Canon PowerShot A720 IS User Manual page 36

Various Shooting Methods 1101
l_l Adjusting the Exposure Compensation []
[] See Functions Available in Each Shooting Mode (p. 206).
Adjust the exposure compensation to a positive value to avoid making the
subject too dark when it is backlit or shot against a bright background.
Adjust the exposure compensation to a negative value to avoid making the
subject too bright in night shots or when shot against a dark background.
To Cancel the Exposure Compensation
Follow step 3 to restore the compensation value to [0].