Showing papers on "Night vision published in 2006"

Pedestrian Detection usingInfraredimages and Histograms of Oriented Gradients

Abstract: Thispaperpresents acomplete methodforpedes- trian detection applied toinfrared images. First, westudy an imagedescriptor basedonhistograms oforiented gradients (HOG),associated witha Support Vector Machine(SVM) classifier andevaluate itsefficiency. Afterhaving tunedthe HOG descriptor andtheclassifier, weinclude this methodin acomplete system, whichdeals withstereo infrared images. Thisapproach gives goodresults forwindowclassification, andapreliminary testapplied onavideosequence proves thatthis approach isverypromising. I.INTRODUCTION Since thelast fewyears now,thedevelopment ofdriving assistance systems hasbeenveryactive inorder toin- crease thevehicle anditsenvironment safety. Atthe present time, themainobjective inthisdomainisto provide thedrivers withsomeinformation concerning its environment andanypotential hazard. Oneamongall useful information isthedetection andlocalization ofa pedestrian infront ofavehicle. Thisproblem ofdetecting pedestrians isaverydifficult problemthathasessentially beenaddressed using vision sensors, imageprocessing andpattern recognition techniques. Inparticular, detecting pedestrians thanks to images isacomplex challenge duetotheir appearance andposevariability. Inthecontext ofdaylight vision, several approaches havebeenproposed andarebased on different imageprocessing techniques ormachine learning (9), (5), (12). Recently, owingtothedevelopment oflow-cost infrared cameras, night vision systems havegained moreand moreinterest, thusincreasing theneedofautomatic detection ofpedestrians atnight. Thisproblem of detecting pedestrians frominfrared images hasbeen investigated byvarious research teamsinthelast years. Themainmethodology isbasedon extracting cues (symmetry, shape-independent

Crepuscular and Nocturnal Illumination and Its Effects on Color Perception by the Nocturnal Hawkmoth Deilephila elpenor

Abstract: Recent studies have shown that certain nocturnal insect and vertebrate species have true color vision under nocturnal illumination. Thus, their vision is potentially affected by changes in the spectral quality of twilight and nocturnal illumination, due to the presence or absence of the moon, artificial light pollution and other factors. We investigated this in the following manner. First we measured the spectral irradiance (from 300 to 700 nm) during the day, sunset, twilight, full moon, new moon, and in the presence of high levels of light pollution. The spectra were then converted to both human-based chromaticities and to relative quantum catches for the nocturnal hawkmoth Deilephila elpenor, which has color vision. The reflectance spectra of various flowers and leaves and the red hindwings of D. elpenor were also converted to chromaticities and relative quantum catches. Finally, the achromatic and chromatic contrasts (with and without von Kries color constancy) of the flowers and hindwings against a leaf background were determined under the various lighting environments. The twilight and nocturnal illuminants were substantially different from each other, resulting in significantly different contrasts. The addition of von Kries color constancy significantly reduced the effect of changing illuminants on chromatic contrast, suggesting that, even in this light-limited environment, the ability of color vision to provide reliable signals under changing illuminants may offset the concurrent threefold decrease in sensitivity and spatial resolution. Given this, color vision may be more common in crepuscular and nocturnal species than previously considered.

Nocturnal colour vision – not as rare as we might think

Abstract: The dual retina of humans and most vertebrates consists of multiple types of cone for colour vision in bright light and one single type of rod, leaving these animals colour-blind at night. Instead of comparing the signals from different spectral types of photoreceptors, they use one highly sensitive receptor, thus improving the signal-to-noise ratio. However, nocturnal moths and geckos can discriminate colours at extremely dim light intensities when humans are colour-blind, by sacrificing spatial and temporal rather than spectral resolution. The advantages of colour vision are just as obvious at night as they are during the day. Colour vision is much more reliable than achromatic contrast, not only under changing light intensities, but also under the colour changes occurring during dusk and dawn. It can be expected that nocturnal animals other than moths and geckos make use of the highly reliable colour signals in dim light.

