Showing papers by "Wen-Hsiang Tsai published in 2003"

A new approach to authentication of binary images for multimedia communication with distortion reduction and security enhancement

Abstract: A new approach to binary image authentication in multimedia communication with distortion reduction and security enhancement is proposed. Special codes are embedded into the blocks of given images and verified to accomplish the authentication purpose. Enhancement of security in detecting tampered images is achieved by randomly generating the codes and embedding them into randomly selected locations in the image blocks. The reduction of image distortion coming from pixel value replacement in code embedding is carried out by allowing multiple locations for embedding the codes. Security analysis and experimental results are also included to show the effectiveness of the proposed approach.

Secret image sharing with capability of share data reduction

Abstract: A novel approach to secret image sharing based on a (k,n)-threshold scheme with the additional capability of share data re- duction is proposed. A secret image is first transformed into the fre- quency domain using the discrete cosine transform (DCT), which is ap- plied in most compression schemes. Then all the DCT coefficients except the first 10 lower frequency ones are discarded. And the values of the 2nd through the 10th coefficients are disarranged in such a way that they cannot be recovered without the first coefficient and that the inverse DCT of them cannot reveal the details of the original image. Finally, the first coefficient is encoded into a number of shares for a group of secret- sharing participants and the remaining nine manipulated coefficients are allowed to be accessible to the public. The overall effect of this scheme is achievement of effective secret sharing with good reduction of share data. The scheme is thus suitable for certain application environments, such as the uses of mobile or handheld devices, where only a small amount of network traffic for shared transmission and a small amount of space for data storage are allowed. Good experimental results proving the feasibility of the proposed approach are also included. © 2003 Society

Location estimation and trajectory prediction of moving lateral vehicle using two wheel shapes information in 2-D lateral vehicle images by 3-D computer vision techniques

Abstract: A novel approach to location estimation and trajectory prediction of moving lateral vehicle locations for driving assistance using wheels shape information in single 2-D vehicle images by 3-D computer vision techniques is proposed. The location scheme is supposed to be performed on a vehicle with a camera mounted on the front bumper. An analytical solution is applied to estimate the location of the lateral vehicle. Firstly, the normal vectors of the car wheels in the camera coordinate system as well as the projections of the wheel centers in the image plane are derived. Then orientation angle of the lateral vehicle with respect to the driving vehicle is derived from the two vectors. Next, the image projections of the contact points of the wheels with the ground are detected. Finally, the image positions of the contact points are used to determine the 3D relative position of the moving vehicle with respect to the camera coordinate system by the back-projection principle. After the location of a moving lateral vehicle is obtained, a new approach is proposed to predict the trajectory of a lateral vehicle by using the spatial information of the two wheels in a single image. Real images are tested and experimental results show the effectiveness of the proposed approaches. The results are useful for car driving assistance and vehicle collision avoidance.

Copyright Protection and Authentication of Grayscale Images by Removable Visible Watermarking and Invisible Signal Embedding Techniques: A New Approach*

Abstract: A novel method for copyright protection and authentication of grayscale images is proposed. The involved techniques include a human visual model, least significant bit replacement, and reversible pixel color adjustment. These techniques are integrated effectively to embed a visible watermark and authentication signals into the single grayscale channel of the image. The copyright of the image can be proved by extracting the embedded watermark. And the integrity of the image can be proved by verifying the existence of the embedded authentication signals. Besides, the embedded visible watermark can be removed, if desired, so that only the watermarked image need be kept, providing an advantage of storage space saving. Some experimental results are shown to prove the feasibility of the proposed method.

Hiding binary images behind noise with authentication capability: a new approach to covert communication

Abstract: A new approach to hiding secret binary images behind noise images for covert communication with a capability of secret authentication is proposed. A secret image to be transmitted is transformed into a random noise image at a sender site with a given key, with the aim of both covering the secret and cheating illicit interceptors. Authentication bits are also embedded imperceptibly in the noise image. At the receiver site, the secret image is recovered from the noise image with the same key and verified by checking the existence of the authentication bits. Experimental results show the feasibility of the approach for real applications.

Watermarking approach to embedded signature- based authentication by channel statistics

Abstract: Embedded signature-based authentication is a highly promis- ing watermarking method for solving high-level authentication problems. This work proposes such a watermarking approach using channel sta- tistics evaluated from a reference watermark. The basic concept is to consider the problem to be an example of communications with side information, which is the reference watermark embedded in the host with the signature at the sender site. At the receiver site, the reference wa- termark is first extracted to determine channel statistics, which are used to generate information about signature reliability. Three kinds of infor- mation are derived, including a reliability measure, an entropy measure, and an authenticated signature. Experimental results establish that the measures of reliability and uncertainty are meaningful, and that the em- bedded signature can survive high-quality JPEG compression and ma- nipulations such as negation, cropping, replacement, and modification. © 2003 Society of Photo-Optical Instrumentation Engineers.