Exposure Fusion

If HDR seems too surreal for you, or you simply can’t get the look you’re after, try exposure fusion. This assigns weights to the pixels of each image in the sequence according to luminosity, saturation and contrast, and then, depending on these weights, includes or excludes them from the final image. So it takes the best bits from each image, combining them seamlessly to create a ‘fused’ image.

Exposure fusion is handy when shooting urban scenes, where often all you see is a ‘V’ of sky, with buildings rising on either side of the frame to the top corners of the image. Use an ND grad to tone down the sky and you also end up darkening the tops of the buildings. It may be possible to select the darkened parts of the building in post-production and lighten them, but this rarely looks convincing so it’s better to shoot a sequence of exposures and combine them.

The end result is far more subtle than HDR, although exactly the same software is used. In this case I used Photomatix Pro 4.0.2 again, and the same set of raw files as for HDR so you can make a direct comparison between HDR and exposure fusion.

Creating the final composite image follows the same process of dragging and dropping the raw files into Photomatix Pro. However, when the preview image and presets appear, click on Exposure Fusion at the top of the toolbox window instead of Tone Mapping so a different set of sliders appear, then choose one of the Fusion presets from the options below the preview image. In this case I found that fusionadjusted gave the best effect. Then, after a few tweaks with the sliders, it was job done.

CREATING YOUR SEQUENCE OF EXPOSURES

Ideally, you should mount your camera on a tripod when shooting exposure sequences for HDR and fusion so it doesn’t move between frames, otherwise the images may not line up correctly when you combine them. The exposure increments you use depend on how contrasty the scene is. I tend to shoot -2, -1, metered, +1 and +2 stops, although if the scene is very contrasty, as it was for the street scene used here, I may bracket from -3 to +3 stops in full-stop increments so I end up with a sequence of seven images.

I normally shoot in aperture priority exposure mode and adjust the exposure between frames using the camera’s exposure compensation facility. However, it is quicker to use your autoexposure bracketing, or to create a custom function specifically for shooting exposure sequences.

Tutorial 3:55 PM