This book constitutes the thoroughly refereed post-conference proceedings of the Second International Conference on on Signal-Image Technology and Internet-Based Systems, SITIS 2006, held in Hammamet, Tunisia, in December, 2006.

The 33 full papers were carefully reviewed and selected from the best papers presented at the conference and are presented in revised and extended form. Part of the papers focus on the emerging modeling, representation and retrieval techniques that take into account the amount, type and diversity of information accessible in distributed computing environment. Other contributions are devoted to emerging and novel concepts, architectures and methodologies for creating an interconnected world in which information can be exchanged easily, tasks can be processed collaboratively, and communities of users with similarly interests can be formed while addressing security threats that are present more than ever before.