1883250
Accelerated, high-quality refraction computations for volume graphics
We present an efficient framework for the high-quality rendering of discretely sampled surface-based objects with refractive effects. This requires an accurate estimation of the refraction coefficients, paired with efficient and accurate surface detection, space traversal, and backdrop image sampling. Our framework achieves these goals, by employing a high-quality spline-based filter in conjunction with a novel filtered octree space decomposition with pre-classified cells that is carefully matched to the filter and voxel neighborhood characteristics. Here, we benefit greatly from the non-negativity of the B-spline kernel. Finally, we describe an innovative scheme that achieves the high quality of pixel super-sampling on a flat backdrop plane without the overhead of tracing the actual rays across the refractive object.
18989576
Fast marching method to correct for refraction in ultrasound computed tomography
A significant obstacle in the advancement of ultrasound computed tomography has been the lack of efficient and precise methods for the tracing of the bent rays that result from the interaction of sound with refractive media. In this paper, we propose the use of the fast marching method (FMM) to solve the eikonal equation which governs the propagation of sound waves. The FMM enables us to determine with great accuracy and ease the distorted paths that the sound rays take from an emitter to the receivers. We show that knowledge of the accurate path proves crucial for an object reconstruction at high fidelity and accurate geometry. We employ a two-phase approach with an iterative method, SART, to faithfully reconstruct two tissue properties relevant in clinical diagnosis, such as mammography: speed of sound and sound attenuation. We demonstrate our results by ways of a newly designed analytical ultrasound breast phantom
218270
Cryptanalysis of a multistage encryption system
This paper analyzes the security of a new multistage encryption system (MES) recently proposed in ISCAS'2004. It is found that MES is insecure against a differential chosen-plaintext/ciphertext attack. Experiments are given to support the proposed attack. It is also pointed out that the security of MES against brute-force attacks is not sufficiently high.
16791890
JComp: A Reuse-Driven Componentization Framework for Java Applications
Program componentization has been proved to be an effective way to increase the speed and cost-effectiveness of reusing, maintaining, and understanding existing software systems. JComp is a componentization framework that supports semi-automatically extracting reusable components from an existing Java system and automatically transforming the existing system into a component-based system. Based on the automated class dominance analysis and domain knowledge, JComp introduces a novel technique to incrementally identify reusable components in a low cost but high precision way. Also, JComp provides a methodology to automate the transformation of existing object-oriented systems into component-based systems
14078750
A Novel Hierarchical Approach to Image Retrieval Using Color and Spatial Information
A novel hierarchical approach to image retrieval is proposed. First, a color label histogram is used to effectively filter out the images that are not similar to the query image in color. The proposed color label histogram built by categorizing the pixel colors is computationally much more efficient compared to other approaches. Next, the class parameters of those images passing the first filter are used to identify the images similar to the query image in spatial layout. These class parameters are obtained automatically from the proposed unsupervised segmentation algorithm. Moreover, the wavelet decomposition coefficients are used to generate the initial partition for the segmentation algorithm. It doubles the segmentation performance. At the last stage, all images passing two filters are ranked based on the total normalized distance in color and spatial layout. The experiments show the effectiveness and efficiency of our approach.
18473631
Cryptanalysis of a Chaotic Neural Network Based Multimedia Encryption Scheme
Recently, Yen and Guo proposed a chaotic neural network (CNN) for signal encryption, which was suggested as a solution for protection of digital images and videos. The present paper evaluates the security of this CNN-based encryption scheme, and points out that it is not secure from the cryptographical point of view: 1) it can be easily broken by known/chosen-plaintext attacks; 2) its security against the brute-force attack was much over-estimated. Some experiments are shown to support the results given in this paper. It is also discussed how to improve the encryption scheme.
39573562
Binary Trees and Uniform Distribution of Traffic Cutback
Abstract This article introduces the notion of the External Left Length (ELL) of binary trees, which is analogous to the notion of the External Path Length (EPL), and derives theorems about the ELL which correspond to well-known facts about the EPL. Results are applied to the analysis of the optimization of an algorithm for the smooth traffic cutback in data communication.