Some images defy one-time correction due to wide
variations in lighting or color temperature. Lighting issues are
common with wide scenes that include clouds, ocean surface, or a mixture
of natural light and flash. Over-under images are especially
troublesome. The best way to tackle these problems are to make at
least two copies of the original image, adjusting each copy to address
one problem, and blending them to create your perfected image.
DSLR users shooting RAW will reap the greatest benefit using this