Der-Chyuan Lou

A semi-blind digital watermarking scheme based on singular value decomposition

This paper presents a robust watermarking approach for hiding grayscale watermarks into digital images. Plugging the codebook concept into the singular value decomposition (SVD), the proposed method embeds the singular values (SVs) of the original image into the watermark one to attain the lossless objective. The experimental results show that the proposed scheme guarantees the extracted watermark on an average and the worst PSNR values of 24.91 and 19.96 dB, respectively. In addition to the guarantee of the quality of extracted watermark image, the security of the referenced watermark is further strengthened by applying chaos permutation on it in advance. The proposed scheme leads to satisfactory robustness to various attacks and is compared to other well-known grayscale watermarking methods to reveal its efficiency for practical applications.

A robust watermarking scheme using self-reference image

In this paper, a robust watermark scheme for copyright protection is proposed. By modifying the original image in transform domain and embedding a watermark in the difference values between the original image and its reference image, the proposed scheme overcomes the weak robustness problem of embedding a watermark in the spatial domain. Besides, the watermark extraction does not require the original image so it is more practical in real application. The experimental results show that the proposed scheme provides not only good image quality, but is also robust against various attacks, such as JPEG lossy compression, filtering and noise addition.

Fault resilient and compression tolerant digital signature for image authentication

Many watermarking schemes have been proposed to protect the authority of the image producer. These schemes can help the image producer to assert the ownership when their images are illegal reproduced. A buyer may want to make sure that the received commodity is from the legal sender and prove its integrity. In this situation, digital signature schemes can meet these requirements. In this sender-receiver protocol, images are always compressed before transmission. So compression tolerant image-features have to be designed to replace the hash functions in conventional digital signature schemes. In this paper, a public-key based fault resilient and compression tolerant digital signature is proposed. The proposed method can not only verify the authenticity and the integrity of commodities, but also can locate the illegal modifications. Furthermore, the proposed method can provide the capability of recovery if images are tampered.

A copyright protection scheme for digital images using visual cryptography technique

A robust copyright protection scheme for digital image is proposed in the paper. In the proposed scheme, the watermark does not require to be embedded into the protected image but is used to generate a secret image and a public image by using the visual cryptography technique. Then the secret image is registered to certified authority (CA) for further protection. In the step of watermark extraction, the watermark can be acquired by performing exclusive-OR (XOR) operation between the secret image and the public image. The experimental results show that the proposed scheme not only can clearly verify the copyright of the digital image, but also is robust to withstand several image processing attacks such as JPEG lossy compression, cropping, noise adding, sharpening and blurring attacks.

Multiple layer data hiding scheme for medical images

Nowadays, the transmission of digitized medical information has become very convenient due to the generality of Internet. Regardless of the prevention of medical fault, the real-time detection of abnormal event, the support of clinical decision, even the model developing of medical service based on patient, Internet has created the biggest benefit to achieve the goals of promoting patient safety and medicine quality. However, it is easier that the hackers can grab or duplicate the digitized information on the Internet. This will cause following problems of medical security and copyright protection. Therefore, the information hiding techniques are developed for protection of medical information and copyright. This paper proposes a multiple-layer data hiding technique in spatial domain. It utilizes a reduced difference expansion method to embed the bitstream in the least significant bits (LSBs) of the expanded differences. By using the reduced difference expansion method, we can embed a large amount of data in a medical image whose quality can also be maintained. Moreover, the original image can be restored after extracting the hidden data from the stego-image. Experimental results show that the proposed scheme provides higher embedding capacity at the same level image quality compared with Tians difference expansion method.

Steganographic Method for Secure Communications

Cryptographic methods secure an important message by encrypting it to an unrecognized form of data which may arouse the interest of cryptanalysis for part of the recipients. Steganographic methods hide the encrypted message in cover carriers so that it cannot be seen while it is transmitted on public communication channels such as computer network. Many steganogrphic methods embed a large amount of the secret information in the first k LSBs of the pixels of the cover images. Because of the imperfect sensibility of the human visual system, the existence of the embedded secret information can be imperceptible. Unfortunately, the hidden secret information may be discovered by the common-cover-carrier attack if it has not been appropriately disposed. In this paper, an LSB-based steganographic method is proposed to resolve this problem. By using variable-size insertion and redundant Gaussion noise adding, the stego-images created with the proposed method can survive both the human visual system and the common-cover-carrier attack. Moreover, many cryptographic protocols are involved in the proposed method to resolve the problems of security and key management that may be encountered in other steganogrpahic methods. The proposed method is hence suitable for secure communications.

A steganographic scheme for secure communications based on the chaos and euler Theorem

Steganography has been proposed as a methodology for transmitting messages through innocuous covers to conceal their existence. This work proposes an asymmetric image steganographic method based on a chaotic dynamic system and the Euler theorem. The hidden message can be recovered using orbits different from the embedding orbits, and the original image is not required to extract the hidden message. Experimental results and discussions reveal that the proposed scheme possesses security, imperceptibility and survivability.

LSB steganographic method based on reversible histogram transformation function for resisting statistical steganalysis

Statistical steganalysis schemes detect the existence of secret information embedded by steganography. The x^2-detection and Regular-Singular (RS)-attack methods are two well-known statistical steganalysis schemes used against LSB (least significant bit) steganography. The embedded message length can be estimated accurately by these two steganalysis schemes. For secret communication, the resistance of steganography against steganalysis is very important for information security. To avoid the enemys attempts, the statistical features between stego-images and cover images should be as similar as possible for better resistance to steganalysis. In this manuscript, a reversible histogram transformation function-based LSB steganographic method is proposed to resist statistical steganalysis. The experimental results show that the proposed method resists not only RS-attack but also x^2-detection methods.

Image authentication and integrity verification via content-based watermarks and a public key cryptosystem

A technique using the inherent feature map of the underlying image as the watermark is proposed in this work. First, the binary feature map is extracted as watermark and partitioned into blocks. Secondly, neighboring feature map blocks are blended and encrypted for insertion. On the receiver side, the feature map from the received image is extracted again and compared against the recovered watermark to verify the integrity and authenticity. In addition the capability of detecting geometric transformation, removal of original objects and addition of foreign objects, the proposed scheme is also capable of localizing tampering and detecting cropping without a priori knowledge about the image.

Dual-wrapped digital watermarking scheme for image copyright protection

Digital watermarking is an effective way to protect the rightful ownership of multimedia contents. In this paper, a two-phase watermarking scheme is proposed, which extracts both the grayscale watermark and the binary one from the protected images to achieve the copyright protection goal. In the first phase, the proposed method utilizes the pixel values of the original image to construct a grayscale watermark image. In the second phase, a binary watermark image can be further retrieved via the just-procured-permuted grayscale watermark from the first phase. Under these circumstances, the proposed technique results in lossless embedding; in other words, the protected images are the same as the original ones. The overall verification procedure does not need the original image. Only those who have the original grayscale watermark and the corresponding secret keys can extract the grayscale and binary watermarks sequentially, which enhances security and robustness of the proposed watermarking system. Experimental results show that the proposed approach satisfies the general requirements of image watermarking and is superior to related methods in terms of transparency and robustness. Moreover, it is easier to be implemented than transform-domain techniques. These flexible features make the proposed method more feasible and practical for copyright protection.