High-dynamic-range imaging HDR is a photographic technique that allows for a wider range of colors and a greater dynamic range to be captured in an image. HDR photos show a high level of detail and color saturation from the darkest to the lightest areas of the photo. Normal photographic techniques require the photographer to make a choice of exposure that is best suited to the primary objective of the shot. Say for example you were photographing a building on a bright cloudy day, since the subject is the building and not the clouds the photographer would choose an exposure that would render optimum exposure of mid to dark tones of the image where most of the visual information for the facade of the building lies but the sky which will be much bright will be blown out. HDR allows you capture both the sky and the building in rich color and detail.
HDR photography does not require specialized equipment beyond a tripod and camera capable of taking varied exposures. The technique basically boils down to taking a series of fixed aperture photos in a range of exposures. This technique is called bracketing and many cameras can do it automatically. It was traditionally used by photographers as a form of insurance to guarantee an image would look good when they were shooting film in an varied lighting situation.
HDR makes use of this technique to create a composite image with the best features of each of these images, so there is no part of the photograph without proper exposure.
You can create High Dynamic Range images with any rudimentary image editing tools but to do the really fine work I suggest you invest in Adobe Photoshop. It’s a great all around tool for all your image editing needs and has a number of tools that make creating HDR images a snap.
What follows is a quick tutorial for those of you interested in doing High Dynamic Range Photography. I will assume you have a nice (but not too nice Digital SLR) and Photoshop. For those of you who can’t justify the cost of Adobe Photoshop, I recommend you consider GIMP for general photo editing it’s free and can do manually just do just about as much as Photoshop without some of the streamlined options for production work and raw camera integration and Luminance for HDR processing. See Links at the bottom of this article.
Base Photo
High Exposure
Low Exposure
When you shoot your images bracket your photos +/- 1 to 2 brackets and use a tripod. (Every camera is different so check your manual.) You can bracket in multiple steps and combine anywhere from two to ten images. Three is fine for most situations, capture your images in raw format whenever possible. There is significantly more information in a RAW image file and a jpg. Digital CMOS technology is improving rapidly but for now most digital cameras are weakest in the darker areas so make sure your maximum over exposure adequately captures detail in the darkest area of the image. Transfer the RAW image files to your computer. In Photoshop, scroll to bottom third of the File tool bar select Automate > Merge to HDR Pro… Select the bracketed images in RAW format. Photoshop has a number of HDR presets with numerous gaudy effects so don’t be afraid to try your own custom adjustments (you can copy the settings I used above for a start) and remember don’t go over board with the color saturation or your photos will end up looking like a Thomas Kinkade.
Final HDR Photo
Photoshop Excellent professional image editing tool. I recommend it to anyone who has a camera.
GIMP Great “Free” Photoshop alternative. Gimp is open source and can do much of what Photoshop does without some of the bells and whistles.
For those of you interested in a dedicated HDR software tool there are a number of Free and Professional options.
Luminance is “Free” and very good.
Photomatix is considered to be one of the best of the Professional HDR Tools and you can buy it for $99.
HDR as a technique is extremely flexible so don’t be afraid to experiment and have fun.
In the next lesson I will show you combine HDR images into a perspective corrected panorama.