Dusan Levicky

A novel method of image steganography in DWT domain

In this paper, we present a novel steganographic method for embedding of secret data in still grayscale image. In order to provide large capacity of the secret data while maintaining good visual quality of stego-image, the embedding process is performed in transform domain of Discrete Wavelet transform (DWT) by modifying of transform coefficients in an appropriate manner. In addition, the proposed method do not require original image for successful extraction of the secret information. The experimental results show that the proposed method provides good capacity and excellent image quality.

Digital watermarking of uncompressed video in spatial domain

Digital watermarking has been proposed as a method for discouragement of illegal copying and distribution of copyrighted material. Currently proposed algorithms of digital watermarking in the context of the video are robust against unintentional attacks, but many of them do not protect enough against malicious attacks. This paper presents a new video watermarking system with improved robustness, which is based on spread spectrum technique. Finally, we also present results, which verify the enhanced robustness of proposed system against malicious and non-malicious attacks.

Multimodal biometric authentication using speech and hand geometry fusion

The paper presents biometric security system based on fusion of voice print and hand geometry recognition technologies. Speaker recognition works as text independent and is designed to verify a person using a short utterance. GMM method is used for speaker modeling and GMM-UBM classifier is used for process of matching. Hand geometry technology uses 21 extracted features from image of userpsilas hand and Euclidian distance for recognition. Information fusion in the multimodal system is performed at the matching score level, where scores obtained from matchers are combined using different normalization techniques and fusion rules. Multimodal system after fusion achieved 82.78% reduction in equal error rate over the better of the two independent systems.

Steganography systems by using CDMA techniques

In this paper, we present a novel method called Code Book in steganography system based on CDMA (Code Division Multiple Access) techniques having regard to perceptibility of stego-image. These techniques and their variations are widely used in radio telecommunication systems. As it will be shown later, aptly imposed features of CDMA techniques are in consonance with imperatives claimed upon steganography systems.

Log-polar Mapping in Robust Digital Image Watermarking

The geometrical attacks are still open problem for many digital watermarking algorithms used in present time. Most of geometrical attacks can be described by using affine transforms. This article deals with digital watermarking in images robust against the affine transformations. The new approach to improve robustness against geometrical attacks is presented. The discrete Fourier transform and log-polar mapping is used for watermark embedding and for watermark detection. Some attacks against the embedded watermarks are performed and the results are given.

Robust frame by frame video watermarking resistant against collusion attacks

Many frame by frame video watermarking methods where proposed, but only a few of them are robust against collusion attacks. These attacks can be easily conducted and their result is an unmarked video. In this paper a frame by frame watermarking method is proposed, which is robust against unintentional attacks, attacks of frame dropping, frame swapping and collusion attacks. Experimental results are also included to verify the robustness of the proposed method against some of the above mentioned attacks.

Robust image watermarking based on the synchronization template

Digital watermarking is a potential effective method for authentication and ownership rights protection. The digital watermark is hidden information added into the multimedia. This paper presents robust digital watermarking in images. One robust digital watermarking based on the synchronization template is presented and some experimental results are presented too.

Robust digital watermarking in color images

Digital watermarking is a potential effective method for authentication and ownership rights protection. The digital watermark is hidden information added into the multimedia. This paper presents one watermarking method for the color images robust against geometrical attacks. The detailed description of this method is given and some experiments by using the set of different attacks are performed.

Image steganography based on combination of YC b C r color model and DWT

Steganography is the process of implanting secret message in a cover data without causing degradation neither to the cover information nor to the secret message implanted in the cover data. Most of the steganographic techniques are applied on images, texts, and protocols. In this paper a novel algorithm of image steganography is proposed to implant a secret text message into a cover image using YCbCr color space model and 2D Haar Discrete Wavelet Transform. In this proposed technique, input text in ASCII code is encrypted by AES what ensures, that the relative letter frequency of a plain text secret message will be disturbed. Proposed technique also solves conversion between color space models RGB and YCbCr in spite of modification in component Cb by the secret message. This step allows extracting of secret message without errors what is a very important characteristic, because change of only one bit causes extracting of different character. Performance of the proposed algorithm has been gauged by the peak signal to noise ratio (PSNR) and mean square error (MSE) for the stego image.

Usage of different color models in robust digital watermarking

Digital watermarking represents a potential effective method for authentication and ownership rights protection in all kind of multimedia. Digital watermark is hidden information added into the content of multimedia. This paper presents one watermarking method for the color images robust against geometrical attacks. The detailed description of this method is given and some experiments by using the set of different attacks are performed. In experiment different color models were used and in experiments advantages and drawbacks of these color models were tested.