Design of midinfrared photodetectors enhanced by surface plasmons on grating structures

Abstract: The authors propose to exploit the unique properties of surface plasmons to enhance the signal-to-noise ratio of midinfrared photodetectors. The proposed photodetector consists of a slit in a metallic slab filled with absorptive semiconductor material. Light absorption in the slit is enhanced due to Fabry-Perot resonances. Further absorption enhancement is achieved by surrounding the slit with a series of periodic grooves that enable the excitation of surface plasmons that carry electromagnetic energy towards the slit. Using this scheme, they design and optimize a photodetector operating at 0=9.8 m with a roughly 250 times enhancement in the absorption per unit of volume of semiconductor material compared to conventional photodetectors operating at the same wavelength. © 2006 American Institute of Physics. DOI: 10.1063/1.2360896 Midinfrared photodetectors and imaging systems operating in the vicinity of 10 m wavelength are important in applications ranging from night vision to astronomy research. 1 To suppress noise caused by thermal fluctuation, usually these detection systems have to be cooled, 1‐3 which greatly increases the cost and limits the portability. To improve signal/noise ratio, it is desirable to reduce the active detector volume from which the noise arises without affecting the absorbed light power. In this letter, we computationally explore the use of surface plasmons in these systems to improve the signal/noise ratio. The proposed structure, shown in Fig. 1a, consists of a metallic slit, surrounded by a linear grating structure. The entire structure is placed on top of an insulating oxide. The slit is filled with absorptive semiconductor material, and has a width that is far smaller than the operating wavelength. The metal regions serve both as electrical contacts and as a concentrator that funnels light into the deep-subwavelength slit. 4‐6 To maximize the concentration effects, we combine two distinct mechanisms that relate to the presence of the slit and the grating structure. 7 A metal slit supports a propagating TE mode, even when the width of the slit is at deepsubwavelength scales. Moreover, due to the strong impedance mismatch between the modes in the slit and free-space propagating waves, strong reflection can occur at the entrances to the slit. Consequently, with an appropriate choice of the length, the slit forms a Fabry-Perot resonator, and light absorption in the slit is resonantly enhanced. The grating, on the other hand, enhances the light absorption in the slit by converting incident electromagnetic EM waves into surface plasmons on the metal surface that can be funneled into the slit. 8 The area from which EM energy is collected can be substantially larger than the slit width and gives rise to significant enhancements in the absorbed energy. With a careful choice of the geometric parameters of the structure, these two mechanisms can be made to occur at the same wavelength, resulting in an optimized efficiency of the devices. To simulate the response of this structure for a normally incident EM plane wave, we use a two-dimensional finitedifference frequency-domain method, 9,10 which directly uses experimental data for the frequency-dependent dielectric constant of metals such as gold, 11 including both the real and imaginary parts, with no further approximation. For the detective materials in the slit, we have chosen to use HgCdTe MCT with a frequency independent dielectric permittivity of =12.5+i1.75. 2,11 The substrate is a low-index oxide

Magnetically activated switch

Abstract: An apparatus for sensing relative positions of mechanically coupled devices. The apparatus includes a magnetically actuated switch connected to a set of flux conductors to form a switch assembly. A permanent magnet is affixed to a set of flux conductors to form a magnet assembly. The flux conductors are positioned adjacently to conduct flux from the permanent magnet to the magnetically actuated switch. Movement of either assembly results in the reduction of flux conduction between the magnet and the magnetically actuated switch. The apparatus can be integrated into a helmet mount for night vision goggles to sense the relative position of the helmet mount for controlling the operation of the night vision goggle.

Bovine and porcine transscleral solute transport: influence of lipophilicity and the Choroid-Bruch's layer.

