Redundancy of stereoscopic images: Experimental Evaluation

With the recent advancement in visualization devices over the last years, we are seeing a growing market for stereoscopic content. In order to convey 3D content by means of stereoscopic displays, one needs to transmit and display at least 2 points of view of the video content. This has profound implications on the resources required to transmit the content, as well as demands on the complexity of the visualization system. It is known that stereoscopic images are redundant, which may prove useful for compression and may have positive effect on the construction of the visualization device. In this paper we describe an experimental evaluation of data redundancy in color stereoscopic images. In the experiments with computer generated and real life and test stereo images, several observers visually tested the stereopsis threshold and accuracy of parallax measuring in anaglyphs and stereograms as functions of the blur degree of one of two stereo images and color saturation threshold in one of two stereo images for which full color 3D perception with no visible color degradations is maintained. The experiments support a theoretical estimate that one has to add, to data required to reproduce one of two stereoscopic images, only several percents of that amount of data in order to achieve stereoscopic perception

Super-resolution in turbulent videos: making profit from damage

It is shown that one can make use of local instabilities in turbulent video frames to enhance image resolution beyond the limit defined by the image sampling rate. The paper outlines the processing algorithm, presents its experimental verification on simulated and real-life videos and discusses its potentials and limitations.Comment: 11 pages, 2 figures. Submitted to Optics Letters, 10-07-0

Arp2/3 Branched Actin Network Mediates Filopodia-Like Bundles Formation In Vitro

During cellular migration, regulated actin assembly takes place at the cell leading edge, with continuous disassembly deeper in the cell interior. Actin polymerization at the plasma membrane results in the extension of cellular protrusions in the form of lamellipodia and filopodia. To understand how cells regulate the transformation of lamellipodia into filopodia, and to determine the major factors that control their transition, we studied actin self-assembly in the presence of Arp2/3 complex, WASp-VCA and fascin, the major proteins participating in the assembly of lamellipodia and filopodia. We show that in the early stages of actin polymerization fascin is passive while Arp2/3 mediates the formation of dense and highly branched aster-like networks of actin. Once filaments in the periphery of an aster get long enough, fascin becomes active, linking the filaments into bundles which emanate radially from the aster's surface, resulting in the formation of star-like structures. We show that the number of bundles nucleated per star, as well as their thickness and length, is controlled by the initial concentration of Arp2/3 complex ([Arp2/3]). Specifically, we tested several values of [Arp2/3] and found that for given initial concentrations of actin and fascin, the number of bundles per star, as well as their length and thickness are larger when [Arp2/3] is lower. Our experimental findings can be interpreted and explained using a theoretical scheme which combines Kinetic Monte Carlo simulations for aster growth, with a simple mechanistic model for bundles' formation and growth. According to this model, bundles emerge from the aster's (sparsely branched) surface layer. Bundles begin to form when the bending energy associated with bringing two filaments into contact is compensated by the energetic gain resulting from their fascin linking energy. As time evolves the initially thin and short bundles elongate, thus reducing their bending energy and allowing them to further associate and create thicker bundles, until all actin monomers are consumed. This process is essentially irreversible on the time scale of actin polymerization. Two structural parameters, L, which is proportional to the length of filament tips at the aster periphery and b, the spacing between their origins, dictate the onset of bundling; both depending on [Arp2/3]. Cells may use a similar mechanism to regulate filopodia formation along the cell leading edge. Such a mechanism may allow cells to have control over the localization of filopodia by recruiting specific proteins that regulate filaments length (e.g., Dia2) to specific sites along lamellipodia

Real Time Turbulent Video Perfecting by Image Stabilization and Super-Resolution

Image and video quality in Long Range Observation Systems (LOROS) suffer from atmospheric turbulence that causes small neighbourhoods in image frames to chaotically move in different directions and substantially hampers visual analysis of such image and video sequences. The paper presents a real-time algorithm for perfecting turbulence degraded videos by means of stabilization and resolution enhancement. The latter is achieved by exploiting the turbulent motion. The algorithm involves generation of a reference frame and estimation, for each incoming video frame, of a local image displacement map with respect to the reference frame; segmentation of the displacement map into two classes: stationary and moving objects and resolution enhancement of stationary objects, while preserving real motion. Experiments with synthetic and real-life sequences have shown that the enhanced videos, generated in real time, exhibit substantially better resolution and complete stabilization for stationary objects while retaining real motion.Comment: Submitted to The Seventh IASTED International Conference on Visualization, Imaging, and Image Processing (VIIP 2007) August, 2007 Palma de Mallorca, Spai

