In this paper, we propose a novel data hiding algorithm for high dynamic range (HDR) images encoded by the OpenEXR file format. The proposed algorithm exploits each of three 10-bit mantissa fields as an embedding unit in order to conceal k bits of a secret message using an optimal base which produces the least pixel variation. An aggressive bit encoding and decomposition scheme is recommended, which offers a high probability to convey (k + 1) bits without increasing the pixel variation caused by message concealment. In addition, we present a bit inversion embedding strategy to further increase the capacities when the probability of appearance of secret bit “1” is greater than 0.5. Furthermore, we introduce an adaptive data hiding approach for concealing more secret messages in pixels with low luminance, exploiting the features of the human visual system to achieve luminance-aware adaptive data hiding. The stego HDR images produced by our algorithm coincide with the HDR image file format, causing no suspicion from malicious eavesdroppers. The generated stego HDR images and their tone-mapped low dynamic range (LDR) images reveal no perceptual differences when subjected to quantitative testing by visual difference predictor. Our algorithm can resist steganalytic attacks from the HDR and LDR RS and SPAM steganalyzers. We present the first data hiding algorithm for OpenEXR HDR images offering a high embedding rate and producing high visual quality of the stego images. Our algorithm outperforms the current state-of-the-art works.

Color transfer algorithms alter the color appearance in the source image by borrowing colors from the target image. In this paper, we present a simple yet effective generalized color transfer algorithm, taking into consideration the influences contributed from both the source and target images. We introduce the Gaussian membership function as our first color similarity measurement. This function aims at balancing the degree of similarity of color distributions between source and resultant images and that between target and resultant images, respectively. With regard to the second color similarity measurement, we combine color histogram with the statistic concept of the correlation. Referring to different weights, the histogram correlation method derives correlations at each color channel between source and resultant images and those between target and resultant images. Color transfer is optimized by automatically stabilizing correlations before producing the final color transfer resultant image. Experimental results demonstrate that our proposed algorithm automatically takes into consideration the source and target images producing a visually plausible result. The statics comparison shows that our scheme outperforms current state-of-the-art methods.

In the era of information explosion, the traditional approach to storing data have faced challenges due to the rapid growth of information. It becomes an important issue when we come to processing the large dataset and trying to retrieve the useful information from a big database. This paper presents an effective scheme which employs hybrid cache architecture on the existing database system to enhance the query performance without increasing the hardware cost. Our scheme can be applied to satisfy the traditional database query over the Internet. The experimental results collected from a practical application show that the data query can be speeded up to 26 times. Performance evaluation shows that the response time of queries is less than 0.02 seconds when the query hits the shared memory cache. The proposed architecture can be easily applied to the traditional SQL database to accelerate the database query without significant programing efforts.

Linear interpolation is a simple yet effective technique for image composition which works wells for low dynamic range (LDR) images with a fixed range of pixel values. However, it cannot provide good performance for high dynamic range (HDR) images because a high luminance image usually dominates the composition result. This paper proposes a novel algorithm for HDR composition using the linear interpolation. Our scheme decomposes HDR images to be composed into three layers where a linear interpolation can be applied on each layer individually that has been normalized. The algorithm contains three steps including the image decomposition, the image feature composition, and finally the HDR map estimation and image re-rendering. Experimental results show that the proposed approach can produce informative HDR composition images balancing the influence caused by the low or high luminance and preserving the contrast, colors, and salience. The comparison demonstrates that our scheme outperforms the current state-of-the-art methods.

We propose a novel approach for steganography using a reversible texture synthesis. A texture synthesis process resamples a smaller texture image, which synthesizes a new texture image with a similar local appearance and an arbitrary size. We weave the texture synthesis process into steganography to conceal secret messages. In contrast to using an existing cover image to hide messages, our algorithm conceals the source texture image and embeds secret messages through the process of texture synthesis. This allows us to extract the secret messages and source texture from a stego synthetic texture. Our approach offers three distinct advantages. First, our scheme offers the embedding capacity that is proportional to the size of the stego texture image. Second, a steganalytic algorithm is not likely to defeat our steganographic approach. Third, the reversible capability inherited from our scheme provides functionality, which allows recovery of the source texture. Experimental results have verified that our proposed algorithm can provide various numbers of embedding capacities, produce a visually plausible texture images, and recover the source texture.

