High Dynamic Range (HDR) Photography has quickly grown into a popular form of photographic expression. It is both loved and loathed depending upon who you discuss the subject with.
Many photography purists oppose the technique and declare it to be unnatural or over-processed. Other photographers embrace it for its many benefits and opportunities.
The perspective that matters the most of course is the audiences… they love HDR. The goal of this article is to help you understand the technical approach behind the photography and understand the limits of all digital cameras.
HDR: Strictly Defined
HDR is a shorter way of saying high dynamic range imaging. The key here is the dynamic range of the resulting image
(which is just a fancy way of saying the difference between the brightest white and the darkest black in a scene). HDR is a way to use multiple exposures to capture a scene when the lights range is wider than the cameras ability to capture the data.
A common measurement in photography is a stop of light. Each time you add a stop of light it means you double the amount of light. If you exceed a cameras ability to capture light, those areas will become clipped (showing only white or black and no details). For most digital cameras, the built-in dynamic range is between four and five stops. Our eyes can capture between 11 and 14 stops of light, depending on which expert you believe.
One of the reasons that HDR photos look so good is that they can show details that are traditionally lost in a typical photograph. This increased contrast can be compelling to the audience and really keeps their attention. But how is this range achieved? It all comes down to tricking the camera and doing some extra work.
HDR: A Three Step Process
The biggest mistake HDR shooters make is trying to rush the process. Some think its as simple as shooting the photos and running them through a merging application. Others try to save even more time and use in-camera HDR solutions. While both of these options can make a better photo than just a traditional exposure, they don’t really embrace the full capabilities of HDR imaging. For that, you need to truly take a three-step process.
Using the bracketing option on your camera (or manually adjusting exposure), you’ll successfully capture two or more shots. The most common number of exposures taken is three, in which a base exposure is used and then an under- and overexposed image are acquired to preserve the highlights and shadows. Typically these multiple exposures are taken from a tripod to ensure that there is no movement between each exposure. However some users do shoot handheld and rely upon the software to help them align the images.
You can use any combination of exposures to properly show the scene. The wider the dynamic range of the scene, the higher the number of exposures you’ll need. If the light source is directly in the frame, you may need as many as seven exposures. Alternately, some photographers choose to just increase the amount of exposure compensation between the shots.
Don’t forget that all the old photographic rules apply. You need to use good judgment. Theres no substitute for great light, a great subject, great composition, picking the right angle and lens, etc. Simply applying HDR techniques to a bad photo just makes it into a bad HDR photo (that you spent more time on).
The next task you’ll perform is merging. This process can be handled using tools built right into Photoshop or using dedicated stand-alone applications. There are also a wealth of third-party tools to choose from (which well explore a little later). Many of the software tools can compensate for ghosting (caused by slight camera or subject movements) as well as resolve alignment issues.
There are two major approaches to creating a HDR image:
- Merge-only. If you shot JPEG or TIFF, you may choose to bypass preprocessing your photos. Some photographers also bypass developing their raw files and just pass the default values from their camera to their processing app. This is less desirable than taking the time to tweak the photo.
- Develop and Merge. By processing the individual panels (especially if they are raw photos), you can improve the end results. This approach takes extra work but can produce dramatically better results. Don’t develop all the files manually. Just use the base exposure (the one with 0 EV) and then sync its settings to the other exposures.
Once the source images are merged, you’ll be able to adjust the new image to refine its appearance. There are several ways to approach this task and they all depend upon your personal goals. The same source photos can be used to create a photorealistic image with improved dynamic range, a surrealistic painting, or a dramatic black and white photo.
In most HDR software, you’ll find useful presets that can get you close. Its then possible to refine the image using a few tweaks of available presets. Some programs use simple sliders that you can adjust to get the result you want. Properties like Glow, Detail, and Saturation are some of the most frequently adjusted. But the fun doesn’t have to stop there.
You can continue to work on the photo using your photo editing software. Basic transformations like cropping and straightening can be undertaken to improve composition. Additional tonal and color correction can also be performed for corrective or even stylistic outcomes.
If you’d like to take a fresh look at HDR photography, we’ve got several guest experts who’ll be stopping by for the rest of the year. Our goal is to help you unlock more from your camera and make better looking photos. HDR is another tool you can use, and you’ll find it in many of the software applications you already use. Whether its Adobe Photoshop or Lightroom (which take very different approaches) or a dedicated tool like Photomatix from HDRSoft, HDR Photography has entered the mainstream of photo processing.
Be sure to join us for our first HDR Hangout… save the date for August 26, 2015.