Can I use a single photo?

Photomatix Essentials is intended for high contrast scenes.

A high contrast scene requires taking several exposures to properly render details from both the darkest and brightest parts.

If the contrast of the scene is high, but not very high, you can still take just one exposure and use Photomatix to enhance it. You can even use Photomatix for a photo with low contrast, to add a 'Painterly' or 'Grunge' look to it, for instance.

To use Photomatix Essentials with a single photo, you just need to drag & drop the photo (or click on the "Browse..." button to select it). Then, click on the 'Next: Adjust & Preview' button.