Showing papers by "Wen-Hsiang Tsai published in 2004"
TL;DR: A novel approach to secret image sharing based on a (k, n)-threshold scheme with the additional capabilities of steganography and authentication with the capability of authenticating the fidelity of each processed camouflage image, called a stego-image is proposed.
454 citations
TL;DR: Wang et al. as discussed by the authors proposed a new method for data hiding in palette images with security protection by color ordering and mapping, as well as parameter randomization, which is based on the use of a new type of colorordering relationship, from which a color-mapping function is defined with binary values as output.
Abstract: Palette images are widely used in multimedia and Internet applications. In this paper, a new method for data hiding in palette images with security protection by color ordering and mapping, as well as parameter randomization, is proposed. First, image pixels are classified as data embeddable or nonembeddable, and only the former ones are used to embed secret data. The proposed idea of data hiding is based on the use of a new type of color-ordering relationship, from which a color-mapping function is defined with binary values as output. When a secret data bit is to be embedded, a data-embeddable pixel is selected, and its color is adjusted to make the output of the color-mapping function equal to the secret bit value. The embedded secret data can be extracted correctly and quickly from the resulting stego-image by merely inspecting the outputs of the color-mapping function. Indetectability of the secret information embedded by the proposed method is also analyzed and confirmed. Furthermore, a number of possible security enhancement measures based on parameter randomization in the data-embedding process are proposed to protect the hidden data in the stego-image. The randomization effect is created by the use of a secret key and a number of random number-generating functions. The proposed data hiding method was tested with a variety of palette images. The experimental results show that secret data can be embedded and extracted successfully without producing visual artifacts in the cover image. A good balance between stego-image quality and data-embedding capacity can be achieved, which proves the efficiency and feasibility of the proposed method for practical applications.
66 citations
21 Mar 2004
TL;DR: A novel method for construction of perspective and panoramic images from omni-images taken from hypercatadioptric cameras for visual surveillance, called 8-directional-regions interpolation, to interpolate the unfilled pixels' coordinates in the image yielded in the first step to complete the image construction work.
Abstract: A novel method for construction of perspective and panoramic images from omni-images taken from hypercatadioptric cameras for visual surveillance is proposed. The constructing work includes two major steps: unwarping of the omni-image into a rectangularly tessellated perspective or panoramic image, followed by interpolation of the coordinates of the image pixels which are unfilled in the first step. For the former step, techniques for combining the uses of a back-projection method and some geometric relations within the camera system to yield a forward-projection effect to accomplish the unwarping task are employed. And for the latter step, a novel scheme, called 8-directional-regions interpolation, to interpolate the unfilled pixels' coordinates in the image yielded in the first step to complete the image construction work is proposed. Good experimental results are also included to show the feasibility of the proposed method.
14 citations
30 Jun 2004
TL;DR: A novel block-based binary image authentication technique that compares 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.
Abstract: 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
9 citations
Journal Article•
3 citations
TL;DR: In this paper, a robust trajectory planning method for vision-based autonomous land vehicle (ALV) guidance by target following using a visual field model is proposed, which aims to guide the ALV to achieve the goal that the targeted person will always appear in the image.
Abstract: We propose a robust trajectory planning method for vision-based autonomous land vehicle (ALV) guidance by target following using a visual field model. The proposed trajectory planning method aims to guide the ALV to achieve the goal that the targeted person will always appear in the image. It is found in this study that the goal can be achieved if three visual contact constraints in the visual field model are satisfied. The first constraint postulates that the target has appeared in the image. The second constraint asks that the vehicle head at the next position points straight towards to the target's current position. The third constraint sets bounds between the next position of the ALV and the current position of the target. A formula for the trajectory of the vehicle that satisfies the second visual contact constraint is derived. The steps for generating a speed and a turn angle of the ALV for real-time navigation are described as a trajectory-planning algorithm. Finally, the approach is tested on a real ALV and successful navigation sessions confirm the feasibility and the robustness of the approach.