Keystone compensation for image storage systems
Joseph F. Stephany, Werner E. L. Haas · Applied Optics · 1976
Certain types of optical storage devices are preferentially read out with off-axis illumination. This method, however, produces keystohing of the projected image, which is a serious disadvantage. In this paper a double Keystone system is analyzed in which a controlled distortion is introduced by the input system to compensate for the distortion by the projection system. The necessary equations to solve the system are presented in terms of a single parameter which makes a simple solution practical.