Styles and Techniques

High Dynamic Range (HDR)

Chances are, if you take a peek at the camera on your smartphone, you’ll notice a setting marked “HDR.” If you happen to use it, you’ll be treated to an image of vibrant, high-saturation colors and strong contrasts that almost mimics a painting. The truth is, this isn’t an HDR image at all (although they are fun to look at.) HDR is an acronym for High Dynamic Range.  The method combines specialized multi-exposure shooting techniques with digital post-processing to produce contrast ratios that are generally un-achievable with a single exposure. It all sounds rather complicated doesn't it? The idea is actually fairly simple: If your camera can't get it all in one shot, shoot several and blend them together.

So what is dynamic range anyway? In real-world scenes, it's defined as the ratio between the lightest and darkest regions and can exceed 50,000:1. Unfortunately, digital camera sensors aren’t capable of capturing these ranges.  In fact, traditional media has historically been limited to around a 300:1 ratio...that's a big gap.  Ever shoot a picture inside your house on a sunny day? One of two things happens: (1) The interior is exposed and the exterior as seen through the window is blown out to white or; (2) the exterior is exposed perfectly but the interior is so dark you can barely make out any features. It’s not your fault. Cameras just aren’t capable of capturing such a broad range of light brightness…even with the groovy filter your iPhone applies.

To a large degree, this problem can be solved using High Dynamic Range shooting and processing techniques. With HDR photography, several exposures of the same image (1-4 underexposed images to catch the highlights that would otherwise be blown out, 1 properly exposed, and 1-4 overexposed to pick up the shadowed areas) are taken with a fixed camera (on a tripod) then digitally tone-mapped or blended together resulting in a much higher dynamic range. I find this method invaluable in a number of applications from architecture to (as seen below) scenes where the bright sun would make a single exposure nearly impossible.

The image above shows the seven exposures used to create the completed image below them. Note how by themselves, any of the seven exposures are either too dark or far too bright. When digitally tone-mapped together however, a much more compelling image can be created. Pier 60, Clearwater Beach, Florida.

The image above shows the seven exposures used to create the completed image below them. Note how by themselves, any of the seven exposures are either too dark or far too bright. When digitally tone-mapped together however, a much more compelling image can be created. Pier 60, Clearwater Beach, Florida.