Simple Signal Extension Method for Discrete Wavelet Transform

Discrete wavelet transform of finite-length signals must necessarily handle the signal boundaries. The state-of-the-art approaches treat such boundaries in a complicated and inflexible way, using special prolog or epilog phases. This holds true in particular for images decomposed into a number of scales, exemplary in JPEG 2000 coding system. In this paper, the state-of-the-art approaches are extended to perform the treatment using a compact streaming core, possibly in multi-scale fashion. We present the core focused on CDF 5/3 wavelet and the symmetric border extension method, both employed in the JPEG 2000. As a result of our work, every input sample is visited only once, while the results are produced immediately, i.e. without buffering.Comment: preprint; presented on ICSIP 201

The Parallel Algorithm for the 2-D Discrete Wavelet Transform

The discrete wavelet transform can be found at the heart of many image-processing algorithms. Until now, the transform on general-purpose processors (CPUs) was mostly computed using a separable lifting scheme. As the lifting scheme consists of a small number of operations, it is preferred for processing using single-core CPUs. However, considering a parallel processing using multi-core processors, this scheme is inappropriate due to a large number of steps. On such architectures, the number of steps corresponds to the number of points that represent the exchange of data. Consequently, these points often form a performance bottleneck. Our approach appropriately rearranges calculations inside the transform, and thereby reduces the number of steps. In other words, we propose a new scheme that is friendly to parallel environments. When evaluating on multi-core CPUs, we consistently overcome the original lifting scheme. The evaluation was performed on 61-core Intel Xeon Phi and 8-core Intel Xeon processors.Comment: accepted for publication at ICGIP 201

Clinical Outcomes of 0.018-Inch and 0.022-Inch Bracket Slot Using the ABO Objective Grading System

Objective: To determine if there is a significant difference in the clinical outcomes of cases treated with 0.018-inch brackets vs 0.022-inch brackets according to the American Board of Orthodontics (ABO) Objective Grading System (OGS). Materials and Methods: Treatment time and the ABO-OGS standards in alignment/rotations, marginal ridges, buccolingual inclination, overjet, occlusal relationships, occlusal contacts, interproximal contacts, and root angulations were used to compare clinical outcomes between a series of 828 consecutively completed orthodontic cases (2005–2008) treated in a university graduate orthodontic clinic with 0.018-inch- and 0.022-inch-slot brackets. Results: A two-sample t-test showed a significantly shorter treatment time and lower ABO-OGS score in four categories (alignment/rotations, marginal ridges, overjet, and root angulations), as well as lower total ABO-OGS total score, with the 0.018-inch brackets. The ANCOVA—adjusting for covariants of discrepancy index, age, gender, and treatment time—showed that the 0.018-inch brackets scored significantly lower than the 0.022-inch brackets in both the alignment/rotations category and total ABO-OGS score. Conclusions: There were statistically, but not clinically, significant differences in treatment times and in total ABO-OGS scores in favor of 0.018-inch brackets as compared with the 0.022-inch brackets in a university graduate orthodontic clinic (2005–2008)

UV Dichroism in Vertically Aligned Nematic Displays

Vertically aligned negative nematics are employed in high-end projection applications, where extremely high light fluxes are employed. Under these conditions, the UV photochemical stability of the material becomes an issue that must be included in the characterization process of such devices. Photochemical aging tests for vertically aligned microdisplay, however, must take into account the linear dichroism shown by the liquid crystal material upon switching. In this work a method to evaluate UV linear dichroism is described. The method is included in a comparative study of the electrooptical performance of two negative nematic mixtures, one experimental and one commercial