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HDR “High Dynamic Range” Imaging is a process of combining multiple photographic exposures into a single photographic image containing higher tonal range than that of a single exposure photograph. Essentially, it’s exactly what you’re used to, only more of it. All the same principles and fundamentals of photography apply, there’s simply a greater range of available exposure information. When processed with the intent of accurate hyperrealism, HDR imaging creates a densely woven image that appears as though you were looking at each and every part of the scene closely with your eyes properly exposed for every area at the same time.
There is a huge amount of HDR photography published online these days. This is an outstanding resource for inspiration, technical tips and a sense of what is possible with the medium. When fi rst testing out the process, try pushing things too far, and then pulling in the reigns as necessary to achieve a balanced image. More highly processed HDR images will tend to take on the look of a painting, or computer rendering, which can be used to
great eff ect, although not ideal for realism or portraits. When realism is the intention, using lower levels of enhancement and blending the HDR composite image back with the single frame original is an easy way to tone down the eff ect. Test the limits of your camera and software package and steadily develop a workfl ow that is optimized for the tools available. The creative and artistic possibilities of the process are as limitless as photography itself.
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Always keep in mind that a good photo is a good photo, while HDR is a series of techniques that will allow for greater enhancement, the technique alone will not produce superior results. The major difference when approaching HDR photography is you’ll know at the time of shooting that traditionally problematic contrast areas will be properly exposed in the final image. This will greatly enable you to create your compositions accordingly.
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GETTING STARTED
Go out and shoot a typical scene with high contrast / exposure problem areas. (Foreground objects with a harsh background sky, interior settings looking into direct window light, etc) This test run does not need to be the greatest composition. It’s an excellent way to walk through the entire HDR process without getting hung-up on trying to create an instant masterpiece. Get a good handle on the basic steps, and you can begin to refi ne the process from there. (It’s best to take a full lap around the track before trying to improve on style or lap-time). This will also give you a feel for the limits of the process, enabling you to shoot scenes with the highest technical eff ectiveness when attacking more creative compositions. Do not be afraid to shoot a LOT of bad HDR photos before getting to the good ones!
HDR WALK THROUGH
1. Shoot a shutter-speed bracketed photo sequence. (Use of a tripod is always recommended) Bracket as many frames as are needed to accommodate the exposure range of the scene. (Example 3 frame: “-1, 0, +1”)
2. Export camera images to TIF format (although direct conversion from RAW is possible, observed results have consistently produced superior images using TIF fi les to generate the intermediary HDR fi le. (Testing fi le formats with your specifi c software package is advised)
3. Import TIF images into your HDR software package. This will generate an intermediary 32-bit HDR fi le that is ready for “Tonemapping” into an 8-bit output image. (Note: Save the 32-bit HDR fi le to disk and work from that if you intend to output multiple Tonemaps of the same image with diff erent settings. Test features like alignment and noise reduction with your software package. They can take signifi cantly more processing time and often reduce detail depending on the specifi c images. Observed results have produced superior results using post-processing NR)
4. Make Adjustments to slider settings and/or use presets within HDR software
5. Export resulting HDR Tonemap image to an 8-bit or 16-bit TIF image*
*Repeat steps #4 and #5 as desired with diff erent settings for further compositing in standard photo-editing software
6. Edit Tonemap(s) in standard photo-editing software to further fi nish the image. Treat the Tonemap(s) as though they were source images from your camera and run a full postprocess. (Layer Blending, Tone/Curve Adjustments, Colour Correction, Sharpening, Noise Reduction**)
**A word on noise reduction: There may be instances where selective NR is required. Typically high detail areas yield low noise, while softly gradient and low light shadow areas tend to produce high noise. This noise can be reduced without eliminating detail areas by layer stacking an NR fi ltered image over an unfi ltered image using a layer-mask for easy selection editing.
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