In this paper a new approach to fragile watermarking technique is introduced. This problem is particularly interesting in the field of modem multimedia applications, when image and video authentication are required. The approach exploits the cellular automata suitability to work as pseudorandom pattern generators and extends the related algorithms under the framework of the cellular non-linear networks (CNNs). The result is a novel way to perform watermarking generation in real time, using the presently available CNN-universal chip prototypes. In this paper, both the CNN algorithms for fragile watermarking as well as on-chip experimental results are reported, confirming the suitability of CNNs to successfully act as real-time watermarking generators. The availability of CNN-based visual microprocessors allows to have powerful algorithms to watermark in real time images or videos for efficient smart camera applications. Copyright (C) 2004 John Wiley Sons, Ltd.