1. A system for merging images of an object, comprising a computer and a charged coupled device (CCD) for capturing images of the object, the computer comprising: a storage for storing images of different parts of the object and a location file which contains coordinate values of the images; an image merging unit comprising: a logic rectangle generating module configured for reading the images in the storage, obtaining heights and widths of the images, reading coordinate values of the images in the location file, converting the coordinate values to coordinate values measured in pixels, generating a pixel rectangle rcB for each of the images according to the obtained heights and widths, merging all the generated pixel rectangles rcB according to their coordinate values in pixels to form a logic rectangle rcA, and for calculating a reduction scale S of the logic rectangle rcA; and an overall image generating module configured for generating an image rcC by reducing the logic rectangle rcA according to the reduction scale S and a coordinate mapping; reading all the pixel rectangles rcB; reducing each of the pixel rectangles rcB according to the reduction scale S to generate an image rcD; and incorporating all the generated images rcD to the image rcC according to the coordinate mapping to form an overall image of the object.