A display system is provided which determines an effective image area by automatically detecting a boundary between the effective image area and a non-image area created owing to the difference between the pixel numbers of the camera image sensor and television signal, to thereby display the images on a monitor by adjusting a display size and position suitable for the effective image area, whereby an inappropriate display size and position are avoided from being set while a lighting device for illuminating a camera's field of vision is off. The display system receives a signal notifying about activation of the lighting device from the lighting controller that provides on/off control of the device; the system then determines the effective image area if the device is on, and does not if it is off.