Original scientific paper

Robustness of a DFT based image watermarking method against am halftoning

Ante Poljicak orcid.org/0000-0002-4339-448X ; Faculty of Graphic Arts, University of Zagreb, Getaldićeva 2, 10000 Zagreb, Croatia
Lidija Mandic ; Faculty of Graphic Arts, University of Zagreb, Getaldićeva 2, 10000 Zagreb, Croatia
Darko Agic ; Faculty of Graphic Arts, University of Zagreb, Getaldićeva 2, 10000 Zagreb, Croatia

Abstract

In this paper the robustness of a Discrete Fourier Transform (DFT) based image watermarking scheme to amplitude modulation (AM) halftoning is evaluated. Halftoning is used for reproduction of continuous images. Thus, it is important that a watermarking method is robust to halftoning. Three different shapes of clustered dots of AM (Amplitude Modulation) halftones are used (round, ellipse and line) with five different halftone frequencies (10, 13, 15, 40, and 60 line/cm). The tests where done on a dataset of 1000 images. As the metric of robustness, watermark detection rate, distribution of detection values, and ROC (Receiver Operation Characteristic) curves were used. The results showed that the watermarking scheme is robust to halftoning for halftone frequencies greater than 15 line/cm. Also, the type of AM halftone used has almost no effect on a detection rate.

Keywords

amplitude modulated halftoning; discrete Fourier transform; image; watermark

Hrčak ID:

69579

URI

https://hrcak.srce.hr/69579

Publication date:

27.6.2011.

Article data in other languages: croatian

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