There is no denying that HDR photography (high dynamic range) is here to stay. Even now, a few years since it grabbed the attention of photographers, it is a divisive technique. Some people swear by it, some despise it. One of the main criticisms of HDR is the hyper-realistic—even surrealistic—effect often used to make mundane images look striking.
HDR does not have to be like this, though. It was developed as a technique to expand the dynamic range of early digital cameras, allowing photographers to get closer to the dynamic range of their own eyes. In this tutorial, we are going to have a look at how to use HDR and keep the image looking natural.
One of the reasons HDR often looks unrealistic is that people are over-zealous with the number of shots they use. To get a natural looking HDR shot, you can get away with three different exposures: 1) the correct metered exposure 2) one to maintain definition in the sky, and 3) one to keep detail in the shadows. To get the very best image, think about your shot and use a steady tripod with your camera locked into position. Meter the exposure carefully and learn to use the histogram.
For the correct metered exposure, you are looking to get your exposure in the middle of the histogram without any clipping. “Clipping” is when the histogram disappears off the edge of either end of the graph. If it is off the right end of the graph, you are overexposing (clipping) the highlights. If it is off the other end, your shadows are too black; there won’t be any detail in the darkest parts of the photo. Adjust your shutter and/or aperture to get the best possible exposure according to the histogram.
With the correctly exposed shot taken, you will now expose for the sky. You will need to underexpose the image, bunching the histogram to the left of the graph and off the edge of it. Check the preview to see how well this shot is holding the sky details, making sure there is plenty of definition in there.
For the last shot, you are going to overexpose your image, trying to get the histogram bunching to the right—but not too far. You are looking to try and get some shadow detail in all but the very darkest shadows without blowing out the sky regions too much.
With the shots taken, it’s time to put the HDR image together. There are a multitude of programs and plugins out there to do this, but the basic principles are the same. For this tutorial we will use a recent incarnation of Photoshop.
The easiest way to merge the images is to put the three selected images in a dedicated folder. With Photoshop open, go to the menu and select Automate – Merge to HDR. Browse for the three images and click OK.
Once Photoshop has done its calculations, it will open a new window where you will adjust the image. On the lower right of this new window you will see two tabs, Advanced and Curve. Click on the Curve option.
Click and drag the left hand side of the curve upwards to introduce some detail in the shadow areas. Do this carefully so as not to introduce excessive noise into the shadows. You can make two or more points at the right end of the graphs to raise the dark areas to a suitable level. Once you’re happy with the shadows, you are going to apply a similar technique to the right side of the graph (the highlights).
In this case, drag the curve downwards near the right end. This will have the effect of darkening the highlights, adding further definition to your sky and clouds. Again, you can make two or more points to get the best adjustment. Keep an eye on the final image. Remember, you are aiming for realistic, not hyper-realistic. Lastly, make some adjustments near the middle of the curve to make sure your midtones are at an acceptable level.
Lastly, if you notice any haloing in the image (bright fringes around areas of contrast), you can reduce the Edge Glow slider above the Curves. To finish the image, slide the detail slider to get the best combination of contrast and detail without going overboard.
Once you are happy, click OK and the image will be opened in Photoshop, where you can make any final required adjustments.