Abstract: Advances in cellular and molecular biology have shown that an elevation in vascular endothelial growth factor (VEGF) is a key contributor to vision-threatening diseases such as diabetic retinopathy and age-related macular degeneration.1 To inhibit the expression and/or activity of VEGF, several pharmacological agents2 including corticosteroids,3 nonsteroidal anti-inflammatory drugs,4 anti-VEGF antibodies, VEGF soluble receptors, and VEGF aptamers5 are being developed. It is noteworthy that a monoclonal VEGF antibody (Avastin; Genentech, South San Francisco, CA) and a VEGF aptamer (Macugen; Eye Tech, New York, NY) have been recently approved to inhibit angiogenesis associated with colorectal cancer and for the treatment of age-related macular degeneration, respectively. However, the bottleneck in the treatment of retinal angiogenic disorders as well as other diseases of the posterior segment is the delivery of adequate levels of drugs to the retina for prolonged periods. The topical ocular route is inefficient in delivering adequate drug levels to the retina, and systemic modes of administration require high doses for delivering therapeutic concentrations, leading to systemic toxicity.6 Although intravitreal administration delivers adequate drug levels to the retina, repeated intravitreal injections as well as the surgical placement of intravitreal implants are associated with complications such as retinal detachment, endophthalmitis, and cataracts.7 Thus, there is a need for the development of alternative approaches for effective retinal drug delivery. Transscleral routes are now emerging as viable alternatives for retinal drug delivery. Studies over the past four decades have shown that the sclera is more permeable than the cornea8 and that various approaches, including particulate systems,3,5 episcleral implants,9 fibrin sealants,10 and collagen matrices,11 can be used for delivering effective drug levels transsclerally in a sustained manner to the retina. Despite this promise, relatively little is known about the drug permeability properties of the sclera and the underlying layers. In the transscleral route of drug entry, drug placed next to the sclera is expected to reach the retina primarily via transport across the sclera and underlying tissues including the choroid–Bruch’s layer and RPE. In all the earlier reports on transscleral drug transport, the solute permeability across the sclera has been reported. Also, the permeability-limiting nature of the RPE is well known.12–14 It is likely that the choroid layer containing Bruch’s membrane, located between the sclera and the RPE,15 can also affect the permeability of the drugs. There are no earlier reports on the influence of this layer on transscleral drug diffusion, although it is known that Bruch’s membrane thickens and the choroidal layer thins out with aging in the human eye.16 Our previous results demonstrate that celecoxib (a selective Cox-2 inhibitor) and budesonide (a corticosteroid) can inhibit VEGF expression in cell cultures.3,4,17 We have also demonstrated that transscleral sustained retinal delivery of celecoxib inhibits VEGF expression and vascular leakage in a diabetic rat model.17 Because of the promise of budesonide and celecoxib as therapeutic agents for inhibiting VEGF expression and other inflammatory mediators in disorders of the posterior segment, we chose these lipophilic, neutral molecules for use the present study. Further, we assessed commonly used marker solutes, including mannitol (hydrophilic, neutral), sodium fluorescein (hydrophilic, anionic), and rhodamine 6G (R6G; lipophilic, cationic). For investigating the effects of the choroid–Bruch’s layer on transscleral transport, we used bovine and porcine eyes in side-by-side diffusion chambers. The bovine eyes were used because freshly excised bovine eyes are readily available, and transport studies with the bovine eyes have been reported.18 The porcine eye, although limited in supply, resembles the human eye better in anatomic characteristics.19 The bovine eye, unlike the porcine eye, has a modified choroid called the choroid-tapetum, which enables night vision. The choroid layer in this report refers to the choroid–Bruch’s membrane combination with (bovine) or without (porcine) the tapetum.

