Da-Chun Wu

A steganographic method for images by pixel-value differencing

A new and efficient steganographic method for embedding secret messages into a gray-valued cover image is proposed. In the process of embedding a secret message, a cover image is partitioned into non-overlapping blocks of two consecutive pixels. A difference value is calculated from the values of the two pixels in each block. All possible difference values are classified into a number of ranges. The selection of the range intervals is based on the characteristics of human visions sensitivity to gray value variations from smoothness to contrast. The difference value then is replaced by a new value to embed the value of a sub-stream of the secret message. The number of bits which can be embedded in a pixel pair is decided by the width of the range that the difference value belongs to. The method is designed in such a way that the modification is never out of the range interval. This method provides an easy way to produce a more imperceptible result than those yielded by simple least-significant-bit replacement methods. The embedded secret message can be extracted from the resulting stego-image without referencing the original cover image. Moreover, a pseudo-random mechanism may be used to achieve secrecy protection. Experimental results show the feasibility of the proposed method. Dual statistics attacks were also conducted to collect related data to show the security of the method.

Data hiding in images via multiple-based number conversion and lossy compression

A novel and easy method to embed any form of secret messages into a cover image with controlled distortion is proposed. Any lossy image compressor may be applied first to a cover image to produce a lossily-processed result as the basis for embedding data in the cover image. The stego-image is produced by embedding data in each pixel of a cover image by changing its gray value without excessing the range of the gray value difference of the corresponding pixels of the cover image and its lossily-processed one. The quantity of distortion that is caused by embedding data is never in excess of that is caused by the lossy compressor. A multiple-based number system is proposed to convert the information in the secret bit stream into values to be embedded in the choosing pixels of the cover image. Pseudo-random mechanisms may be used to achieve cryptography. It is found from experiments that the values of the peaks of the signal-to-noise ratio of the stego-images are larger than those yielded by the chosen compressor, which means that the distortion in the embedding result is more imperceptible than that in the compressed one.

A novel 3D mesh compression using mesh segmentation with multiple principal plane analysis

This paper proposes a novel scheme for 3D model compression based on mesh segmentation using multiple principal plane analysis. This algorithm first performs a mesh segmentation scheme, based on fusion of the well-known k-means clustering and the proposed principal plane analysis to separate the input 3D mesh into a set of disjointed polygonal regions. The boundary indexing scheme for the whole object is created by assembling local regions. Finally, the current work proposes a triangle traversal scheme to encode the connectivity and geometry information simultaneously for every patch under the guidance of the boundary indexing scheme. Simulation results demonstrate that the proposed algorithm obtains good performance in terms of compression rate and reconstruction quality.

Embedding of any type of data in images based on a human visual model and multiple-based number conversion

A novel approach to embedding any type of digital data into a cover image is proposed, which utilizes a human visual model to guarantee that the modification of the cover image is imperceptible. A quantized contrast function based on the model is constructed first. The gray values of each 3 3 sub-image of the cover image are used to compute, using the function, a range of gray levels with the same contrast as that of the central pixel of the sub-image. The embedding process proceeds by replacing the gray value of the central pixel by one of the values in the range. This guarantees that the changes be imperceptible. The data to be embedded is treated as a binary stream and is partitioned into a number of sub-streams. A multiple-base number conversion mechanism is used to convert each sub-stream of data into values which are then embedded in the central pixels of sub-images. The embedded data can be extracted out from the resulting stego-image without referencing the original image. Experimental results show that the proposed method is feasible. ” 1999 Published by Elsevier Science B.V. All rights reserved.