Using cross-talk simulation to predict the performance of anaglyph 3-D glasses

The anaglyph 3-D method is a widely used technique for presenting stereoscopic 3-D images. Its primary advantage is that it will work on any full-color display (LCDs, plasmas, and even prints) and only requires that the user view the anaglyph image using a pair of anaglyph 3-D glasses with usually one lens tinted red and the other lens tinted cyan (blue plus green). A common image-quality problem of anaglyph 3-D images is high levels of cross-talk — the incomplete isolation of the left and right image channels such that each eye sees a “ghost” of the opposite perspective view. An anaglyph cross-talk simulation model has been developed which allows the amount of anaglyph cross-talk to be estimated based on the spectral characteristics of the anaglyph glasses and the display. The model is validated using a visual cross-talk ranking test which indicates good agreement. The model is then used to consider two scenarios for the reduction of cross-talk in anaglyph systems and finds that a considerable reduction is likely to be achieved by using spectrally pure displays. The study also finds that the 3-D performance of commercial anaglyph glasses can be significantly better than handmade anaglyph glasses

Effect of sex pheromone emission on the attraction of Lobesia botrana

Since the discovery of Lobesia botrana Denis & Schiffermüller (Lepidoptera: Tortricidae) sex pheromone, it has played an important role in the control and detection of this pest, for example, through the use of pheromone-baited traps and mating disruption techniques. Rubber septa are the most common pheromone dispensers used in monitoring traps, but often dispenser performance is not optimized. The key to improve methods based on pheromones as attractants (monitoring, mass trapping, or ‘attract and kill’) is to know the optimum emission interval, because release rates can strongly affect the attraction. In this work, five levels of pheromone load with different release rates were compared in traps using mesoporous pheromone dispensers to investigate the optimum release rate maximizing L. botrana catches. Residual pheromone loads of the dispensers were extracted and quantified by gas chromatography, to study release profiles and to estimate the various emission levels. The efficacy of pheromone emission was measured in field trials as number of moths caught. A quadratic model was fitted to relate the numbers caught vs. the daily emission rates. The resulting quadratic term was statistically significant, confirming the existence of a relative maximum for L. botrana catches. Taking into account that the trial was carried out only in one location, an optimum emission value of ca. 400 μg per day could be considered to enhance the attraction of L. botrana under West-Mediterranean weather conditions.© 2011 The Authors. Entomologia Experimentalis et Applicata © 2011 The Netherlands Entomological Society.Vacas González, S.; Alfaro Cañamás, C.; Zarzo Castelló, M.; Navarro-Llopis, V.; Primo Millo, J. (2011). Effect of sex pheromone emission on the attraction of Lobesia botrana. Entomologia Experimentalis et Applicata. 139(3):250-257. doi:10.1111/j.1570-7458.2011.01124.xS2502571393Anshelevich, L., Kehat, M., Dunkelblum, E., & Greenberg, S. (1994). 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Complete Genome Sequence and Comparative Analysis of the Wild-type Commensal Escherichia coli Strain SE11 Isolated from a Healthy Adult

We sequenced and analyzed the genome of a commensal Escherichia coli (E. coli) strain SE11 (O152:H28) recently isolated from feces of a healthy adult and classified into E. coli phylogenetic group B1. SE11 harbored a 4.8 Mb chromosome encoding 4679 protein-coding genes and six plasmids encoding 323 protein-coding genes. None of the SE11 genes had sequence similarity to known genes encoding phage- and plasmid-borne virulence factors found in pathogenic E. coli strains. The comparative genome analysis with the laboratory strain K-12 MG1655 identified 62 poorly conserved genes between these two non-pathogenic strains and 1186 genes absent in MG1655. These genes in SE11 were mostly encoded in large insertion regions on the chromosome or in the plasmids, and were notably abundant in genes of fimbriae and autotransporters, which are cell surface appendages that largely contribute to the adherence ability of bacteria to host cells and bacterial conjugation. These data suggest that SE11 may have evolved to acquire and accumulate the functions advantageous for stable colonization of intestinal cells, and that the adhesion-associated functions are important for the commensality of E. coli in human gut habitat

Methods for reducing visual discomfort in stereoscopic 3D: A review

This work was supported by the EPSRC Grant EP/M01469X/1, “Geometric Evaluation of Stereoscopic Video”