A security system for mass transit and mass transportation

Abstract: A security system and method for mass transit and mass transportation whereby high capacity mobile vehicles such as ships, buses, planes, trains and subways transporting large numbers of passengers or cargo, are continuously monitored and secured (See fig.1 ). Sensors are utilized to detect and alert the presence of radioactive or explosive materials on board as well as within close proximity of the vehicle (See Fig. 1, sensors door, and engine room). Sensors are also used to identify and track cargo and people, such as drivers, operators, employees, crew, and passengers, and provide continuous location and tracking thereof from the point of initial entry to the final point of exit (See Fig. 1, sensors in cargo hold, and sensor in engine room). Additionally, a global positioning system (GPS) provides location data, and wireless data and telecommunications link provides two-way data and voice communication with any designated remote location by using one of several modes of wireless telecommunication (See Fig. 1, telecomm antenna, cell jamming antenna). Cameras provide visual observation within designated viewable areas, and may be activated by any detection of motion, and are infrared or night vision capable allowing viewing even in extremely poor light conditions (See Fig. 1, cameras in door, bridge, engine room). DVR recording allow a huge amount of video content from the cameras to be digitally recorded, then played back later for further analysis. Finally, the Security System may optionally have an Internet Protocol (IP) address thereby allowing authorized persons to access the system from secured Internet connection.

Range gated active night vision system for automobiles

Abstract: Night vision for automobiles is an emerging safety feature that is being introduced for automotive safety. We develop what we believe is an innovative new night vision system using gated imaging principles. The concept of gated imaging is described and its basic advantages, including the backscatter reduction mechanism for improved vision through fog, rain, and snow. Evaluation of performance is presented by analyzing bar pattern modulation and comparing Johnson chart predictions.

A 3D Outdoor Scene Scanner Based on a Night-Vision Range-Gated Active Imaging System

Abstract: We present a 3D outdoor scene scanner for the acquisition of kilometers-deep scenes in night conditions. Its imaging system is based on a compact and low-cost pulsed laser illuminator and a light-intensifier equipped CCD camera. By precisely synchronizing both the illuminator and the camera shutter, it is possible to acquire "slices" of the scene at specific known distances. We show that even with large laser pulses and without megahertz-capable electronics, the third dimension can be recovered for the whole range of the scene by processing only two images acquired in specific conditions. As the pixel intensities of the images produced by active imaging systems vary with the square of the range, and due to the limited dynamics of image sensors, scanning long-range scenes with shorter "slices" allows the camera gain to be adjusted with respect to the range and the accuracy to be enhanced. The imaging system as well as the different image processing steps are detailed in this paper and an example of typical results is given.

Third-generation sensors for night vision

Abstract: Third generation sensors are under development to enhance capabilities for target detection and identification, threat warning, and 3D imaging. Distinct programs for both cooled HgCdTe and uncooled microbolometer devices are part of this thrust. This paper will describe the technology for HgCdle two-colour, high-definition imaging sensors and threat warning devices, avalanche photodiode arrays for 3D imaging, and the supporting technology being developed to enhance the readouts that support these devices. Uncooled detector initiatives will also be described to reduce pixel size in conjunction with the production of 480×640 arrays. Finally, efforts are also beginning to move both photon and thermal detectors closer to radiative-limited performance while simultaneously reducing the cooling requirements for photon detectors.

Handheld Standoff Mine Detection System (HSTAMIDS) Field Evaluation in Thailand

Abstract: The Humanitarian Demining Research and Development Program of the US Army RDECOM CERDEC Night Vision and Electronic Sensors Directorate (NVESD), under the direction of the Office of Assistant Secretary of Defense for Special Operations and Low-Intensity Conflict (OASD SO/LIC) and with participation from the International Test and Evaluation Program (ITEP) for humanitarian demining, conducted an in-country field evaluation of the Handheld Standoff Mine Detection System (HSTAMIDS) in the southern African country of Namibia. Participants included the US Humanitarian Demining Team of NVESD; ITEP personnel from several member countries; deminers from two non-governmental organizations in Angola, Menschen Gegen Minen (MgM) and HALO Trust; and CyTerra Corporation. The primary objectives were to demonstrate the performance of the U.S. Army's newest handheld multisensor mine detector, the HSTAMIDS, to the performance of the metal detector being used by local demining organizations and also to assess the performance of deminers using the HSTAMIDS after limited experience and training.

Dark adaptation of human rod bipolar cells measured from the b-wave of the scotopic electroretinogram.

