EXHIBITION ORIGINALS AND OTHER FAKES [Inside the book, p. 24] DIFFERENTIAL IMAGES Projection, 2009 A differential image is a visualization of differences produced by the digital comparison of two images. In collaboration with the Fraunhofer Institute for Secure Information Technology (SIT) in Darmstadt, high-quality reproductions of original artworks loaned in conjunction with the exhibition were prepared with the actually invisible digital watermarking system 'ImageMark'. The 'original' reproductions were then compared to the marked ones in a differential procedure and the differences between the pictures were visualized.