1. A method of previewing an image on a terminal, the method comprising: starting, by the terminal, at least one camera of a rear dual camera of the terminal; controlling, by the terminal, the at least one camera to enter a low-power monitor state; obtaining, by the terminal, brightness information and color temperature information of the current scene using the at least one camera in the low-power monitor state; updating, by the terminal, in real time automatic exposure parameters of the current scene using the obtained brightness information, and updating in real time color temperature parameters of the current scene using the obtained color temperature information; obtaining, by the terminal, an image of the current scene using a camera upon reception of an instruction for starting the camera; correcting, by the terminal, color temperature and brightness of the obtained image using the color temperature parameters and the automatic exposure parameters of the current scene updated in real time; and outputting, by the terminal, the corrected image as a preview image.