Light Bars Research Articles

El Wenufoye, and: Negro Matapacos

El Wenufoye*, and: Negro Matapacos David Brunson (bio) el wenufoye* Tear gas swells through the plaza. We coverour faces with sweaters as a blue, green, and red flag flails wildly in the smoke. A bottle shattersinto flame against an armored vehicle. In the palace across the avenue, gunshotsfrom ’73 still sound, Allende’s blood still staining the wooden floor. We run across a Santiagotwice destroyed—September 11, 1541, the Mapuche reclaiming their stolen land;September 11, 1973, the U.S. coup— back into Casa Violetta as the military policefire rubber bullets into the mass of Mapuche children and grandparents. When does historycollapse into tragedy? Three thousand dead in our towers? Four thousand dead or missing?A musician’s hands broken? A poet poisoned? Forty thousand years of culture destroyed?We flee, but a gas-masked woman stands in the plaza, and though surrounded by watercannons, she watches as her flag burns. [End Page 19] negro matapacos Author’s Note: In 2011, a street dog became famous in Santiago by joining student protestors, who named him Negro Matapacos. During protests in 2019, the image of the dog, wearing a red handkerchief around his neck, was used on posters and murals as a symbol of resistance. A black room.A thin bar oflight. A blackriver—blackoil, a rainbowrefracted overa black surface.Black soot inblack nostrils,a black bullet ina black chamber,black eyes, gas.Here, a body’sblack gold—a mountain’sshadow: blackwires, a carbattery, a blacklatex glove,black waterspilled, a screamsilenced in ablack night.A burned body—the black fingersgrasp a blackbed frame.A black dogpainted acrossa black street— [End Page 20] David Brunson David Brunson is an MFA candidate in poetry and a translator studying at the University of Arkansas. He serves as outreach director, assistant translation editor, and assistant poetry editor at The Arkansas International. Footnotes * flag of the Mapuche people Copyright © 2019 University of Hawai‘i Press

Supplemental Light-emitting Diode Effects on the Growth, Fruit Quality, and Yield of Two Greenhouse-grown Strawberry (Fragaria ×ananassa) Cultivars

Recent interest in off-season greenhouse-grown food crops, in combination with supplemental (top) lighting (SL), has created opportunities for local production of high-value fruit crops such as strawberries (Fragaria ×ananassa). Light-emitting diodes (LEDs) as SL can be tailored to a specific quality of radiation (i.e., wavelengths) to promote increased production and quality of greenhouse-grown crops. The objectives of this study were to evaluate the effects of three LED light bars on off-season controlled environmental agriculture (CEA) production of 2-day neutral strawberry cultivars: Albion and San Andreas. LED effects on overall vegetative biomass (e.g., stolon production, crown number, and leaf area), marketable fruit yield, and fruit quality [e.g., individual fruit weight and soluble solids content (SSC)] were measured during decreasing daylengths from Oct. to Dec. 2017 (Expt. 1) and increasing daylengths of Jan. to Apr. 2018 (Expt. 2). We hypothesized that the addition of SL via three LED treatments would increase measured parameters. Specifically, it was expected that the LED bars [high blue (HB) and low blue (LB)] with greater intensities of blue and red light would produce greater yields and also increase SSC of the berries. The hypotheses were tested by evaluating three LED light top bars [white far-red (WFR; 440–450 nm), HB, and LB], with wavelength peaks of blue (450 nm) and red (665 nm) light, but differing photosynthetic photon flux densities (PPFDs). Results from these experiments showed that individual strawberry fruit size and SSC were increased with the use of HB and LB LEDs during the shortening days of Expt. 1. Increased leaf area and crown number were also affected positively within all LED treatments (WFR, LB, HB) for ‘San Andreas’. Relative to Expt. 1, the lengthening days of Expt. 2 elicited more limited fruit responses, although increased stolon production within all treatments was reported. In addition, differences between cultivars in leaf area and SSC were observed with ‘San Andreas’ growing larger leaves and ‘Albion’ berries having a greater SSC. Individual fruit weight of both cultivars responded similarly, with increased fruit size in LB and HB, specifically within both Expt. 1 and Expt. 2. Our studies indicate that the addition of SL, in the form of LB and HB improved overall strawberry fruit quality and plant growth during shortening daylengths and under greenhouse CEA conditions.

Rotation and Translation Invariant Palmprint Recognition With Biologically Inspired Transform

Extracting rotation and translation invariant features is a difficult task for palmprint recognition. Traditional methods have difficulty in dealing with palmprint images degraded by those variations. Studies have shown that neurons at higher levels exhibit an increasing degree of invariance to above mentioned image variations. Moreover, primary visual cortex(V1) is believed to give stronger responses to light bars of certain directions. Based on these observations, a biologically inspired transform feature extractor, namely BIT, for palmprint recognition is proposed in this paper. BIT involves two stages, which mimics visual information processing in V1. In the first stage, we build an orientation edge detector to highlight the edges response in each direction. The orientation edge detector is primarily composed of a phase congruency based edge detector and a bipolar filter. After that, a local spatial frequency detector produces a response, converting rotation factors of orientation edges into a horizontal shifted map. In the second stage, the orientation edge detector and local spatial frequency detector are applied again, which converts shifted map into an invariant pixel in feature map. Extensive experimental results not only show that our method is robust to image variations including rotation and translation, but also illustrate the effectiveness and discriminability of the extracted invariant palmprint features in recognition problems.

