Can I use a single photo?
Photomatix Essentials is intended for creating stunning images of high contrast scenes, and capturing a high contrast scene requires taking several exposures.
Photomatix Essentials merges the exposures and lets you adjust the result to your liking. You can either adjust the settings of the merge process itself with Exposure Fusion (using the 'Natural' preset), or adjust the settings of the merged image with Tone Mapping (e.g. 'Default', 'Balanced' or 'Painterly' presets).
However, it is still possible to enhance a single photo using the Tone Mapping settings intended for the merged image of an HDR scene. This means you can use Photomatix Essentials to load and enhance just one image, though this is not "HDR" properly speaking.
To enhance a single photo with Photomatix Essentials:
1. Drag & drop your photo (or click on the "Browse..." button to select it)
2. Check the box on the left of the thumbnail and click on "Next: Adjust & Preview"
Note: If you often use Photomatix Essentials with single photos, you can turn on an option in Preferences that will automatically check the box next to the image, saving you from having to do this before going to the next step.