HDR photography creates a very surreal effect, where every part of the image is “properly” exposed and well defined. I think of it as hyper-realism, because a properly done HDR image (when done properly) is one that best reflects what I see with my eyes.

Technically, this is done by combining multiple versions of the same image, all of which have been exposed slightly differently. It’s easy to push the images too far, however, and ruin the effect – but if you’re good, you can create simply stunning photographs.

Half of what we’re going to do is done in-camera and requires bracketing or the ability to shoot RAW files (or both). The other half is done on the computer, where you can use software to put the pictures together. For this tutorial we’ll use Photomatix from a company called HDRsoft, which is specifically designed for this type of thing… though you could also use Photoshop. As an aside, though I’ve outlined how I approach the process in a little more detail, you can also view the official HDRsoft tutorial here.

Step 1: Getting A Sequence Of Shots

The first step is acquiring the source material. Like I said above, you need multiple images, but there are a couple ways of getting them.

Bracketing

The easiest (and best) way of generating multiple shots of the same subject using different exposures is through the use of Exposure Bracketing on your camera. Three shots is often enough, but if your camera supports a greater number of frames in the bracket, you can try using more than three.

When you set up bracketing on a Digital SLR, you can usually set the number of frames in the bracket, but you can also set the exposure value difference between those frames. I’d suggest +/-2.0 stops, though you can get away with less or more depending on the contrast differentials in the scene.

Now you have to take three (or more, if you have your frames set higher for the bracket) pictures of your scene or subject. The trick here is that you have to shoot the pictures fast, and there can’t be any movement in the scene or in the camera. Any little movement will reflect in the end image when you overlay the set of images.

Single RAW File

There is another technique for doing an HDR image of a moving subject, and that involves a single RAW file. While we ideally want three (or more) images shot at different exposures, this doesn’t work if the subject is moving around – since they would move from frame to frame.

Instead, use a single RAW file (properly exposed) and load it into your favorite image editor. Save a TIFF copy of it at -2 EV, another at 0 EV change, and a third at +2 EV. Since we’ve stripped the EXIF data from file by saving it as a TIFF, Photomatix won’t know the difference and will properly process.

Step 2: Generating An HDR Image

Open the three images into Photomatix. From the HDRI menu select “Generate HDR”, and select “Use Opened Images” when it prompts you to use them. It will then attempt to determine the exposure variance between the shots, so just make sure it’s got it right (-2.0, 0, and +2.0). Click OK, and check “Use Standard Response Curve”.

If you are using a sequence of shots from the camera (as opposed to from a single RAW file source) you should check “Align source images” so Photomatix will try to line up any slight differences in composition. This is advised, even when you’ve shot using a tripod.

Now click Ok, and after a minute or so you’ll get an HDR image. At this point, it hasn’t been tone mapped to look good on your screen, so it won’t appear quite right. It will likely look overexposed, but you’re making progress. You’ve now got a 32-bit image that Photomatix will convert to a 16-bit or 8-bit image, but still retain all the tonal information we’ve compiled.

Step 3: Tone Mapping

Before you’ve begun the Tone Mapping process, you may want to save the source HDR image (in case anything goes wrong). This is a big file, though, so before you start saving all your HDR images for archival purposes, make sure you can afford the space. Then go to File > Save As, and save it.

Now go to the HDR menu and click on Tone Mapping.

At this point you’ll be looking at the Tone Mapping window using the “Details Enhancer” method, which allows you to see the HDR image as it maps lighter pixels onto dark ones and vice versa.

You can now experiment with the sliders to get the desired effect of balance. There aren’t any rules here – so this is typically the “make or break” portion of the process, where some people push the image too far. With an artistic eye and a little knowledge of what the sliders are controlling you can avoid that, and make a beautiful image instead.

Luminosity
This slider will effect the brightness. By moving this slider, you will boost the detail in the shadow areas and affect the overall luminosity of the image.

Strength
Essentially effects the contrast of the image, and moving this to the right will boost it. Set this too high and you’ll get halos or glowing edges.

Color Saturation
Increases the RGB values and results in a higher degree of color in the image.

Micro-smoothing:
Smoothes out local details enhancements, and reduces noise. By inducing micro smoothing, you can get a really surreal and arty look to your image.

Light Smoothing:
Set this too low (anything below 0), and you’ll get terrible results. Increase it a little to help remove the “halo” or “glowing” effect around objects.

Trey Ratcliff is one of my favorite “unknown” photographers. He’s only unknown because he doesn’t really do this for a living, not because he potentially couldn’t. Since he first visited Chernobyl and published Part 1 of his two part photo essay from the hot zone, Trey garnered the attention of the online community and his blog has earned itself a lot of traffic.

For a living, Ratcliff works for a game company… in fact, he’s the CEO. During his travels, he takes along his camera and shoots high dynamic range images of (seemingly) everything he sees or can get close to.

Despite the “fad” impression I get surrounding the hype of “HDR” images these days, it’s tough not to love their rich, hyper-real quality. What’s nice about Trey’s photography is his use of HDR. Very few people who attempt HDR imaging seem to understand when enough is enough, and push their images too far. Trey’s photography could easily be misunderstood for impeccably lit traditional photography, but they still have that slightly processed look which is typical of HDR.

Go visit the two part Chernobyl Adventure over at Trey’s blog, “Stuck In Customs“.

We’re not talking megapixels here, we’re talking gigapixels – with resulting images that are so highly detailed, you can zoom in to even the tiniest object in the distance and bring it in with clear and crisp fidelity.

xRez is like a studio, or a collective of photographers who are commissioned for special projects. They have some unique and highly specialized equipment designed for the purposes of gigapixel level panoramic work, high dynamic range photography, large scale “full dome” panoramas, etc. It’s the sort of stuff we all dream of doing, but very rarely get a chance to.

By combining powerful 3d tools and techniques appropriated from the visual effects field, possibilites arise of new imagery and animation that are truly novel and unprecedented. Applications of these new techniques can range from experiencing stunningly large prints in fine art gallery installations, providing a substitute to live-action shooting in feature film backgrounds, and enriching a national park visitors understanding and interpretation, to name a few.

The team currently consists of Greg Downing (who specializes in 3D based imaging), Eric Hanson (a visual effects designer), and Ron Shirley (a film and photography major) and together they have worked on visual effects for numerous outfits and companies. All these guys are teachers as well as professionals, and they’ve got some interesting work in their online portfolio that shows off this gigapixel obsession.