a television camera and display device , in which a transmission and reception utilizes quincuncial scanning with sub - sampling associated with an optical filter for reducing the diagonal resolution of the image . the filter prevents the folding of the spectrum when subsampling is employed , and permits the simplification of the device . the device may be implemented in both solid - state and vacuum tube form . it is applicable especially to high - definition television having only a restricted pass band and low sampling frequencies , and to the acquisition of and to the visual display of images in hdq mode .