Yi-Chong Zeng

A Novel Image Recovery Algorithm for Visible Watermarked Images

A novel image recovery algorithm for removing visible watermarks is presented. Independent component analysis (ICA) is utilized to separate source images from watermarked and reference images. Three independent component analysis approaches are examined in the proposed algorithm, which includes joint approximate diagonalization of eigenmatrices, second-order blind identification, and FastICA. Moreover, five different visible watermarking methods to embed uniform and linear-gradient watermarks are implemented. The experimental results show that visible watermarks are successfully removed, and that the proposed algorithm is independent of both the adopted ICA approach and the visible watermarking method. In the final experiment, several public domain images sourced from various websites are tested. The results of this study demonstrate that the proposed algorithm can blindly and successfully remove the visible watermarks without knowing the watermarking methods in advance

Color Images Enhancement using Weighted Histogram Separation

This paper presents a modified approach to the successive mean quantization transform, which is called as the weighted histogram separation (WHS) for enhancement of color images. Property of WHS situates between the successive mean quantization transform and the histogram equalization. In addition, this approach is further applied to the local enhancement, which is similar to the adaptive histogram equalization, and it is termed as the adaptive weighted histogram separation (AWHS). A comparison with successive mean quantization transform and histogram equalization has been performed in the experiments.

Tamper proofing and attack identification of corrupted image by using semi-fragile multiple-watermarking algorithm

We propose a novel semi-fragile multiple-watermarking algorithm based on quantization index modulation. This algorithm utilizes two quantization steps to yield the non-uniform intervals in the real-number axis. Each interval corresponds to one binary symbol, includes stable-zero (S0), unstable-zero (U0), stable-one (S1), and unstable-one (U1). In addition, visual cryptography is integrated with the watermarking algorithm to increase the watermark capacity. Therefore, the host image is embedded the multiple watermarks, and then we extract the watermarks from the corrupted image. According to the extracted watermarks, the algorithm achieves the tamper proofing and attack identification. From the experimental result, it shows single and multiple tampered areas are detected and demonstrates that the amount of test images will not influence the accuracy of attack identification.

Video enhancement based on saturation adjustment and contrast enhancement

We propose a new algorithm to improve the visual appearance of compressed videos, which are derived and reproduced from old films. The new technique is especially useful in handling the digitized old films of digital archives. Two main techniques, saturation adjustment and contrast enhancement, are implemented to improve the chrominance and luminance of video frames on HSL color space. For contrast enhancement, we use weighted histogram separation (WHS) to improve the luminance. Subsequently, the saturation ratio transfer function is proposed to adjust the saturation level of every frame. Furthermore, the new calculation method for the error of inter-frame is adopted to avoid the incorrectly enhanced result and the intensive computation consumed in motion estimation. The experimental results demonstrate that the proposed method outperforms the existing approaches in terms of video quality.

DCT-Based Image Protection using Dual-Domain Bi-Watermarking Algorithm

A dual-domain bi-watermarking algorithm is proposed in this paper. This algorithm embeds bi-watermark in DCT domain, but bi-watermark can be extracted in both spatial and DCT domains. Therefore, it can implement on the DCT-based compressed image/frame. The dual-domain bi-watermarking algorithm is the extension of the spatial-domain bi-watermarking algorithm, which implements quantization index modulation with two quantization step sizes. These quantization step sizes construct the non-uniform quantization intervals. Additionally, the luminance quantization table of JPEG compression is considered in the algorithm. In the experimental result, two extracted watermarks show the capability for various compression rates, and the watermarks also reveal the different robustness against the global and the regional attacks.

Automatic video diagnosing method using embedded crypto-watermarks

This paper proposes a novel automatic video diagnosing method. The purpose of this study is to detect the attack added on the authorized video and identify the attack category. The video is added with the crypto-watermarks using dual-domain quaternary watermarking algorithm in advance. The crypto-watermarks, which are generated using visual cryptography, have different capabilities against the various attacks. We extract the watermarks from the suspected video, measure the bit-error-rate between the extracted and specified crypto-watermarks, and then analyze bit-error-rates to determine what kind of attack added on the video. The experimental results demonstrate that the proposed method not only can identify the single attack, but it can identify the composite attack and detect the corrupted frames. Even if the video is not embedded with crypto-watermarks, we can differentiate it from the authorized videos.

Hiding multiple data in color images by histogram modification

We present a new histogram-based data-hiding algorithm that secret data is embedded in the least significant bit of the histogram value. To change the pixel value, it alters the histogram to accomplish data-hiding work. In the proposed algorithm, it is able to perform data hiding on the one-dimension histogram, two-dimension histogram map and three-dimension histogram cube. Besides, the multiple secret data hiding in various combinations of histogram spaces are successfully demonstrated in our experimental results. In addition, the natural and limited color images are tested in our experiments.

Compression and protection of JPEG images

The objective of this research is to design a new JPEG-based compression scheme which simultaneously considers the security issue. Our method starts from dividing image into non-overlapping blocks with size 8×8. Among these blocks, some are used as reference blocks and the rest are used as query blocks. A query block is the combination of the residual and the resultant of a filtered reference block. We put our emphasis on how to estimate an appropriate filter and then use it as part of a secret key. With both reference blocks and the residuals of query blocks, one is able to encode secured images using a correct secret key. The experiment results will demonstrate that how different secret keys can control the quality of restored image based on the priority of authority.

2.5-Domain Tri-Watermarking Algorithm for DCT-Based Video Protection

A 2.5-domain tri-watermarking algorithm (2.5D-TW) is presented in this paper. The proposed algorithm is the integration of dual domain bi-watermarking algorithm and visual cryptography, and the embedded tri-watermark is composed of three binary watermarks. The tri-watermark is embedded into the encoded blocks in discrete cosine transform (DCT) domain, however, the tri-watermark can be extracted from the DCT blocks and the decoded frames in spatial domain. Moreover, two types of third binary watermark of the tri-watermark are developed namely the intra-watermark and inter-watermark, those binary watermarks reveal the different robustness against various attacks. The proposed method attempts to localize the tampered areas and to detect the temporal attack.

Pattern recognition using rotation-invariant filter-driven template matching

The objective of this work is to propose a new template matching scheme which is able to deal with the recognition issue against rotation. The proposed scheme, rotation-invariant filter-driven template matching (RI-FTM), starts to transform a Cartesian-coordinate pattern to a polar-coordinate pattern. Subsequently, we put our emphasis on how to estimate an appropriate filter which is adopted to establish the connection between query pattern and reference pattern, and then the similarity between those two patterns is computed via sum of squared differences (SSD). In addition, the proposed method can shorten the width of filter to reduce the computing time. The experiment results will demonstrate our method is capable of recognitions of license plate characters and commercial logos.