Real-time synchronisation of front and back side printing in double-sided web printing

A system and a method for synchronizing printing of images on both sides of a web (20) in a double-sided web printer are described. The method includes (a) printing a first image (R) on a first side of the web (20) by a first printing device (1); (b) printing a second image (V) on a second side of the web (20), opposite the first side, by a second printing device (2); (c) sensing a position of theweb (20), relative to the second printing device (2), by a web position measuring means (65); (d) real-time communicating an electronic printing position signal, representative for the printing position of the first image (R) on the web (20), between the first printing device (1) and the second printing device (2); and (e) printing the second image (V) synchronized to the first image (R) based onthe electronic printing position signal and the position of the web (20) relative to the second printing device (2).