1. An image composing method of a portable terminal, comprising the steps of: photographing an object to produce a photographed image when a key for photographing using a background image is input; extracting contours of the background image and the photographed image; and combining the background image and the photographed image such that the extracted contour of the background image is matched with the extended contour of the photographed image, wherein combining the background image and the photographed image comprises: calculating gradients of the contours of the photographed image and the background image at each pixel; calculating a sum of values obtained by multiplying the gradients of the pixels of the background image and the photographed image, while moving, enlarging and/or reducing the photographed image; determining a position and a magnification or the photographed image when the calculated sum is maximized; correcting the photographed image according to the determined position and magnification; and combining the background image and the corrected image.