Jen-Tse Wang

A Novel Chaos Sequence Based 3D Fragile Watermarking Scheme

Watermarking is a very important technique for protecting the authorization of digital content, such as, still images, video streams, audio streams and 3D models. In fragile watermarking, the watermark is used for authentication and the hash function is applied to achieve the verification tasks in most fragile watermarking schemes for 3D models. In this paper, a novel Chaos sequence based fragile watermarking scheme for 3D models in spatial domain is proposed. The proposed scheme employs a Chaos sequence generator to generate a Chaos sequence, which is used to generate the embedded watermark. Instead of the hash function, the tampering region can be verified and located by the Chaos sequence based watermark check. The Chaos sequence based watermark is embedded to achieve both the authentication and verification. Experimental results show that the proposed scheme can achieve authentication of the original model and tampering detection of the stego model with insignificant visual distortion.

Hamming Code Based Watermarking Scheme for 3D Model Verification

The technique of 3D modeling and the Internet progress quickly, the issue of the copyright of 3D models has become more and more important. There is a public hamming code based fragile watermarking technique proposed in this paper. The target of this article is to verify the authenticity of the model. An adaptive watermark is generated by using hamming code which extract some specific data from each cover model. The watermark is then embedded into the model. Using hamming procedure to generate watermark do not need original model and watermark information for verification in extracted stage. Experimental results show that the embedding rate achieve 100%. And the distortion of every stego model can be controlled below 10-10.

Error Detecting Code Based Fragile Watermarking Scheme for 3D Models

The security problem of the watermark verification task is one of the most important issues in real world application. Most published 3D fragile watermarking schemes employed the verification task only mentioned one method which uses the hash function. It is hard to implement these fragile watermarking schemes in real world application due to the high collision characteristic of the hash function. To achieve the verification task, the concept of error detecting code is applied. An error detecting code based reversible fragile watermarking scheme for 3D models in spatial domain is proposed in this paper. The proposed scheme is employed to watermarking a 3D model by using the reversible quantization index modulation technique. The verification bits are absent in the proposed scheme, and the verification task is achieved by the authentication of the error detecting code based watermark. Experimental results show that the damaged watermark can be detected and the distortion can be controlled by the key value setting.

Contrast Enhancement in Palm Bone Image Using Quad-Histogram Equalization

Histogram equalization is widely used for contrast enhancement of given images. The traditional histogram equalization technique usually results in extreme contrast enhancement, which leads to an unnatural look. In this paper, the mean-variance analysis method is employed to partition the grey scale image into four sub images for individual image. A quad-histogram equalization technique is proposed to enhance the contrast of the palm bone X-ray radiographs. Experimental results using the proposed method show that our algorithm is better than the global histogram equalization (GHE) technique and brightness preserving bi-histogram equalization (BBHE) technique.

A spherical coordinate based fragile watermarking scheme for 3D models

In this paper, a new spherical coordinate based fragile watermarking scheme is proposed. At first, the three dimensional (3D) model is translated from the Cartesian coordinate system to the spherical coordinate system. Then the quantization index modulation technique is employed to embed the watermark into the r coordinate for authentication and verification. By adapting the quantization index modulation technique together with some keys in the spherical coordinate system, the distortion is controlled by the quantization step setting. Experimental results show that both the 100% embedding rate and low distortion can be achieved simultaneous in the proposed method. Moreover, the causality, convergence and vertex reordering problems can be overcome.

Reversible fragile watermarking scheme for three-dimensional models

Watermarking is a very important technique for protecting the authorization of digital content, such as still images, video streams, audio streams, and 3-D models. Most fragile watermarking schemes for 3-D models are not reversible. Published reversible or irreversible fragile watermarking schemes for 3-D models have many drawbacks, such as the causality problem, not being blind, or being unable to locate changed regions. To overcome these drawbacks, a reversible fragile watermarking scheme for 3-D models in spatial domain is proposed. Principal component analysis (PCA) is employed to produce the PCA coordinate system and make the system robust against similarity transformation attacks. PCA, together with a novel interval embedding technique, provide the blind reversibility of the proposed scheme. Intervals larger than a threshold and smaller than another threshold are adopted as legitimate to avoid large distortion. Moreover, experimental results show that the proposed scheme can overcome the causality, convergence, and confusion problems; provide both tampering detection and better embedding rate and requiring a small key size.

Some properties of involution binary relations

This paper aims to investigate properties of involution binary relations, which are some particular binary relations. We study the concepts of involution spanning sets and give some examples related to different involution binary relations. Moreover, some relationships among the involution independent sets, codes, and involution codes are studied when the mapping function is either a morphic or an antimorphic involution of

An OFB-Based Fragile Watermarking Scheme for 3D Polygonal Meshes

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