Anatomy of an HDR Image

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I've been interested in High Dynamic Range (HDR) Photography for a while now, but have been too busy to start experimenting with it. Until last Sunday that is.

At a very basic level creating an HDR image is quite simple. It involves taking multiple, bracketed exposures of the same scene, then combining the images into a single image optimized to show the dynamic range of all of the exposures. This allows you "see" detail in the image that a single exposure just couldn't display. Sounds simple enough, but there are a few things you need to know before you start.

1. The Process:

To create an HDR image their are a few things you need to prepare.

  1. Tripod: For the best results when combining multiple exposures you'll need to ensure the image framing stays stable. This means you'll need to have your camera on a tripod. Don't try hand-holding your camera as you may be disappointed with the results.

  2. Cable Release: For the best results use a remote cable release to make your exposures. This helps prevent camera movement while taking each shot. If you don't have one, you might try your camera's timer.

  3. Bracketing: Read your camera's manual to see exactly how to set up bracketing, and to learn how many bracketed exposures you can take at one time. In my case, I'm shooting with the Nikon D3 that can bracket up to 9 exposures at once. Here, I bracketed 9 exposures with 1-stop increments. This was my starting point for this image and a good number of images for an acceptable outcome. But the rule of thumb is - more exposures are better than fewer exposures.

  4. Exposure: Put your camera in Manual Mode and expose for the highlights!!!! This is very important. Use the lowest ISO you can to minimize noise. I used ISO 200. Next, I wanted to maximize Depth Of Field (DOF) so I selected an f-stop of f/22. Then, I used my spot meter to find the brightest highlight in the image and set my shutter speed so that all highlights in the scene contain detail. In this case it was 1/50 second. This resulted in Exposure #1 in the bracketed sequence below.

    1. Point of focus:  Don't forget the 1/3-2/3 rule for focus and depth of field. That is, when you pick a focus point, the area that's in focus will be 1/3 in front of the focus point and 2/3 behind. The width (or depth) of this area is determined by the f-stop you choose. A smaller aperture setting (or higher f-stop) will increase the area that's in focus. That, combined with a wide lens (17mm in my case) maximizes potential DOF.

2. Ready-Aim-Fire:

Camera's on the tripod, cable release is attached. I've exposed for the highlights, and the bracketing sequence is locked in. All that's left is to fire off 9 frames. Here are the results.

Frame #1 is exposed as in Step 4 above. Frames 2-5 are underexposed by 4, 3, 2, 1-stops respectively, and frames 6-9 are over exposed by 1, 2, 3, and 4-stops respectively. These nine images will be combined into one HDR image. How the heck do you do that?

3. Create Your HDR Image

We're in the home stretch. Now it's time to combine your bracketed exposures into a HDR masterpiece. The problem is, you need an application to do it. Fear not, there are a few options out there. Let's take a look at two.

Adobe Photoshop® CS5 √√

File/Automate/Merge to HDR Pro... is the menu path in Photoshop® to access its built-in HDR creating application.

The process in Photoshop® is pretty straight forward, but seems to lack the robustness of other solutions. It will definitely merge your bracketed images for you, and allow you to make adjustments to the HDR image, but it may be some time before it's as good as its competitors.

Be sure to set aside time to play with the settings to understand exactly how they can change the look of your image. There are no visual "sample looks" or presets to help guide you. It's all trial and error.

NIK Software - HDR Efex Pro™ √√√√√

Earlier this month NIK Software announced their latest plug-in, HDR Efex Pro™. It works in Photoshop and Lightroom and has a processing engine that makes the Photoshop HDR offering seem more like a toy rather than a professional tool. The interface is easy to navigate and understand. And, if you're familiar with NIKs other plug-ins, you'll feel at home in this one.

It uses NIKs U Point® technology that allows for very targeted, precise adjustments to specific parts of your image. And unlike the Photoshop "Merge to HDR Pro" tool, this one has visual presets to get you started. You can customize and save NIKs presets to develop a unique look to your images that you can reuse. NIK has additional presets that you can download from their web site.

After installation, File/Automate/Merge to HDR Efex Pro... is the menu path in Photoshop® to access NIK Software's HDR plug-in. Export/NIK Software/HDR Efex Pro is the path in Adobe Photoshop® Lightroom.

This plug-in gave me great results right from the start. I selected my 9 bracketed DNG images in Lightroom®, exported them with HDR Efex Pro™, and it did the heavy-lifting for me. Then, I could take advantage of the presets to immediately give me a great look. I can tweak the NIK presets and save them as new presets to reuse on another image. The Photoshop Merge to HDR Pro does not offer these tools.

4. Conclusion

NIK's HDR Efex Pro™ beats the Photoshop Merge to HDR Pro feature hands-down. In my example it did a better job of creating the initial HDR image than its Photoshop counterpart. And for what it does, the $159.95 list price of HDR Efex Pro™ seems very reasonable. That, along with the presets and the ability to make changes and save them as new presets puts HDR Efex Pro™ in a different class altogether.

A Helpful Tool

Promote ControlIf you plan on shooting a lot of HDR images there's one other thing you might want to consider, especially if you camera's bracketing ability is limited. Promote Control, by Promote Systems, is (among other things) a hand-held bracketing controller for your digital SLR. It works with just about all professional DSLRs and attaches by cable to your camera. It puts you in complete control of the number and type of bracketed exposures you can make.

I saw a demonstration of this device that was amazing. The photographer made over 20 bracketed exposures even though his camera supported less than 10! It will even allow you to lock up your camera's mirror between exposures. And it even fires the camera for you once you input your settings.

The unit carries a list price of $329, but a quick internet search will result in lower prices from reputable dealers. You'll want to pick up a cable release for $18.95 too.

Be sure your camera is supported. You can find out by visiting Promote Systems web site.