A method for operating an electronic device (101, 601, 801, 1001, 1201, 1401, 2601), the method comprising: initialising (510, 730, 950, 1140, 1330, 1630, 1730, 2110, 2310) a camera system (180, 1802) of the electronic device (101, 601, 801, 1001, 1201, 1401, 2601), if a pre-set first condition is satisfied; controlling (520, 740, 960, 1150, 1340, 1640, 1740) the camera system (180, 1802) to operate in a sleep mode upon completion of the initialisation (510, 730, 950, 1140, 1330, 1630, 1730, 2110, 2310), wherein, in the sleep mode, the camera system is in a state incapable of capturing an image; in response to an input needing execution of the camera application through an input/output interface, controlling the camera system (180, 1802) to switch to a normal mode from the sleep mode, wherein, in the normal mode, the camera system is in a state capable of capturing an image; and displaying an image output from the camera system (180, 1802) in the normal mode on a display (160, 606, 806, 1006, 1206, 1406, 2660) of the electronic device (101, 601, 801, 1001, 1201, 1401, 2601) wherein the pre-set first condition comprises at least one of: switching of the electronic device from the sleep mode to the normal mode; execution of an application including a graphic element needing an operation of the camera system; displaying of a screen including the graphic element needing the operation of the camera system; detecting a pre-set context associated with the electronic device; and detecting at least one pre-set word from voice or text received by the electronic device. initialising (510, 730, 950, 1140, 1330, 1630, 1730, 2110, 2310) a camera system (180, 1802) of the electronic device (101, 601, 801, 1001, 1201, 1401, 2601), if a pre-set first condition is satisfied; controlling (520, 740, 960, 1150, 1340, 1640, 1740) the camera system (180, 1802) to operate in a sleep mode upon completion of the initialisation (510, 730, 950, 1140, 1330, 1630, 1730, 2110, 2310), wherein, in the sleep mode, the camera system is in a state incapable of capturing an image; in response to an input needing execution of the camera application through an input/output interface, controlling the camera system (180, 1802) to switch to a normal mode from the sleep mode, wherein, in the normal mode, the camera system is in a state capable of capturing an image; and displaying an image output from the camera system (180, 1802) in the normal mode on a display (160, 606, 806, 1006, 1206, 1406, 2660) of the electronic device (101, 601, 801, 1001, 1201, 1401, 2601) wherein the pre-set first condition comprises at least one of: switching of the electronic device from the sleep mode to the normal mode; execution of an application including a graphic element needing an operation of the camera system; displaying of a screen including the graphic element needing the operation of the camera system; detecting a pre-set context associated with the electronic device; and detecting at least one pre-set word from voice or text received by the electronic device. switching of the electronic device from the sleep mode to the normal mode; execution of an application including a graphic element needing an operation of the camera system; displaying of a screen including the graphic element needing the operation of the camera system; detecting a pre-set context associated with the electronic device; and detecting at least one pre-set word from voice or text received by the electronic device.