The present invention provides a method for obtaining a composite image, which performs a mathematically correct image-processing on images obtained by wide-angle lenses which are rotationally symmetrical with regard to an optical axis, to achieve a desirable projection system. The present invention also provides a variety of imaging systems using the method. Further, the present invention provides a CMOS image sensor which has an accurate arrangement of pixels to perform image-processing using hardware without the need for image-processing by software.