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Vector quantisation (VQ) shows a good performance for image coding with high-compression ratios. However, there are many difficulties for image coding with VQ, especially the edge degradation and high-computational complexity. To resolve these two problems, the authors propose a new coding method based on edge orientation patterns (EOPs) by classifying image blocks into nine classes according to their...
In this paper, we propose a new reversible data hiding scheme for images compressed by Block Truncation Coding (BTC). The original image is divided into n × n sized non-overlapping blocks and encoded by BTC to obtain the BTC-compressed bitstream. Each block is presented by a low mean value, a high mean value and a binary bitmap. The proposed scheme exploits the correlation among adjacent blocks and...
This paper presents a new approach for hiding information in digital audio based on the audio-to-image wavelet transform (A2IWT) and vector quantization (VQ). In our scheme, the cover audio signal is first transformed into an image by utilizing the wavelet transform and re-sampling the coefficients, then the secret data are embedded in the obtained image using a VQ-based image steganographic scheme,...
This paper proposes a novel kind of graph-based features for image retrieval. For each color image, we divide it into R, G, B component images. For each component image, we view the 256 gray-levels as nodes and construct the Gray-level Co-occurrence Graph (GCG) by counting the number of occurrences for each possible gray-level pair as neighbors in the image. Based on the generated three directed weighted...
A novel MDC framework based on the spatial frequency quantization (SFQ) is proposed in this article. Different from other algorithms, this new three channel framework formed by using the orientation information optimization method based on the SFQ algorithm. According to the three different orientations, i.e., vertical, horizontal and diagonal directions, we use the gross and fine optimization method...
This paper proposes a method to encrypt an image in two shares with following properties. (1) The method is suitable for binary, gray level or color image encryption. (2) The bit error rates are adjustable, and thus the secret image can be recovered to different extents including lossless and nearly lossless. (3) Sizes of the share images are flexible to be changed, and thus the method can be used...
Image hashing function maps an image into a bit string which can be used to authenticate the originality of the image. In this paper, we propose a perceptual image hashing scheme that is secure and robust to visually insignificant changes but fragile enough to detect and precisely locate malicious attacks. The proposed image hashing method is based on the outlines of one-dimensional signals re-arranged...
This paper proposes a visual secret sharing scheme for color image encryption with robust and progressive decryption abilities. Robust decryption means the secret content can be still decrypted from shares even the shares are corrupted with intentional or unintentional alterations. In progressive decryption, three levels quality of secret images can be decrypted with the same shares. A lower visual...
In this paper, a novel robust audio watermarking algorithm is presented. It takes full advantage of the multi-resolution and the energy compression properties of the discrete wavelet transform (DWT) and discrete cosine transform (DCT) respectively, and embeds a pseudorandom permuted binary image in the original audio signal by vector quantization (VQ). The original audio is first transformed using...
Robust watermarking schemes often rely on hiding watermarks into carefully selected host components capable to survive a variety of attacks, or capability of detector to successfully decode watermark even with fewer components. However for a variety of permanent media damages both the credibility of such elements or detector's performance can be compromised. Through spatial domain extension of visual...
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...
This paper presents a digital watermarking scheme based on the discrete cosine transform (DCT) and singular value decomposition (SVD). In the proposed method, selected mid-band DCT coefficients from 8x8 block DCT are selected to form blocks which are later decomposed into three matrices, i.e. U, S and V. Finally the original watermark is also partitioned into blocks and then embedded into the matrix...
The transmission and storage of large amounts of vertex geometry data are required for rendering geometrically detailed 3D models. To alleviate bandwidth requirements, vector quantization (VQ) is an effective lossy vertex data compression technique for triangular meshes. With VQ methods based on stationary codebooks, we need codebooks of different levels to achieve the desired compression rate. However,...
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...
An efficient nearest neighbor codeword search algorithm for vector quantization based on the Hadamard transform is presented in this paper. Four elimination criteria are derived from two important inequalities based on three characteristic values in the Hadamard transform domain. Before the encoding process, the Hadamard transform is performed on all the codewords in the codebook and then the transformed...
A novel robust digital image watermarking algorithm based on predictive vector quantization is proposed in this paper. The robust watermark is embedded in the image by selecting the prediction mode of each PVQ coded vector according to the watermark bit. The proposed watermarking algorithm is proved to be robust against both friendly and hostile attacks, such as JPEG compression, VQ compression and...
The paper presents a novel, efficient, nearest-neighbor codeword search algorithm based on three elimination criteria in the Hadamard transform (HT) domain. Before the search process, all codewords in the codebook are Hadamard-transformed and sorted in the ascending order of their first elements. During the search process, we first perform the HT on the input vector and calculate its variance and...
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