A zoom method of a small digital camera is provided that includes searching a center search line of a photographic screen according to a set photographic mode and searching upper and lower lines based on the center search line so as to extract a color average value and a deviation of a photographic object. A size of a photographic object may be calculated based on the average value and the deviation. A zoom ratio may be set according to a size of the photographic object. A portrait mode and a text mode may be implemented by software without influencing a size of a mobile communication terminal and so as to fast process the zoom function.