Wei-Liang Tai

Multilevel reversible data hiding based on histogram modification of difference images

Reversible data hiding has drawn considerable attention in recent years. Reversibility allows original media to be completely recovered from marked media without distortion after embedded message has been extracted. In this paper we propose a multilevel reversible data hiding scheme based on the difference image histogram modification that uses the peak point to hide messages. Through a joint imperceptibility and hiding capacity evaluation, we show that our proposed scheme uses a multilevel hiding strategy to achieve large hiding capacity and keep distortion low. Performance comparisons with other existing reversible hiding schemes are provided to demonstrate the validity of our proposed scheme.

Reversible hiding in DCT-based compressed images

This paper presents a lossless and reversible steganography scheme for hiding secret data in each block of quantized discrete cosine transformation (DCT) coefficients in JPEG images. In this scheme, the two successive zero coefficients of the medium-frequency components in each block are used to hide the secret data. Furthermore, the scheme modifies the quantization table to maintain the quality of the stego-image. Experimental results also confirm that the proposed scheme can provide expected acceptable image quality of stego-images and successfully achieve reversibility.

A Reversible Data Hiding Scheme Based on Side Match Vector Quantization

Many researchers have studied reversible data hiding techniques in recent years and most have proposed reversible data hiding schemes that guarantee only that the original cover image can be reconstructed completely. Once the secret data are embedded in the compression domain and the receiver wants to store the cover image in a compression mode to save storage space, the receiver must extract the secret data, reconstruct the cover image, and compress the cover image again to generate compression codes. In this paper, we present a reversible data hiding scheme based on side match vector quantization (SMVQ) for digitally compressed images. With this scheme, the receiver only performs two steps to achieve the same goal: extract the secret data and reconstruct the original SMVQ compression codes. In terms of the size of the secret data, the visual quality, and the compression rate, experimental results show that the performance of our proposed scheme is better than those of other information hiding schemes for VQ-based and SMVQ-based compressed images. The experimental results further confirm the effectiveness and reversibility of the proposed scheme

Four-scanning attack on hierarchical digital watermarking method for image tamper detection and recovery

In a recent paper presented by Lin et al., a block-based hierarchical watermarking algorithm for digital images is proposed. It adopts parity check and the intensity-relation check to conduct the experiment of image tamper detection. Their experimental results indicate that the precision of tamper detection and localization is 99.6% and 100% after level-2 and level-3 inspections, respectively. The proposed attacks demonstrate that this watermarking algorithm is fundamentally flawed in that the attacker can tamper a watermarked image easily without being detected. In this paper, a four-scanning attack aimed to Lin et al.s watermarking method is presented to create tampered images. Furthermore, in case they use encryption to protect their 3-tuple-watermark, we proposed a blind attack to tamper watermarked images without being detected. Experimental results are given to support and enhance our conclusions, and demonstrate that our attacks are successful in tampering watermarked images.

A reversible data hiding scheme with modified side match vector quantization

Indices are modified so that the secret data can be hidden into the index-based cover image, and thereby the problem of the stego-image quality degradation occurs. If the stego-image quality degradation problem can be solved enabling the receiver to reconstruct the original indices after extracting the hidden secret data from the index-based stego-image, then the compressed cover image can be used repeatedly by different users. To achieve our goal, in this paper, a reversible data-hiding scheme based on a modified side match vector quantization (SMVQ) technique is proposed. Our experimental results confirm the effectiveness and the reversibility of the proposed scheme.

A Multipurpose Wavelet-Based Image Watermarking

To address copyright protection and content authentication, researchers have proposed various digital watermarking methods. In this paper, an improved, multipurpose method is proposed where the authentication watermark and the robust watermark are embedded in the wavelet transform domain. Through a series of experiment, supportive evidence is provided to demonstrate the proposed method being effective in image authentication and pre-empting image processing attacks

Secret Hiding Using Side Match Vector Quantization

Since side match vector quantization (SMVQ) provides better image quality of reconstructed image and compression bit rate than vector quantization (VQ) does, it becomes another choice to compress the transmitting images when the bandwidth is limited. To expand the cover media for transmitting confidential information, we propose a novel data hiding scheme which embeds secret data into the SMVQ-compressed image. In terms of the payload capacity, the visual quality, and the compression rate, experimental results confirm that the performances of our scheme are better than that of other information hiding schemes for VQ-based and SMVQ-based compressed images. In addition, the embedded secret data can be extracted from the stego-image without referencing the original cover image.