I found this on another forum…
GAIN – handles the overall brightess – but especially at the “top end”, that is, near the whites
OFFSET – handles the “low end” near the blacks
GAMMA – shifts the overall center of your image (brightnesswise) without moving either the “top end whites” or the “low end blacks”.
So if your picture is too dark – raise the gain (then adjust the offset a little lower to get decent blacks back)
If your picture is too light, try lowering the gain, and then raise the offset to regain detail in the blacks.
OR – simply “play around” with the gamma to lighten or darken your shot
Windows 7 64-bit, ASUS P6X58D, i7 960 3.20GHz, 24.0GB DDR3, 12TB connected storage
http://www.narrowroadmedia.com