Took place at the University of Split, Croatia, on the 14th - 16th September, 2004 and provided the same vibrant, cross-disciplinary, mixture of computer science and art that COSIGN has become famous for. The previous three COSIGN conference have been held at the CWI in the Netherlands ( COSIGN 2001. The University of Augsburg in Germany ( COSIGN 2002. And the University of Teesside in the UK ( COSIGN 2003. The proceedings for the 2001, 2002 and 2003 conferences are available online.