Design and evaluation of sparse Quantization IndexModulation watermarking schemes

摘要

In the past decade the use of digital data has increased significantly. The advantages of digital data are,amongst others, easy editing, fast, cheap and cross-platform distribution and compact storage. The most crucialdisadvantages are the unauthorized copying and copyright issues, by which authors and license holders can sufferconsiderable financial losses. Many inexpensive methods are readily available for editing digital data and, unlikeanalog information, the reproduction in the digital case is simple and robust. Hence, there is great interestin developing technology that helps to protect the integrity of a digital work and the copyrights of its owners.Watermarking, which is the embedding of a signal (known as the watermark) into the original digital data, is onemethod that has been proposed for the protection of digital media elements such as audio, video and images. Inthis article, we examine watermarking schemes for still images, based on selective quantization of the coefficientsof a wavelet transformed image, i.e. sparse quantization-index modulation (QIM) watermarking. Differentgrouping schemes for the wavelet coefficients are evaluated and experimentally verified for robustness againstseveral attacks. Wavelet tree-based grouping schemes yield a slightly improved performance over block-basedgrouping schemes. Additionally, the impact of the deployment of error correction codes on the most promisingconfigurations is examined. The utilization of BCH-codes (Bose, Ray-Chaudhuri, Hocquenghem) results in animproved robustness as long as the capacity of the error codes is not exceeded (cliff-effect).