|  |  | Step 2: Adjust the selection automatically |

Step 2: Adjust the selection
Click the Attach to Edges checkbox.
This will make Photomatix search for the nearest edges to your selection, and adjust the selection accordingly.
If the resulting selection is not what you wanted, you can try different settings for the Contrast and number of pixels.
A "High" value for the Contrast setting will find less edges, as it will not attach to lower contrast edges such as clouds for instance, while a "Low" value will find more edges.
The number of pixels sets the maximum distance in pixels from your selection where edges will be detected.
Once your selection is finalized, replace the selected region with a source photo as shown in step 3.