Directional backlight module based on pixelated nano-gratings

A directional backlight is of great interest in the field of glasses-free 3D display, privacy display, and energy efficient display. In this paper, a directional backlight module including a LED light bar, a collimating lens, a diffuser, and a waveguide is proposed. The waveguide is covered by nanogratings with a density gradience to optimize the illumination uniformity and to preserve the angular divergence of the emitted light. The proposed directional backlight achieved a divergence angle of ±6.17° and a uniformity of 88%. The directional backlight based on pixelated nanogratings features good uniformity, thin form factor, low cost, and large tolerance of the fabrication process, thus can be used in the illumination of glass-free 3D display, privacy display, and energy efficient display.

35.1: Invited Paper: Measurement and Standardization of Display Lighting Units

Display lighting unit has always been the focus for optimization when comes into display engineering to improve its electrical, optical, and electro‐optical performance. In recent years, with the development of reflective LCD (liquid crystal display), electronic paper display, laser projection display, etc., the measurement of display lighting unit has received more attention. The IEC TC110 "Electronic Display" established the standardization team PT62595 to develop international standards. Currently, the project team has worked a variety of lighting technologies, including back light unit (BLU) and front light unit (FLU), light module and engine, light bar, and light components. In this paper, we reviewed the roadmap of this group and key items that involve in the measurement methods to give an overview of the documents.In the previous year, the IEC released two new standards, IEC62595‐2‐2 “Measuring methods of LED light bars used in LCD BLUs” and IEC62595‐2‐3 “Electro‐optical measuring methods of LED frontlight unit”. Both documents have now been put into the implementation in the display industry.In IEC 6595‐2‐2, spatial luminance uniformity and angular luminance, color uniformity and color angular uniformity were addressed. In Figure 1, it shows an example of a typical light bar luminance distribution profile to indicate the luminance uniformity by quantifying the information along axis.Example of the luminance distribution profiles along the x‐axis, Lv(x, o)figureIn addition, in order to achieve these characteristics, the optical coupling analysis and optimization between the light bar and the light guide plate (LGP) was discussed. Furthermore, this work introduced the specifications on the requirements for test environment, the architecture of the test equipment, the reference diffuser settings, and the coordinate system.In IEC 62595‐2‐3, the standard specifies the measurement conditions and measuring methods for determining electrical, optical, and electro‐optical properties of LED FLUs for reflective displays. In FLU, the light ray of the FLU with a reflective LC display can be sensitive to the testing position and viewing direction. As shown in Figure 2, light rays are introduced to the LGP (light guide plate) from the coupling side. The rays are reflected on the inner surfaces of the micro‐structures (on the front surface) due to TIR (total internal reflection). The FLU is served as a transparent medium that has reflection property on both surfaces. We explained some of the factors that were covered in the standard document for the measurement and evaluation of both surfaces, including angular luminance distribution, luminance uniformity, spectral power distribution, chromaticity uniformity and angular color uniformity in CIE 1976 system, as well as FLU‐polarization characteristics and optical noise (undesired luminance) along the zenith angle in any azimuth angle.Light rays of FLU with a reflective LC displayfigure

At least two distinct mechanisms control binocular luster, rivalry, and perceived rotation with contrast and average luminance disparities.

When one views a square-wave grating and dichoptically changes the average luminance or contrast of the monocular images, at least three perceptual phenomena might occur. These are the Venetian blind effect, or a perceived rotation of the bars around individual vertical axes; binocular luster, or a perceived shimmering; and binocular rivalry, or an alternating perception between the views of the two eyes. Perception of luster and rivalry occur when the "light bars" in the grating dichoptically straddle the background luminance (one eye’s image has a higher luminance than the background and the other eye’s image has a lower luminance than the background), with little impact from the "dark bars." Perception of rotation, on the other hand, is related to average luminance or contrast disparity, independent of whether or not the "light bars" straddle the background luminance. The patterns for perceived rotation versus binocular luster and binocular rivalry suggest at least two separate mechanisms in the visual system for processing luminance and contrast information over and above their differing physiological states suggested by their different appearances. While luster and rivalry depend directly on the relation between stimuli and the background, perceived rotation depends on the magnitude of the luminance or contrast disparity, as described by the generalized difference model.

Color-switchable liquid crystal smart window with multi-layered light guiding structures.

We propose here a novel multi-layered waveguide liquid crystal (LC) smart window with full color rendering based on a polymer-network liquid crystal system. The inserted position of three-primary-color LED light bars is specially designed, which is parallel to the LC alignment to obtain a higher difference between transparent and scattering states. The optimal matching of polymer-network LC system is experimentally achieved by comparing several groups of LC and reactive mesogen materials. The prepared smart window is measured and analyzed in detail including optical/chromatic test, morphology characterization, and actual application effect. The proposed architecture opens up new prospects of flexible color switchable ability and synchronized full-color display for smart windows without limitations of slow LC response time and complicated field sequential driving scheme.