Random unique number generator can be used for generating a series of unpredictable and unrepeatable numbers within limited ranges of data and numbers. These numbers are usually distributed equally, random, independent, unpredictable and unrepeatable. A good random number generator has to be effective for a long period and has good statistical distribution and efficient generating performance. This study proposes a computational methodology to generate pseudo-random numbers based on random base polynomial, which uses less memory but generates a great deal of unrepeated pseudo-random numbers. Then this method adopts the multi-thread parallelization to effectively get the benefits of multi-core processors to accelerate the generation of a huge amount of pseudo-random numbers.

Secure multicast provides efficient delivery which includes an identical data from a source to multiple receivers. A common solution is to apply a symmetric key that is used to encrypt the transmitted data. However, the heavy cost of the rekeying process is the main problem in large and dynamic multicast groups. The tree-based architecture is widely used to reduce the rekeying cost in terms of storage, transmission and computation. However, it usually requires extra overhead to keep key tree balance which is in order to achieve logarithmic rekeying cost. In this paper, we shall propose a new RSA-like multicast key management scheme to solve the rekeying problem. Our protocol applies a star-based architecture to eliminate the rekeying processes and provide the good performance when the membership changes in a multicast group. Furthermore, we also provide an extended multicast scheme, in which we combine public-key and symmetric-key cryptosystems to enhance the performance of multicast encryption.

We present an effective message embedding scheme for 3D models. We propose the unit length as the quantizer to generate an embedding order list and an embedding index list. Our scheme considers every two elements in the embedding order list as the order pair, and we embed 3 bits of 0 or 1 secret message into the index pair associated with the order pair. The message embedding is effective requiring, at most, adding 1 to, or subtracting 1 from, the index pair. This reflects a slight perturbation of a points coordinates where the magnitude of the perturbation is no greater than one unit length. Our algorithm achieves a high embedding capacity, being 4.5 times the number of points in the point cloud models. This amount of capacity allows us to convey a 502x502 resolution of the black-and-white image into a point cloud model consisting of 56,194 points for covert communication. The capacity magnitude is 50%-75% higher than that of the current state-ofthe- art algorithms, yet the model distortion due to the message embedding is smaller than that of our counterparts. Our algorithm is robust against translation, rotation, and uniformly scaling operations. It is fast, simple to implement, and the message can be extracted without referring to the original point cloud model. We believe our scheme is appropriate for most point cloud models.

Bogomjakov proposed a universal algorithm for permutation steganography. In this paper, we introduce a more effective algorithm. A theoretical analysis indicates that our algorithm achieves 99% of optimal when using 128 elements, while Bogomjakov 's method attains only 98.34% of optimal even when employing as many as 1,048,576 elements. We conducted an experiment using a 3-D polygon dataset for comparison. The analysis and practical experiments demonstrate that our algorithm attains a capacity closer to the optimal but has the same runtime complexity as Bogomjakov's algorithm.

This paper proposes an image-based painterly rendering algorithm for automatically synthesizing an image with color ink diffusion. We suggest a mathematical model with a physical base to simulate the phenomenon of color colloidal ink diffusing into absorbent paper. Our algorithm contains three main parts: a feature extraction phase, a Kubelka-Munk (KM) color mixing phase, and a color ink diffusion synthesis phase. In the feature extraction phase, the information of the reference image is simplified by luminance division and color segmentation. In the color mixing phase, the KM theory is employed to approximate the result when one pigment is painted upon another pigment layer. Then, in the color ink diffusion synthesis phase, the physically-based model that we propose is employed to simulate the result of color ink diffusion in absorbent paper using a texture synthesis technique. Our image-based ink diffusing rendering (IBCIDR) algorithm eliminates the drawback of conventional Chinese ink simulations, which are limited to the black ink domain, and our approach demonstrates that, without using any strokes, a color image can be automatically converted to the diffused ink style with a visually pleasing appearance.

We present an efficient digital steganographic technique for three-dimensional (3D) triangle meshes. It is based on a substitutive blind procedure in the spatial domain. The basic idea is to consider every vertex of a triangle as a message vertex. We propose an efficient data structure and advanced jump strategy to fast assign order to the message vertex. We also provide a Multi-Level Embed Procedure (MLEP), including sliding, extending, and rotating levels, to embed information based on shifting the message vertex by its geometrical property. Experimental results show that the proposed technique is efficient and secure, has high capacity and low distortion, and is robust against affine transformations (which include translation, rotation, scaling, or their combined operations). The technique provides an automatic, reversible method and has proven to be feasible in steganography.