Abstract: To examine the dark adaptation of human rod bipolar cells in vivo, we recorded ganzfeld ERGs to (a) a family of flashes of increasing intensity, (b) dim test flashes presented on a range of background intensities, and (c) dim test flashes presented before, and up to 40 min after, exposure to intense illumination eliciting bleaches from a few per cent to near total. The dim flash ERG was characterized by a prominent b-wave response generated principally by rod bipolar cells. In the presence of background illumination the response reached peak earlier and desensitized according to Weber's Law. Following bleaching exposures, the response was initially greatly desensitized, but thereafter recovered slowly with time. For small bleaches, the desensitization was accompanied by acceleration, in much the same way as for real light. Following a near-total bleach, the response was unrecordable for >10 min, but after ∼23 min half-maximal sensitivity was reached, and full sensitivity was restored between ∼35 and 40 min. With smaller bleaches, recovery commenced earlier. We converted the post-bleach measurements of desensitization into ‘equivalent background intensities’ using a Crawford transformation. Across the range of bleaching levels, the results were described by a prominent ‘S2’ component (0.24 decades min−1) together with a smaller and slower ‘S3’ component (0.06 decades min−1), as is found for dark adaptation of the scotopic visual system. We attribute the S2 component to the presence of unregenerated opsin, and we speculate that the S3 component results from ion channel closure by all-trans retinal.

Wavefront-guided Enhancements Using the WaveLight Excimer Laser in Symptomatic Eyes Previously Treated With LASIK

Abstract: PURPOSE: To describe our clinical experience in wavefront-guided LASIK enhancements using the WaveLight ALLEGRETTO system (WaveLight Technologie AG, Erlangen, Germany) for symptomatic eyes previously treated with standard LASIK METHODS: Twenty-six eyes of 20 patients with residual myopia, hyperopia, or mixed astigmatism and/or night vision symptoms after primary standard LASIK were considered for wavefront-guided customized retreatment using the WaveLight ALLEGRETTO WAVE 200 Hz excimer laser system (model 106) Preoperative best spectaclecorrected visual acuity (BSCVA), uncorrected visual acuity, topography with the ALLEGRETTO Topolyzer, wavefront analysis using the ALLEGRETTO WAVE Tscherning Analyzer, and contrast sensitivity were compared to postoperative (enhancement) measurements RESULTS: Twenty-two of the original 26 eyes underwent wavefront-guided enhancement, 4 were excluded because they did not meet wavefront-guided treatment inclusion guidelines of this study Mean follow-up was 8 months (range: 6 to 13 months) All patients were within 050 diopters (manifest refraction) of intended postoperative refraction The mean preoperative BSCVA improved from 20/25 to 20/18 postoperatively All patients gained at least one line of BSCVA, and a maximum of three lines There was no loss of BSCVA in any patient The total amount of high order aberrations (RMSH) decreased from an average of 104 to 046 µm Patients also had a mean improvement in low contrast sensitivity of 59% CONCLUSIONS: Based on this small series, customized wavefront-guided enhancements using the WaveLight ALLEGRETTO system in patients who underwent previous LASIK appear to be safe and effective in correcting residual refractive error, reducing high order aberrations, and improving visual symptoms when reliable and reproducible measurements are achieved [J Refract Surg 2006;22:xxx-xxx] S everal wavefront-guided excimer laser platforms are available today, and some have been shown to provide good results in enhancement in patients with residual problems after refractive surgery 1,2 This study is designed to evaluate the safety and effi cacy of wavefront-guided LASIK enhancements using the ALLEGRETTO system (Wavefront analyzer and ALLEGRETTO WAVE 200Hz excimer laser; WaveLight Technologie AG, Erlangen, Germany) for symptomatic eyes after LASIK

Visual experience and patient satisfaction with wavefront-guided laser in situ keratomileusis.

