Huang Jiwu

A DWT-based image watermarking algorithm

In this paper, a new embedding strategy for DWT-based watermarking is proposed. Different from the existing watermarking schemes in which low frequency coefficients are explicitly excluded from watermark embedding, we claim that watermarks should be embedded in the low frequency subband firstly, and the remains should be embedded in high frequency subbands according to the significance of subbands. We also claim that different embedding formula should be applied on the low frequency subband and high frequency subbands respectively. Applying this strategy, an adaptive algorithm incorporating the feature of visual masking of human vision system into watermarking is proposed. In the algorithm, a novel method to classify wavelet blocks is presented. The experimental results demonstrate that the watermarks generated with the proposed algorithm are invisible and robust against noise and commonly used image processing techniques.

A high capacity distortion-free data hiding algorithm for palette image

Data hiding techniques have extensive applications and have attracted much attention. However, one common drawback of virtually all current data hiding methods is the fact that the host image is inevitably and permanently distorted by some small amount of noise due to data hiding itself Although the distortion is often quite small, it may not be acceptable for medical or military images. For these applications, the stego-image cannot have any distortion, a high capacity distortion-free data hiding algorithm for the palette image is proposed in this paper. By utilizing the color redundancy in the host image, the algorithm can embed large amount of information, which usually can reach more than 10% of size of the host image. Meanwhile, it can be guaranteed that no distortion is introduced to the host image during data hiding process.

Steganalysis of stochastic modulation steganography

Stochastic modulation steganography embeds secret message within the cover image by adding stego-noise with a specific probabilistic distribution. No method is known to be applicable to the estimation of stochastic modulation steganography. By analyzing the distributions of the horizontal pixel difference of images before and after stochastic modulation embedding, we present a new steganalytic approach to accurately estimate the length of secret message in stochastic modulation steganography. The proposed method first establishes a model describing the statistical relationship among the differences of the cover image, stego-image and stego-noise. In the case of stego-image-only steganalysis, rough estimate of the distributional parameters of the cover image’s pixel difference is obtained with the use of the provided stego-image. And grid search and Chi-square goodness of fit test are exploited to estimate the length of the secret message embedded with stochastic modulation steganography. The experimental results demonstrate that our new approach is effective for steganalyzing stochastic modulation steganography and accurately estimating the length of the secret message.

Watermarking Parameters Feasible Region Model

In this paper, the effectiveness and the parameters space of the public watermark algorithm based on modulus of congruence are considered, and the model of the watermark effectiveness feasible region is proposed. The main contributions of the paper are as follows: (1) by distinction parameter, the relations of embedding, extracting watermark and distinction parameter are established, and the necessary and sufficient conditions of lossless watermark detecting or extracting and its parameters feasible region are presented, (2) by parameters feasible region, the control conditions of the watermark robustness and fragileness are given, and the optimality of distinction parameter of the algorithm is proved, (3) under Gaussian noises attack, the mathematical model of the relations of the lossy watermark BER (bit error rate), attack strength and embedding strength is proposed