1. A method performed by a device having a front camera, a rear camera and a touch display screen, comprising: acquiring images through the front camera in a self-portrait mode, the front camera disposed at the same side of the device as the touch display screen; displaying a live main preview image based on the images acquired in the self-portrait mode; and displaying a live mini preview image based on the images acquired in the self-portrait mode in a partial region of the touch display screen proximate to a lens of the front camera, wherein, in the self-portrait mode, the live mini preview image is displayed with the live main preview image.