HDR

While most photographic techniques were originally developed using film cameras, High Dynamic Range (HDR) photography is a relatively new technique that is only possible with digital cameras and powerful software. While many people think of HDR as a way to create dramatic and artistic pictures, HDR is primarily a practical way to overcome the limitations of modern digital cameras. https://www.youtube.com/watch?v=x7IE6cnkJ_c HDR overcomes several photographic challenges:

  • Blown-out skies. Normally, you can only get outdoor pictures with nicely exposed skies during the golden hours. HDR gives you perfectly exposed skies in any conditions. You can even turn a boring, overcast sky into dramatic storm clouds.
  • High contrast. Your eyes (and brain) are great at adjusting to contrasty lighting. If you look out a window on a sunny day, you can easily see both your indoor surroundings and the outside world, even when the outside world is more than 100 times brighter. With a single photo, you could only see one or the other—if an indoor photo included a window, the window would be blown-out. With HDR, you can capture both in separate photos and process them into a single picture.
  • Noisy shadows. Even with a professional camera at ISO 100, shadow areas show a great deal of noise. HDR exposes shadow areas as highlights in your camera, and then adjusts them in post-processing to look like shadows again—but without the noise.

HDR also provides an artistic opportunity. HDR tone-mapping accentuates the contrast in a picture, allowing you to create striking and dramatic interpretations of the original scene. Tone-mapping is a feature of HDR software that adjusts the bright and dark areas of one or more pictures to either show a greater dynamic range in a single image or to accentuate the differences between shadows and highlights. https://www.youtube.com/watch?v=MfvwqcmM6FQ

HDR Overview

At a high level, the process of creating an HDR picture follows these steps:

  1. Set your camera to aperture priority.
  2. Take an autoexposed photo.
  3. Take an underexposed photo by increasing the shutter speed while keeping the aperture and ISO the same.
  4. Take an overexposed photo by decreasing the shutter speed while keeping the aperture and ISO the same.
  5. Copy the photos to your computer.
  6. Use HDR software to combine the autoexposed, underexposed, and overexposed photos into a single picture.

This figure shows a severely backlit steam engine scene that had too much contrast to photograph normally. I took these three photos at different exposures, and then used HDR software, Photomatix Pro, to blend them into two different HDR pictures: one providing a realistic representation of what I saw, and one providing a more artistic rendition (next).

Locomotive in HDR

Locomotive in HDR

This is an excerpt from Chapter 11 of Stunning Digital Photography.