A new watermarking method with obfuscated quasi-chirp transform

Kazuo Ohzeki, Yuanyu Wei, Yutaka Hirakawa, Kiyotsugu Sato

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)


Watermark detection software is obfuscated using a table to hide embedding and detection algorithms. As the table size is limited, the block size is also limited for watermarking. To address this situation, a new quasi-chirp transform is developed to improve embedding efficiency. The quasi-chirp transform is different from the conventional DCT or Fourier transform. It contains multiple frequency components in a single basis of the transform. It disperses image data rather than compressing it, as the DCT does. The dispersed data increases the range for embedding watermarks. The chirp transform is able to embed even on a flat area of an image. Using this chirp transform, embedding and detection experiments for image data with small block sizes were carried out. A high SNR and robust watermark with an evaluated obfuscation were obtained.

Original languageEnglish
Title of host publicationDigital-Forensics and Watermarking - 10th International Workshop, IWDW 2011, Revised Selected Papers
Number of pages15
Publication statusPublished - 2012
Event10th International Workshop on Digital-Forensics and Watermarking, IWDW 2011 - Atlantic City, NJ, United States
Duration: 2011 Oct 232011 Oct 26

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume7128 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference10th International Workshop on Digital-Forensics and Watermarking, IWDW 2011
Country/TerritoryUnited States
CityAtlantic City, NJ


  • detection
  • embedding
  • obfuscation
  • orthogonal transform
  • quantization

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science(all)


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