1. A projection control method for a projector connected to an image capturing device, the method comprising: predetermining hand gestures, assigning an operation function of an input device to each of the predetermined hand gestures, the hand gestures comprising a first hand gesture associated with execution of an operation function of a scroll wheel of a mouse, a second hand gesture associated with execution of an operation function of a right mouse button of the mouse, and a third hand gesture associated with execution of an operation function of a left mouse button of the mouse; receiving an image of a speaker captured by the image capturing device when an electronic file is projected onto a screen by the projector; identifying whether a hand gesture of the speaker matches one of the predetermined hand gestures; searching a fingertip of one finger of the hand gesture, and projecting a cursor on an image of the fingertip, the cursor being controlled in the same position when a hand of the speaker leaves from the front of the screen, and the cursor being controlled in the same position when the hand of the speaker is moved; and upon the condition that the hand gesture matches one of the predetermined hand gestures, executing a corresponding assigned operation function.