How to compare original image to edited image
How can I compare my original image to my edited image while still inside of the HDR Efex Pro 2 interface?
The Compare button at the top of the HDR Efex Pro 2 interface has the option to compare your edits to either the Default Tone Mapping setting within HDR Efex Pro 2, or to the Middle Exposure of the original bracketed image series. If you are editing a single image, the Middle Exposure setting will show you the original image.
To change the option of what your edits are compared to, click History on the left side of the interface, and set the yellow selector tool to either Default Tone Mapping or Middle Exposure.