The Heaven and Hell of Architectural HDR
by Dennis Jones
September 01, 2010 — After years of hauling around a beast of a 4 x 5 camera and the requisite complement of lighting equipment, photographing architectural interiors digitally is a comparative pleasure. You might think that adding HDR to the mix would simplify things further: Set up the camera, bang away a bunch of brackets, process in Photomatix and voilà—perfectly balanced lighting. Well, yes and no. Architectural photography and High Dynamic Range (HDR) photography is a match made in both heaven and hell.
Balancing the extreme contrast of interior and exterior light in homes designed around a spectacular mountain view has always been a goal, especially when photographing the high-end residential architecture my clients build and design. The advantages of combining brackets and shooting interiors during the day seemed like a dream.
In olden times, properly capturing the view along with the interior on film, without it looking obvious, required thousands of watts of strobes and a mastery of the difficult subtleties of architectural strobe lighting. My dilemma has always swirled around the tens of thousands of dollars worth of tungsten or halogen lighting already designed into the home. This being an integral part of the design, once again, how do you balance it with an exterior view?
The advent of digital has easily solved the problem with multiple exposures and different white balances. Sure, it had been possible to do the same with film and filters on a 4 x 5, but registration was always an issue. I generally solved the problem by shooting at dusk or before dawn, augmenting the designer lighting and waiting for that short window when everything balances. This, of course, provided that beautiful blue exterior light, the result of cool daylight on tungsten film. This lovely dusk light is still a look desired by architects and builders, but as always, it requires working late and getting up very early.
Enter the dream of Architectural HDR. “Wow!” I thought in my naiveté. “No more working late and waking up at 4:30 a.m. to chase the dawn window light. I can do everything during the day and get a normal night’s sleep.” Wrong.
Learning From My Explorations in Architectural HDR
With all HDR photography, generating a set of bracketed exposures comes first. Thankfully, most high-end professional cameras have the capability of doing this automatically. First, I determine a proper exposure, set a custom white balance using a gray card, put the gray card in the scene and make a base exposure. I then set my Nikon D700 to record up to seven one-stop brackets around the base exposure. I haven’t found any distinct advantage to using more brackets or a bunch of narrower ½-stop brackets. A tripod is imperative, and I wouldn’t think of working without mirror up and a cable release (though a self-timer is an option in a pinch). Oh, and one other thing, shoot RAW. Don’t even bother with JPEGs. Why throw away part of your image?
This technique works fine with smaller rooms, especially rooms lit by bright natural light; light-colored bedrooms, bathrooms, and kitchens; and any room with windows behind the camera where lighting design is relatively unimportant, yet the view is. HDR also comes in handy when photographing daylight exteriors with deeply shadowed areas like verandas, porches or overhangs.
Enclosed spaces, such as offices with lighting of one color temperature, can benefit from this treatment, especially if no supplemental lighting can be used. Imagine a busy hospital, active 24 hours a day, where ceiling fluorescents are predominant. HDR is a way to tame the flare and balance the lighting these hideous light sources create.
Adding Supplemental Lighting
The real challenges come with large interior spaces—specifically, incorporating a view and designer lighting. To say the least, HDR, in its current technological state, does not do well with mixed light sources. Here is where the dream falls apart and hell begins. For all intents and purposes, I’ve given up trying to make a decent image under mixed-light conditions. The processing problems are too difficult and not worth my time. Instead, I’ll use the tried and true techniques of shooting at dusk—make one exposure balanced with the dusk window light and possibly blend it with a second image properly exposed and white balanced for the exterior scene—which is much easier and less time consuming.
Where supplemental lighting can come into play is by adding strobes, usually only one or two bounced off a white ceiling or through an umbrella or light box, into a room or part of a room with no windows, illuminating it from camera position. I’ll set the light to a stop or 1½ stops below my base exposure, enough to fill the shadows, but not enough so the strobes look obvious. Subtlety is one key to excellent architectural photography.
Unfortunately, and all too frequently, placing the lights without them reflecting in large windows proves elusive. Additionally, this technique does little to sculpt elements in the scene with light—another subtlety important to architectural photography. An interesting experiment, one with strobes to be controlled wirelessly, would be to vary their output along with each bracket. But I’ll leave that to someone else.
Where lighting really does play a nice part is with dusk or dawn exteriors. This is nothing new in architectural photography. Adding HDR to the mix gives things a new dimension.
After downloading the images into Lightroom (LR), I’ll generally do some lightweight processing. Using the Color Balance tool, I’ll take a reading off the gray card in the first base exposure and double check the white balance, syncing all the brackets if necessary. Tweaking the black clipping in the darkest brackets and recovering the highlights somewhat in the brightest can be advantageous. I bump up the Clarity, enhancing the midtone contrast of each bracket to compensate for its loss while tone mapping. I’ll also use the standard sharpening for my camera or utilize PixelGenius’ PhotoKit Sharpener for capture sharpening.
