When working with HDR software tools, there are many options. Its easy to get overwhelmed with sliders and presets. Theres a critical choice that needs to be made first. How do you want to merge the multiple exposures together? There are generally three options to choose from. Lets explore the benefits of each.
Fuse Exposures
The most subtle use of HDR is to simply merge exposures. If you want to capture a scene whos dynamic range exceeds the capabilities of a digital sensor, use this approach. In Photomatix, choose the method Fuse exposure with Fusion/Natural.
The benefits of this approach is that you can accurately capture scenes such as a backlit window or a sunset. The results are typically photorealistic. The images will typically show far less noise than a single exposure of the same scene.
The downsides of this approach are few. The image may end up lacking contrast and appear a bit flat. Thats easy to fix however with the use of a Curves or Levels adjustment afterwards. You may also need more memory when working with several images or high bit-depths.
Tone Mapping
For those of you who like the HDR look, it is typically achieved through tone mapping. Tone mapping essentially retains localized contrast and can be used to create a dynamic image. The look can be used subtly or to dramatic (or even surreal) effect. In Photomatix there are two tone mapping methods: Tone Mapping with Details Enhancer and Tone Mapping with Tone Compressor.
Tone mapping generally offers several presets and customizable options that can be used to refine an images appearance greatly. This method is also quite effective at preserving the details of shadows and highlights in the image. An advantage of working with tone mapping in Photomatix is that the HDR image can be saved in an editable format so multiple tone maps can be applied.
The tone mapping method does have a couple of drawbacks. Any noise will tend to increase in the image, so consider using the noise reduction option of the tool. The method also tends to introduce potential color cast issues into areas containing white or gray.
Which method should you use?
The choice is up to you. Of course you can also choose to try all three methods to see which one works for the images being processed. The lesson here to take away is that HDR can be as subtle or dramatic as you want it to be.
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