In a Raster scan display, the image which has to be displayed is saved in a binary format (0s and 1s) in the refresh buffer memory. Then, a video controller is used to scan each and every line of the Refresh Buffer Memory. The lines are scanned from left to right and when a line is finished again the controller moves to the next line and scans the line from left to right and so on. Then, a frame buffer memory which holds the coordinates of all the screen points is used to determine the coordinates of the screen. After that the actual image is produced in the Cathode Ray Tube.