Hao Luo

Self Embedding Watermarking Scheme Using Halftone Image

Self embedding watermarking is a technique used for tamper detection, localization and recovery. This letter proposes a novel self embedding scheme, in which the halftone version of the host image is exploited as a watermark, instead of a JPEG-compressed version used in most existing methods. Our scheme employs a pixel-wise permuted and embedded mechanism and thus overcomes some common drawbacks of the previous methods. Experimental results demonstrate our technique is effective and practical.

Hiding Multiple Watermarks in Transparencies of Visual Cryptography

This paper proposes a scheme to hide multiple watermarks in transparencies of visual cryptography. On one hand, the main properties of the traditional visual cryptography are still maintained. On the other hand, not only the encrypted image can be visible when stacking the transparencies, but also two extra watermarks can be extracted with simple computations. The scheme can be applied to hide some affiliated information of the secret image. Experimental results demonstrate the scheme is effective and practical.

Reversible watermarking for error diffused halftone images using statistical features

This paper proposes a reversible watermarking scheme for error diffused halftone images. It exploits statistical features of 2×2 binary patterns in halftone images to embed data. According to a small look-up table constructed in advance, a state sequence is extracted and losslessly compressed, and the saved space is filled up with the watermark and some side information. We modulate the extracted state sequence into a new concatenated sequence by similar pair toggling, and meanwhile the watermark and the LUT are embedded. The proposed scheme can provide a considerable capacity and the original image can be recovered if its watermarked version is intact.

A Reversible Data Hiding Scheme for 3D Point Cloud Model

This paper proposes a reversible data hiding scheme for 3D point cloud model. The method exploits the high correlation among neighboring vertices to embed data. It starts with creating a set of 8-neighbor vertices clusters with randomly selected seed vertices. Then an 8-point integer DCT is performed on these clusters and an efficient highest frequency coefficient modification technique in the integer DCT domain is employed to modulate the watermark bit. After that, the modified coefficients are inverse transformed into coordinates in the spatial domain. In data extraction, we need to recreate the modified clusters first, and other operations are the inverse process of the data hiding. The original model can be perfectly recovered using the clusters information if it is intact. This technique is suitable for some specific applications where content accuracy of the original model must be guaranteed. Moreover, the method can be easily extended to 3D point cloud model authentication

Watermarking-Based Transparency Authentication in Visual Cryptography

This paper proposes two transparency authentication schemes used in visual cryptography, which are based on watermarking techniques. In the first scheme, a secret image can be perceptible when stacking two transparencies. In addition, another watermark image is visible when shifting one transparency to an appropriate position and stacking it with the other transparency. In the second scheme, both the secret image and the watermark are of the same size, while in the first scheme, the watermark is half of the size of the secret image. No computer aid is needed in decryption in the first scheme while simple computation is required in the second one. The secret image and the watermark are encrypted at the same time in the two schemes. Experimental results demonstrate the two schemes are effective and practical.

Reversible Data Hiding for 3D Point Cloud Model

This paper proposes a reversible data hiding scheme for 3D point cloud model. It exploits the high correlation among neighbor vertices to embed data. It starts with creating a set of 8-neighbor vertices clusters with randomly selected seed vertices. Then an 8-point integer DCT is performed on these clusters and an efficient highest frequency coefficient modification technique is employed to modulate the watermark bit. In data extraction, the modified clusters are retrieved first, and other operations are the inverse process of the data hiding. The original model can be perfectly recovered if it is intact. Our scheme is suitable for some specific applications where content accuracy of the original model must be guaranteed. Moreover, the method can be used for 3D point cloud model authentication, e.g., hiding a hash sequence.

Multiple Watermarking in Visual Cryptography

This paper proposes a scheme to hide two watermarks in visual secret sharing of a gray level image. One watermark is embedded during secret image halftoning, and the other is hidden during the halftone image encryption. A non-expansion visual secret sharing model is used to encrypt the halftone image. In watermark extraction, only Exclusive-OR operation is needed, and basic properties of conventional visual cryptography technique are still preserved. Experimental results show the effectiveness of our schemes.

Halftone Image Watermarking Based on the Binary Pseudo-Wavelet Transform

With halftone images widely used in books, magazines, printer outputs, and fax documents, it is desirable to embed data in halftone images for copyright protection, content authentication and tamper detection. This paper proposes a novel watermarking method for error diffused halftone images based on the binary pseudo-wavelet transform. We employ the binary pseudo-wavelet coefficients distribution properties to embed data by modifying some highest frequency coefficients. Then the modified coefficients are inverse transformed into the spatial domain and meanwhile the watermarked image is obtained. Watermark extraction is the inverse process of watermark embedding. Experimental results show that this method is robust to attacks such as human marking and cropping, furthermore it achieves a good tradeoff between the high data capacity and the slight visual distortion.

Joint Multiple Watermarking and Non-Expansion Visual Cryptography

This paper proposes a scheme to hide two watermarks in visual secret sharing of a gray level image. One watermark is embedded during secret image halftoning, and the other watermark is hidden during the halftone image encryption. A non-expansion visual secret sharing model is used to encrypt the halftone image. In data extraction, only exclusive-OR operation is needed. Experimental results show the effectiveness of our scheme.

Joint Halftoning and Visible Watermarking

Visible watermarking is a technique to embed a perceivable image in a host image for copyright protection. Existing visible watermarking methods mainly concern about continuous-tone images, however, few attention is paid to two-tone images. This paper proposes a visible watermarking scheme for halftone images called joint halftoning and visible watermarking (JHVW). JHVW embeds data during halftoning, namely the host image is a continuous-tone image and the watermarked image is a halftone image. The watermarked halftone image contains recognizable but unobtrusive watermark information, and the details of the host image still be maintained. Our schemes can be used in applications such as in advertisement or as a restriction.