%0 Journal Article
%T A New QIM-Based Watermarking Method Robust to Gain Attack
%A Yevhen Zolotavkin
%A Martti Juhola
%J International Journal of Digital Multimedia Broadcasting
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/910808
%X We propose a new watermarking method based on quantization index modulation. A concept of initial data loss is introduced in order to increase capacity of the watermarking channel under high intensity additive white Gaussian noise. According to the concept some samples in predefined positions are ignored even though this produces errors in the initial stage of watermark embedding. The proposed method also exploits a new form of distribution of quantized samples where samples that interpret ¡°0¡± and ¡°1¡± have differently shaped probability density functions. Compared to well-known watermarking schemes, this provides an increase of capacity under noise attack and introduces a distinctive feature. Two criteria are proposed that express the feature numerically. The criteria are utilized by a procedure for estimation of a gain factor after possible gain attack. Several state-of-the-art quantization-based watermarking methods were used for comparison on a set of natural grayscale images. The superiority of the proposed method has been confirmed for different types of popular attacks. 1. Introduction Digital media have a great impact on many aspects of modern society. Some aspects assume that we deal with audio-visual data that relates to a person or an organization. Information about the relation quite often should be preserved. Watermarking approach is to insert the information in the media itself [1]. However, in that case the watermark might be intentional or not altered by the third party. In order to avoid an alteration the watermark needs to be robust [2]. Other characteristics except robustness may also be important. Watermark invisibility and payload are among them. Invisibility is important to assure that the quality of the media does not degrade significantly as a result of watermarking [3]. High data payload might be needed in some applications in order to define many aspects of ownership. In the field of digital image watermarking (DIW) digital images are used as a media (or host). DIW incorporates many different techniques and one of the most popular among them is quantization index modulation (QIM). Methods that belong to QIM are widely used in blind watermarking where neither original media nor watermark is known to the receiver [4]. For the purpose of evaluating robustness the watermarked image is being attacked and additive white Gaussian noise (AWGN) is the most popular condition for that. Theoretical limit of the channel capacity which is achievable by QIM under AWGN was first derived in [5]. In most cases quantization is implemented to some
%U http://www.hindawi.com/journals/ijdmb/2014/910808/