There is described an inspection system (50) for in-line inspection of sheet or web material on an intaglio printing press, wherein the inspection system comprises an optical quality control apparatus for carrying out inspection of a printed area on a printed side of the sheet or web material, the optical quality control apparatus including a camera system (55) with one or more camera units each comprising at least one line-scan camera (56) for scanning and acquiring an image of the printed area while the sheet or web material is being transported in the intaglio printing press past the camera system (55). A location of the at least one line-scan camera (56) in the intaglio printing press along a delivery path of the sheet or web material is such that cyclical vibrations that spread periodically throughout the intaglio printing press during operation of the intaglio printing press do not occur while the camera system (55) is scanning the printed area of the sheet or web material and acquiring a complete image of the printed area.