(Matematički
fakultet, Beograd)
Abstract. Digital watermark is a pattern of bits inserted into an image, audio or video file, which contains information related to this file. The purpose of digital watermark is to provide copyright protection for intellectual property that is in digital format. Invisible digital watermark attracts greater attention than visible. It is not a simple task to make a good watermark. It must be imperceptible for the human observer; on the other hand, it must be robust against usual operations (change of brightness and contrast, cropping, rotation, lossy compression...) and against malicious attacks