an image reception system is disclosed , which includes a tuner for selecting one of broadcast channels of catv , a video detector connected to the tuner for deriving output signals having video signals and command data of the selected channel , a data fetch circuit for extracting the command data and character data out of the output signals derived from the video detector , a display controller for controling video outputs to be displayed on a display screen , and a key pad for supplying the control command to the display controller . in this case , the display controller includes a character generator for generating character signals to be displayed on the display and masking circuit for superimposing masking signals on the video signal on request .