1. An image processing apparatus comprising: a movement amount detection unit to obtain movement amounts; an image synthesis unit generating a synthesized image by inputting a plurality of images photographed at different positions and connecting strip areas cut from the images, in which the movement amount detection unit (i) performs a matching process involving pixels of the present image and those of the immediately preceding image to determine a number of pixels which have moved between the present image and the immediately preceding image and (ii) utilizes the determined number of pixels to obtain a respective movement amount, wherein the image synthesis unit is configured to determine the strip areas based on the movement amounts and allowable set positions which involve: (i) generating a left-eye synthesized image applied to display a 3-dimensional image by a process of connecting and synthesizing left-eye image strips set in the images and generating a right-eye synthesized image applied to display a 3-dimensional image by a process of connecting and synthesizing right-eye image strips set in the images, and (ii) performing a process of setting the left-eye image strip and the right-eye image strip in an allowable range of set positions of the left-eye image strip and the right-eye image strip used to generate the left-eye synthesized image and the right-eye synthesized image, which are at different observing points, applicable to display the 3-dimensional images by acquiring the allowable range from a memory or calculating the allowable range.