Reversible watermarking enables the embedding of useful information in a host signal without any loss of host information. Tian's difference-expansion technique is a high-capacity, reversible method for data embedding. However, the method suffers from undesirable distortion at low embedding capacities and lack of capacity control due to the need for embedding a location map. We propose a histogram shifting technique as an alternative to embedding the location map. The proposed technique improves the distortion performance at low embedding capacities and mitigates the capacity control problem. We also propose a reversible data-embedding technique called prediction-error expansion. This new technique better exploits the correlation inherent in the neighborhood of a pixel than the difference-expansion scheme. Prediction-error expansion and histogram shifting combine to form an effective method for data embedding. The experimental results for many standard test images show that prediction-error expansion doubles the maximum embedding capacity when compared to difference expansion. There is also a significant improvement in the quality of the watermarked image, especially at moderate embedding capacities

Expansion Embedding Techniques for Reversible Watermarking

In this letter, we present a reversible data hiding scheme based on histogram modification. We exploit a binary tree structure to solve the problem of communicating pairs of peak points. Distribution of pixel differences is used to achieve large hiding capacity while keeping the distortion low. We also adopt a histogram shifting technique to prevent overflow and underflow. Performance comparisons with other existing schemes are provided to demonstrate the superiority of the proposed scheme.

Reversible Data Hiding Based on Histogram Modification of Pixel Differences

Digital watermarking applications of digital watermarking digital watermarking for still images digital watermarking for audio data digital watermarking for other media attacks, benchmarks and standardization other content protection mechanisms integrated content protection solutions conclusion.

Techniques and Applications of Digital Watermarking and Content Protection

This paper presents a robust watermarking algorithm with informed detection for 3D polygonal meshes. The algorithm is based on our previous algorithm [22] that employs mesh-spectral analysis to modify mesh shapes in their transformed domain. This paper presents extensions to our previous algorithm so that (1) much larger meshes can be watermarked within a reasonable time, and that (2) the watermark is robust against connectivity alteration (e.g., mesh simplification), and that (3) the watermark is robust against attacks that combine similarity transformation with such other attacks as cropping, mesh simplification, and smoothing. Experiment showed that our new watermarks are resistant against mesh simplification and remeshing combined with resection, similarity transformation, and other operations..

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A Frequency‐Domain Approach to Watermarking 3D Shapes

In this paper, we present a new scheme for digital steganography of three-dimensional (3-D) triangle meshes. This scheme is robust against translation, rotation, and scaling operations. It is based on a substitutive procedure in the spatial domain. The key idea is to consider a triangle as a two-state geometrical object. We discuss its performance in terms of capacity, complexity, visibility, and security. We validate the use of a principal component analysis (PCA) to make our scheme signal-dependent in the line of second generation watermarking scheme. We also define a simple specific metric for distortion evaluation that has been validated by many tests. We conclude by giving some other solutions, including open steganographic schemes that could be derived from the basic ideas presented here.

Data hiding on 3-D triangle meshes

We describe a Digital Watermarking system dedicated for embedding watermarks into 3D polygonal models. The system consists of three watermarking algorithms, one named Vertex Flood Algorithm (VFA) suitable for embedding fragile public readable watermarks with high capacity and offering a way of model authentication, one realizing affine invariant watermarks, named Affine Invariant Embedding (AIE) and a third one, named Normal Bin Encoding (NBE) algorithm, realizing watermarks with robustness against more complex operations, most noticeably polygon reduction. The watermarks generated by these algorithms are stackable. We shortly discuss the implementation of the system, which is realized as a 3D Studio MAX plugin.

Towards Blind Detection of Robust Watermarks in Polygonal Models

This paper presents a watermarking algorithm suitable for embedding private watermarks into three dimensional polygon based models. The algorithm modifies the models normal distribution to store information solely in the geometry of the model. The watermarks show significant robustness against mesh simplifying methods.

Watermarking of 3D-polygon-based models with robustness against mesh simplification

We present a scheme for embedding secret or public readable watermarks into 3D models consisting of polygonal or NURBS surfaces. The scheme realizes affine invariant watermarks by displacing vertices (control points) and satisfies constraints regarding maximum tolerated vertex movements or, in the NURBS case, differences of original and watermarked surfaces. The algorithm uses the volume of two tetrahedrons as an embedding feature. The scheme described can be stacked on a more robust scheme allowing transmission of labeling information to the user or increasing blind detection capabilities of the underlying scheme. The paper makes two major contributions, both driven by real world requirements: The first one is a technique to cope with reduced precisions of vertex coordinates. Real world modeling applications represent vertex coordinates with single floating point precision. Vertex coordinates in VRML scenes are represented by 6 decimal digits or even less. Mesh compression schemes may quantize vertex coordinates to even below precision of 4 decimal digits. The second contribution of this paper is a general technique for reducing processing time of watermark (label) extraction satisfying impatient users and enhancing robustness with respect to affine transformations and, in particular, vertex randomization attacks. The technique is based on simplifying the mesh applying edge collapses prior to watermark embedding and retrieval. The technique depends on a consistent order of vertices in embedding and retrieval process. We sketch possible extensions of the proposed scheme.

Affine Invariant Watermarks for 3D Polygonal and NURBS Based Models

We propose a robust non-blind watermarking algorithm based on direct free form deformations and applicable to smooth (organic) meshes. The algorithm does generate "low frequent" smooth deformations. The second main contribution of this paper is a registration method capable of handling affine transformations in cases where meshes do not suffer from cropping. The method is an extension of results from Blake and Marinos [1] to the 3D dimensional case. We use this method as a preprocessing step of a conventional registration algorithm (capable of handling rigid transformations plus uniform scaling). We are therefore able to automatically retrieve watermarks from copies differing from the original by one global affine transformation and of course additional complex operations, the watermarking method is robust against, such as polygon simplification, subdivision surfaces, uniform- or gaussian distributed noise. We present experiments on robustness of watermarks and performance of the proposed registration technique.

Robust Watermarking and Affine Registration of 3D Meshes

Digital watermarking has become an accepted technology for enabling multimedia protection schemes. Based on the introduced media independent protocol schemes for invertible data authentication in references 2, 4 and 5 we discuss the design of a new 3D invertible labeling technique to ensure and require high data integrity. We combine digital signature schemes and digital watermarking to provide a public verifiable integrity. Furthermore the protocol steps in the other papers to ensure that the original data can only be reproduced with a secret key is adopted for 3D meshes. The goal is to show how the existing protocol can be used for 3D meshes to provide solutions for authentication watermarking. In our design concept and evaluation we see that due to the nature of 3D meshes the invertible function are different from the image and audio concepts to achieve invertibility to guaranty reversibility of the original. Therefore we introduce a concept for distortion free invertibility and a concept for adjustable minimum distortion invertibility.

Oliver Benedens

Papers

Towards Blind Detection of Robust Watermarks in Polygonal Models

Watermarking of 3D-polygon-based models with robustness against mesh simplification

Affine Invariant Watermarks for 3D Polygonal and NURBS Based Models

Robust Watermarking and Affine Registration of 3D Meshes

Invertible authentication for 3D meshes