Abstract: PURPOSE: To determine the correlation between patient perception and clinical measurements after wavefront-guided laser in situ keratomileusis (LASIK). SETTING: Multicenter clinical trial. METHODS: In this retrospective analysis of clinical study results in 274 eyes, wavefront-guided LASIK procedures were performed in 274 myopic-astigmatic eyes at 6 sites. Comprehensive evaluations of vision and ocular health were conducted preoperatively and for 6 months postoperatively. Visual acuity and contrast sensitivity were measured, and questionnaires were administered. Questionnaire responses were compared with clinical measurements. RESULTS: The overall distribution shifted toward "more satisfied." The "very satisfied" population increased by as much as 70% in all areas. There was no significant change in frequency of visual symptoms. Patients were more expressive about visual decline than visual improvement. Perception of changes in vision appeared to be related to mesopic contrast sensitivity and mesopic contrast sensitivity under glare. Mesopic pupil diameter was not a major predictor of patient satisfaction. Contact lens wearers were more satisfied with postoperative vision than were spectacle wearers. Men were more likely to report visual symptoms and to complain about night vision, although their changes were the same as those of the women. Residual refractive error was a major predictor for most questionnaire items. CONCLUSION: Most patients were as satisfied or more satisfied with their postoperative uncorrected visual acuity than with their preoperative best corrected visual acuity. By continuing to minimize postoperative refractive error through the use of nomograms and improved technology, visual complaints such as night glare and halo could be diminished or even eliminated. The study shows that subjective experience affected satisfaction with results. Some dissatisfaction might be mitigated by being sure patients are educated and have realistic expectations before surgery.

Congenital stationary night blindness associated with mutations in GRM6 encoding glutamate receptor MGluR6

Abstract: Congenital stationary night blindness (CSNB) is a non-progressive retinal disorder characterised by defective night vision from birth1 that is clinically and genetically heterogeneous. It is most commonly inherited as an X linked disorder, but autosomal dominant (OMIM #163500) and recessive (OMIM#258100) forms have been described. A recent report describes mutations of the GRM6 gene in three patients with autosomal recessive CSNB.2 GRM6 encodes the glutamate receptor MGluR6, which is expressed by the rod and cone ON bipolar cells.3 Pharmacological block of this receptor in primates4,5 leads to a similar CSNB phenotype as that described in subjects with GRM6 mutations.2 We have previously identified mutations in CACNA1F and NYX genes in males with X linked CSNB,6,7 and have encountered several female patients with a similar phenotype. We screened these affected females for mutations in RHO which can cause autosomal dominant …

Pupil size and corneal laser surgery.

Abstract: Purpose of review The role of scotopic pupil size as a factor in predicting night vision complaints is controversial. This review summarizes reports in the literature, some that have found and some that have failed to find a correlation with scotopic pupil size and night vision complaints. Recent findings Pupil-measuring devices are discussed along with informed consent issues and reports showing that wavefront aberrations increase with increasing pupil size. A new objective measuring device (Larson) showed a correlation with postoperative starbursts and pupil size and a decrease in starbursts with wavefront-guided treatments compared with conventional excimer laser treatments. Cortical adaptation allows many patients to adapt to their new night vision. Treatment options for those who remain symptomatic include drops to reduce pupil size and wavefront-guided retreatments. Summary Reports in the literature are conflicting, and refractive surgeons would be wise to inform their patients that large scotopic pupil size is a potential risk factor for night vision complaints. By doing this they will follow the recommendations in recent patient information brochures of both VISX (Santa Clara, California) and Alcon (Orlando, Florida) and on the United States Food and Drug Administration web site.

