High Dynamic Range (HDR): A Useful Photographic Tool

There is some controversy about using HDR. This stems from the presentation of some HDR images done badly and the somewhat difficult processing of the image for the average photographer to get the desired results.

sunset hdr

Photo by Justin Kern.

The human eye can adjust to deep shadows and overly bright light quite quickly. The perception of the total image includes information from the deep shadows as well as detail from the bright highlights. We have been somewhat spoiled in the past using negative color film for our daily pictures. This method uses the adjustments from the camera’s original exposure and the exposure adjustments in the printing process to compress the wide band of detail into a viewable photograph. Along with this process comes a loss of detail in both the shadows and the highlights. Slide film like Kodachrome had a wider dynamic range but was less forgiving in producing a perfect exposure. Digital cameras have a similar characteristic.

In the early years of photography the problem of dynamic range (the lack of) was solved by photographers like Ansel Adams several ways. He used silver based negative glass plates which had a decent dynamic range. The printing paper could not display nearly as much detail as was available on the negative. This was solved quite well by using a printing box with a couple of dozen small lamps which could be switched on or off individually. This manipulation supplied less light for the shadows and more to the highlights to produce a print that displayed detail in both areas. Contrast was controlled by warming the chemicals in the shadows and diluting the chemicals in the highlights. In the 1970s I used variable contrast printing paper to achieve similar results. I held back the shadows with a violet filter, lightening the dark areas while increasing the contrast to a viewable level. The highlights I burned in with a yellow filter in order to print down the overexposed highlights without raising the contrast unduly. Of course, this only worked with black and white photography.

zen garden

Photo by Thomas Smart.

Other methods that can be used are light painting (shining a moving spotlight on dark areas with the shutter open), using extra strong lights for dark areas and using gobos (movable shades) to hide light for very light toned areas. Commonly open flash on the camera is extensively used to open up shadows. Unfortunately, this presents a very flat light source, diminishing the beauty of light modelling.

In today’s digital world, a digital camera acts similarly to the old Kodachrome in respect to dynamic range. Overexposed highlights like a bright sky simply burns out, displaying a pure white in the photograph. All cloud and sky detail is missing. In underexposed shadows contrast is low and much detail is lost in the dark murk. Additional overall exposure would help the shadow detail but would make the highlights even more blown out. HDR solves this problem, at least with non moving subjects, by combining the information from three or more images photographed in increasing steps of exposure. If there is plenty of light, some digital cameras can take three photographs at differing exposures quick enough to prevent blurring without using a tripod. The best information from the highly exposed images is combined in the computer with the well balanced information from the properly exposed highlight areas to produce a photograph that displays all the information you can see with your eyes.

hdr tips and tricks

Photo by Harry Pammer.

HDR software is available from several sources costing from between fifty and one hundred dollars. Advanced computer buffs can take advantage of their DSLRs with their RAW capabilities and high resolution numbers to create beautiful landscapes and portraits. I envision future digital cameras with built-in HDR capability. They already can take three to five images at graded exposure steps. All that is needed is the HDR software. Presently I am experimenting with Dynamic Photo HDR and find it fairly easy to learn. The key seems to be paying attention to creating the proper range of exposures to get the desired results. Many other artistic tools can be applied the HDR image like brushwork, highlight enhancement and increased color saturation. Like anything else, initial enthusiasm for HDR can lead to the overuse of the process, leading to unnatural looking photographs. Just as in life, moderation is key to using the tool of HDR to create beautiful photographs.

About the Author:
Kenneth Hoffman is a retired portrait and wedding photographer, he enjoys writing, how to articles, helpful articles on photography and many other subjects. His hobbies include quartet singing, shop, bicycling and photography. You can find him at photoartbyken.com and redbubble.com under webster7.

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Article from: PictureCorrect


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