A novel block-based authentication technique for binary images by block pixel rearrangements

A novel block-based binary image authentication technique is proposed. The authentication signals of each 9times9 image block are placed in a selected 3times3 block within the 9times9 block. The authentication signal contains a certain relationship contributed by the standard deviation values of the other eight 3times3 blocks. Authentication signals are generated by rearranging the pixels in the selected 3times3 block. The rearrangement is designed according to a property of inverse halftoning to keep the visual change in the selected block imperceptible. By comparing the arrangement of the block pixels in a suspicious image with the extracted authentication signals, the fidelity and integrity of the image can be verified

A Parallel CBIR Implementation using Perceptual Grouping of Block-Based Visual Patterns

This paper proposes a parallel solution to retrieve images from distributed data sources using perceptual grouping of block-based visual patterns. The method of grouping visual patterns into image model based on generalized Hough transform is one of the most powerful techniques for image analysis. However, real-time applications of this method have been prohibited due to the computational intensity in similarity searching from a large centralized image collection. A query object is decomposed into non-overlapped blocks, where each of them is represented as a visual pattern obtained by detecting the line edge from the block using the moment-preserving edge detector. A voting scheme based on generalized Hough transform is proposed to provide object search method, which is invariant to the translation, rotation, scaling of image data. In this work, we describe a heterogeneous cluster-oriented CBIR implementation. First, the workload to perform an object search is analyzed, and then, a new load balancing algorithm for the CBIR system is presented. Simulation results show that the proposed method gives good performance and spans a new way to design a cost-effective CBIR system.

Information Hiding in Standard MIDI Files Based on Velocity Reference Values

This paper proposed a novel method to embed information in SMFs (Standard MIDI Files) by slightly adjusting the velocity values of notes. First, this method uses the velocity values of the first note of strong beat, the first of weak beat, and the first second-strong beat with non-zero velocity value in a measure as the referencing values for velocity of other notes in the same measure. Then, the data are embedded in the velocity values of notes excluding the notes with the referencing values. The method uses the difference between the velocity value of each note and its corresponding reference value to decide the number of bits which can be used for embedding data in each note. The proposed method limits the changes of the velocity value of each note to its original value and its corresponding reference value during the data embedding. It can avoid the differences from the original music being heard due to the velocity values excessive change. In addition, the proposed method can also embed data with- out changing the file sizes of the SMFs. It can also avoid attracting attention. The experimental results show the feasibility of the proposed method.

Reversible data hiding in Standard MIDI Files by adjusting delta time values

In this paper, an effective method of hiding information in Standard MIDI Files (SMF) is presented. The method simultaneously shifts the binary representations of both the division value and non-zero delta time values in a MIDI file left in order to hide information, and embeds secret information in the bits of the non-zero delta time values produced by the left shifting. The number of left shift bits is in accordance with both the tolerance of beat-changing and the size of the secret information to be embedded. Experimental results show that the proposed method is not only able to embed secret information in Standard MIDI Files without influencing their playing quality, but is also able to recover the original MIDI files without distortion after the hidden data have been extracted.

Information Hiding in EPUB Files by Rearranging the Contents of CSS Files

With the recent rapid development of information technology and mobile devices, e-books have come to have a significant influence on peoples reading habits. However, with the widespread use of digital texts, issues surrounding copyright protection have arisen. EPUB is currently the most widely used e-book format. This paper proposes an information hiding technology to hide messages in EPUB files. These hidden messages can be used to protect the copyright of e-books or to transmit secret information. The method embeds secret messages into EPUB files using the lexicographical order for coding information and rearranging the selector rules and their property declarations in CSS files. It also makes use of the fact that selector rules in a CSS file need not be referred by its associate XHTM files in order to insert fake selector rules into the CSS file to increase hiding capacity. The proposed hiding method does not change the outward appearance of EPUB documents in any way, so it is imperceptible. According to experiments conducted, the hiding method is feasible and effective.

3D Triangular Mesh Watermarking for Copyright Protection Using Moment-Preserving

A new watermarking scheme on 3D triangular mesh models is proposed. Watermarks are embedded by modifying a subset of carefully selected edge vertices in order to resist attacks. A local geometrical disturbance on the selected edge vertices is used to embed the information without destroying the local connectivity. Edge vertices are detected using the proposed 3D moment-preserving technique. Edge vertices quantize into multiple classes where each of them is used to embed a watermark bit. Experimental results show that the proposed scheme is robust in resisting common attacks.