Equipment and Techniques for Nocturnal Wildlife Studies

Abstract: Many biologists speculate on the nocturnal behavior of wildlife. Night-vision technologies may provide ways to move beyond speculation to observation of nocturnal activity. Nocturnal activity data collection is often secondary to broader study objectives; consequently, techniques for such studies are poorly understood and infrequently used. We reviewed 53 papers to examine image enhancement (i.e., night vision) and assess trends in nocturnal research techniques. We also conducted a field study on nocturnal behavior of roosting cranes (Grus spp.) to evaluate equipment function and efficacy for wildlife studies. A third-generation night-vision scope greatly outperformed a pair of first-generation night-vision binoculars, and we were able to identify cranes by species and observe and record their behaviors while they were on their nocturnal roost sites. Techniques reported in the literature included use of moonlight or natural ambient light, spotlight or simulated luminosity, remote photography, surveillance radar, infrared thermal imaging, and image enhancement. With the many techniques available, scientists can select the procedure or a combination of strategies explicit to their purpose. We believe night-viewing technologies are an exceptional, nonintrusive, functional tool for wildlife ecology studies. However, even the best equipment will have problems or issues with contrast, inclement weather, and large group size and density. Regardless of the specific method used and the inherent challenges, we believe third-generation, American-manufactured night-vision equipment can provide valuable insight into the complete life history of animals and can promote a more comprehensive approach to wildlife studies.

Back-up electric power generator for electronic components attached to automatic firearms

Abstract: A firearm improvement taking the form of a mechanical dynamo installed in an automatic firearm. Several components either replace certain parts of the firearm or are added to the firearm. In conjunction with the operation of the firearm, the components generate electric energy which is then stored in a capacitor, battery, or other element for the storage of electric energy, or supply power to a battery recharging unit attached to the firearm. The electric energy contained in the storage component, or used to recharge the batteries placed in the recharging unit, may be used at a later time as a back-up power supply for electronic components attached to or incorporated into the firearm, such as red-dot or reflex sights, laser sighting equipment, or night vision equipment.

Clip-on infrared imager

Abstract: A clip-on infrared imager may be coupled and decoupled to an existing night vision system to add infrared imaging to provide a fused image through at least one of the night vision system eyepieces.

Topography-guided CATz versus conventional LASIK for myopia with the NIDEK EC-5000: A bilateral eye study.

Abstract: PURPOSE To evaluate the difference in visual acuity, subjective night vision glare, and higher order aberrations in eyes with myopia with or without astigmatism operated with topography-guided customized corneal LASIK and conventional LASIK. METHODS This contralateral study includes 46 eyes (23 patients) that underwent topography-guided corneal customized LASIK using the customized aspheric treatment zone (CATz) ablation profile in one eye and conventional LASIK using the NIDEK EC-5000 Advanced Vision Excimer laser system (NAVEX) in the other eye for myopia with or without astigmatism. Patients were masked to which eye underwent topography-guided CATz or conventional LASIK. Postoperative glare and root-mean-square (RMS) values for total higher order aberrations were measured at 1 and 3 months and compared between the two eyes. RESULTS No significant difference was noted in uncorrected visual acuity between the two groups at 1 and 3 months postoperatively. Of all patients, 81% stated glare was higher in conventionally treated eyes than in the CATz-treated eyes at 1 and 3 months postoperatively. The RMS values for total coma (0.2385 vs 0.1522) and spherical aberration (0.2381 vs 0.1058) in conventionally treated and CATz-treated eyes were significantly higher in conventionally treated eyes (P=.029 and P=.004, respectively) at 3-month follow-up. CONCLUSIONS Topography-guided corneal customized LASIK with the CATz profile gave better night vision quality as compared to conventional LASIK with expanded treatment zone. Better night vision quality was associated with less induced spherical aberrations and coma postoperatively in the CATz treatment group.

Concealed weapon identification using terahertz imaging sensors

Abstract: Terahertz imaging sensors are being considered for providing a concealed weapon identification capability for military and security applications. In this paper the difficulty of this task is assessed in a systematic way. Using imaging systems operating at 640 GHz, high resolution imagery of possible concealed weapons has been collected. Information in this imagery is removed in a controlled and systematic way and then used in a human observer perception experiment. From the perception data, a calibration factor describing the overall difficulty of this task was derived. This calibration factor is used with a general model of human observer performance developed at the US Army Night Vision and Electronic Sensors Directorate to predict the task performance of observers using terahertz imaging sensors. Example performance calculations for a representative imaging sensor are shown.

