of Photomatix can be downloaded, www.hdrsoft.com/download.html, to create HDR images, including the various enhancements contained in the package to gain the desired result.
Another way of merging the three exposures to gain a realistic looking HDR image is to use Photoshop. Select the three images then download them into ’Photomerge Exposure Merge’ which is found in Photoshop Elements. There are opportunities for further enhancements when the images have been merged, but not to the same extent as with Photomatix.
I would be interested to hear from members who have tried this technique in their work or from members who may try it in the future.
Contact e-mail address: K893@btinternet.com
References
Google Searches
- Gustave Le Gray Google
- JP Getty Collection
- Front Covers Life Magazine
- Photomatix
- Charles Wyckoff, Photo Expert SunSentinel site
- ‘what is HDR photography?/ then and now’ / Enlight App
- hdrsoft.com/download.html
Practical HDR (second edition) – A complete guide to creating High Dynamic Range images with your digital SLR by David Nightingale