Definitely make certain you’ve adjusted your cataloging software for the chromatic aberration of your camera and its noise. As I employ Photomatix for all my HDR needs, I’ve found it perversely enjoys boosting aberrations and enhancing noise. Even though you wouldn’t think you’d need to, always check “Align images” and “By matching features.”
When importing the brackets into Photomatix, I frequently won’t use one or both of the extreme brackets, depending upon the scene. Sometimes, depending upon the strength of the exterior light, I’ll discard the two brightest brackets because light blooming around the windows can be a problem. The export settings are shown in the screen capture (above). I always check “Reduce chromatic aberrations” and “Reduce noise” even though I’ve dealt with this during processing in LR, and again, checking these, while not addressing them during processing, is asking for trouble. I always save the image as a 16- bit TIFF. Why work with anything less? I like to keep the automatic naming scheme so I know exactly which exposures I used. Be forewarned though, if you re-import the same brackets without changing the name—say, to try a different approach—it’ll overwrite your original HDR file.
Once I’ve imported the images, I work in the Details Enhancer. There are basically two approaches you can use: photorealistic and illustrative. For a photorealistic approach, use Maximum or High Smoothing. Adjust the Strength as low as possible. Keep the Color Saturation low, (Photomatix loves to add saturation in weird ways), Luminosity as high as possible and Microcontrast neutral.
Under the Tone Setting panel, adjust your White Point while watching the histogram. Keep the highlights below the clipped threshold. Again, Photomatix loves to clip highlights, and you’ll never get them back once clipped. Adjust the Black Point for maximum blacks without clipping, and adjust the Gamma slider for best exposure. I don’t mess with the color settings. Keep everything neutral or you’ll be sorry. In the Miscellaneous Settings panel, adjust the Highlight Smoothness to typically around 20, the less Light Smoothing and more Strength you use, the more highlight smoothing you’ll need to control halos and grayed-out highlights. Shadow Smoothness controls contrast and detail in the shadows. Use it in conjunction with Gamma. Zoom in to 100% to set the Microsmoothing. You can apply some Shadows Clipping, but watch your histogram, it will extend the shadow toe but the higher the shadows spike, the more pixels get muddied.
For an illustrative look, set the Smoothing on Mid to Low, adjust to a high Strength and set the Saturation, Luminosity and Microcontrast as above. Work with your Tone Settings and then control the Smoothness to reduce halos and noise, which will be more pronounced with low Smoothing and high Strength. But be aware of who your client is. If you’re trying to be artsy for your fellow photographers or the art market, fine, distort the image all you want. Builders, designers, architects and magazines, though, are not interested in illustrations. They want photographs.
Once you have as good an image in Photomatix as you can get (it won’t be close to perfect), re-import or save it. Keep in mind that what you see is not what you get! This is part of the “hell” of architectural HDR. An accurate preview is only found in the Tone Compressor, not in the Details Enhancer. Your saved image will be flat, saturated differently and can even have different colors, hence the importance of white balancing at the beginning and not messing with the Color Settings or adding saturation.
Here is where the fun begins; where you try to correct the problems introduced by Photomatix. First, I add back contrast with the Contrast and Clarity sliders in Lightroom or Bridge or by using a contrast curve with a Curves Adjustment Layer in Photoshop. Next, I use Nik’s indispensable Viveza plug-in to tweak selected areas; opening shadows, lowering highlights, saturating or desaturating colors and even subtly changing colors.
Sometimes this is all the image requires. But frequently, I’ll need to take the HDR file into Photoshop, open the base exposure, drag it onto a layer above the HDR image, add a layer mask, Layer > Layer Mask > Hide All, and paint with white to add elements from the original base exposure to the HDR image. I do this when I can’t correct something in the HDR file.
Why is Architectural HDR Hell?
I’ve alluded above to several things that make HDR difficult to use for architectural photography. The bottom line is that if you are working for a design professional they want reality and they want color fidelity. They don’t want “artistic” interpretations of their creations. HDR techniques, and Photomatix in particular, change colors and change contrast relationships. It is very easy to get enamored with excessive contrast and highly saturated color while working on an image. I know, I’ve done it, and then had to rework the images to keep my clients happy.
Dennis Jones has been a professional photographer for 25 years. With his company, Dreamcatcher Imaging, he photographs residential architectural and corporate event photography for his clients, many of whom are Fortune 500 companies. Dennis makes his home in Vail, CO, and blogs regularly about his travels at www.dreamcatcherimaging.com/blog.
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