读入三幅图像，手动在三幅图像中选取控制点（图1和图2间3对，图2和图3间3对），实现图像拼接并显示(Readin three images, manually select control points in three images (3 pairs of figures 1 and 2, 3 pairs of figures 2 and 3), to achieve image mosaic and display)