Method for individually characterizing each copy on a printed sheet comprises applying a printing ink or coating on the sheet using a printing device connected to a laser device with a thermosensitive ink

摘要

Method for individually characterizing each copy (2) on a printed sheet (1) comprises applying a printing ink or coating on the sheet using a printing device connected to a laser device with a thermosensitive ink. Independent claims are also included for the following: (1) Device for carrying out the above method; and (2) Method for operating an image inspection system for quality assurance of an offset printing machine. Preferred Features: The ink is applied using an inkjet printing machine or a spraying device. The ink is transparent when not illuminated.