Multitask vision architecture for refractive vision corrections

Abstract: A multitask vision architecture is constructed based on multitask vision-metrics derived from wave aberration of the eye. The multitask vision metrics include at least one of the followings: vision clarity of eye that measures optical quality of an eye against those in a cohort of eyes with normal acuity, aberration-induced vision symptoms, retinal image quality for best vision and night vision, and retinal image quality for a range of focus depth. The multitask vision architectures is applied for determining a wavefront shape for an optimized vision correction, for specifying excessive aberrations in an eye, and for specifying quality of a vision product.

Standard target sets for field sensor performance measurements

Abstract: The US Army Night Vision and Electronic Sensors Directorate (NVESD) Modeling and Simulation Division develops sensors models (FLIR 92, NV Therm, NV Therm IP) that predict the comparative performance of electro-optical sensors. The NVESD modeling branch developed a 12-vehicle, 12-aspect target signature set in 1998 with a known cycle criteria. It will be referred to as the 12-target set. This 12-target set has and will continue to be the modeling "gold standard" for laboratory human perception experiments supporting sensor performance modeling, and has been employed in dozens of published experiments. The 12-target set is, however, too costly for most acquisition field tests and evaluations. The authors developed an 8-vehicle 3-aspect target set, referred to as the 8- target set, and measured its discrimination task difficulty, (N50 and V50). Target identification (ID) range performance predictions for several sensors were made based on those V50/N50 values. A field collection of the 8-target set using those sensors provided imagery for a human perception study. The human perception study found excellent agreement between predicted and measured range performance. The goal of this development is to create a "silver standard" target set that is as dependable in measuring sensor performance as the "gold standard", and is affordable for Milestone A and other field trials.

Motor vehicle comprising a lighting device with a variable illumination beam

Abstract: The vehicle has a control device (7) to control the vehicle's headlamps (3), which illuminates a front end of a motor vehicle. A position determination unit (6) determines the relative position of a road user in the surroundings of the motor vehicle. An illumination volume or illumination characteristics of the headlamps are controlled based on the determined position of the road user. The illumination unit includes an image recording unit such as a CCD, CMOS, infrared or night vision camera, which records an image of the front end of the vehicle.

Probability of identification of small hand-held objects for electro-optic forward-looking infrared systems

Abstract: This paper describes research on the measurement of the 50% probability of identification cycle criteria (N50,V50) for a set of hand-held objects normally held or used in a single hand. These cycle criteria are used to calibrate the Night Vision Electronic Sensors Directorate (NVESD) target acquisition models. The target set consists of 12 objects, from innocuous to potentially lethal. Objects are imaged in the visible, midwave infrared (MWIR), and long-wave infrared (LWIR) spectrum at 12 different aspects. Two human perception experiments are performed. The first experiment simulates an incremental constriction of the imaging systems modulation transfer function (MTF). The N50, and V50 calibration criteria are measured from this perception experiment. The second experiment not only simulates an incremental constriction of the system MTF but also down samples the imagery to simulate the objects at various ranges. The N50 and V50 values are used in NVTherm 2002 and NVThermIP, respectively, to generate range prediction curves for both the LWIR and MWIR sensors. The range predictions from both NVTherm versions are then compared with the observer results from the second perception experiment. The comparison between the results of the second experiment and the model predictions provides a verification of measured cycle criteria.

A Region-Based Image Fusion Method Using the Expectation-Maximization Algorithm

Abstract: We present a novel region-based image fusion method using a rigorous application of estimation theory. This method takes advantage of the similar intensity or texture in a region for fusion. A statistical image formation model using Gaussian mixture distortion is built for each region and the EM (expectation-maximization) algorithm is used in conjunction with the model to develop the region-level EM fusion algorithm to produce the fused image. Since in most applications of image fusion, objects carry the information of interest and regions can be used to represent objects, the region-based fusion approaches could be more meaningful than pixel-based methods. Our experiments demonstrate the efficiency of the proposed region-base fusion method and the advantages in dealing with region interface artifacts for concealed weapon detection and night vision applications.