. . . "FIGS. 12A to 12E are views for explaining magnification correction, in which FIG. 12A is a view for explaining the magnification, FIG. 12B is a view showing the relationship between the position of a pixel actually written in a field memory and the original position of the pixel, FIG. 12C is a circuit diagram showing the circuit arrangement for magnification correction, FIG. 12D is a circuit diagr" .