Driver Behavior in Response to Flashing Lights

Flashing yellow warning lights notify drivers about the presence of work along the road. Current standards for these lights address performance of the individual light but not how lights should function when multiple lights are used. In the present study, warning lights were used to delineate a lane change taper in a simulated work zone. Lights flashed with varying intensities and either randomly or in sequence, with lights flashing in turn along the length of the lane change taper, either to the right or to the left. In half of the trials, a flashing police light bar was used on a vehicle located within the simulated work zone. Participants were asked to drive a vehicle approaching the work zone and to identify, as quickly as possible, in which direction the taper’s lane change was (either to the right or left). Drivers were able to correctly identify the taper from farther away when the lights flashed in a sequential pattern than when the flash pattern was random; and the presence of a police light bar resulted in shorter identification distances. The results, along with previous research, can inform standards for the use of flashing lights and police lights in work zones for the safety of drivers and workers.

Experimental investigation on thermal performances of SMD LEDs light bar: Junction-to-case thermal resistance and junction temperature estimation

In this present work, the heat sink thermal resistance, junction-to-case thermal resistance and junction temperature of SMD LEDs light bar module are determined using luminous flux measurements and photo-electro-thermal (PET) theory equations, proposed as original investigation. The obtained results showed that junction temperature increases with the electrical input power supply, which affects the luminous flux efficacy of investigated SMD LEDs light bar. Thus, we noticed the luminous efficacy fall, which it passes from 27.18 lm/W at 0.25 W to 7.51 lm/W at 2 W, while the total luminous flux increases until reach a maximum value of about 15.26 lm at 1.5 W which the spectral radiant flux of LEDs light bar remains higher. The junction-to-case thermal resistance Rjc increases with the input power until reaches a value of about 60 °C/W for 1 W, after Rjc decreases for higher input power (i.e. 2 W). Thus, the junction temperature Tj for SMD LEDs light bar is estimated for different injected powers Pd; Tj passes from 31.33 °C to 98.11 °C at Tamb of 23 °C, as Pd increases from 0.25 W to 2 W. In addition, these first results remain a starting point to study an advanced lighting system based on this type of LEDs in our future works.

Investigation of Guidewire Deformation in Blood Vessels Based on an SQP Algorithm

This paper proposes a solution to the simulated deformation of guidewires when they come in contact with the blood vessel in an interventional surgery simulation training system. Starting from the principle of minimum energy, the guidewire is evenly dispersed into a rigid light bar articulation model. A sequential quadratic programming (SQP) algorithm is used to nonlinearly optimize the deflection angle of each light bar. When the elastic potential energy of the guidewire reaches a minimum, we can get the guidewire deformation we want to solve. The method proposed in this paper avoids necessity of delving into contact deformation caused by the contact force between the guidewire and the blood vessel wall, while solving the problem of the deformation of the guidewire due to the pose of the contact points. We use an ABAQUS (finite element software) simulation to verify that this solution has a theoretical simulation accuracy of 5.11%, and the designed experiments prove that the actual simulation accuracy is about 11%. Moreover, we also simulated the bending stress state of the guidewire by using the deflection angle of each bar. In addition, in order to achieve the most suitable simulation results, we discuss the discrete density of the guidewire model from the perspective of algorithm time consumption and simulation accuracy.

A new species of Ancistrus Kner, 1854 (Siluriformes: Loricariidae) from rio Madeira basin, Amazonas State, Brazil

ABSTRACT During the Mosaico do Apuí expedition in 2006, a new species of Ancistrus was found in the rio Sucunduri, a large tributary of the rio Madeira basin in south Amazonas State. The new species has a unique color pattern for the genus and is distinguished by the presence of alternate light and dark vertical bars on the trunk. Other Ancistrini genera have species with a similar color pattern, but the new species is clearly distinguished by a lack of plates on the snout and presence of fleshy tentacles on the snout as in all Ancistrus representatives. We also provide comments on the taxonomic status of the A. bolivianus, A. heterorhynchus and A. marcapatae.

Light bar center extraction algorithm for automotive weld sealant strips

汽车焊缝涂胶能够提高车身密封水平, 需要对胶条进行检测并且获得三维信息。激光三角法是应用广泛的检测方法, 其关键技术之一是准确提取光条中心。但针对黑色被检胶体, 光条中心提取鲁棒性差, 因此提出了一种基于光条分割的Hessian矩阵定位和高斯曲线拟合的算法。首先, 将整体图像对比度提高, 运用去噪算法消除干扰的噪声; 然后用极值法初步定位光条, 结合Hessian矩阵对激光条的中心进行定位; 最后利用高斯曲线准确拟合出激光条的中心。实验研究表明, 在对光条图像添加噪声幅度为100的白噪声之后进行处理, 同样能够将精度控制在亚像素级别, 能够提高黑色被检测物体的光条的稳定性。

A Needs Assessment of People with Hearing Impairment for Hearing Augmentation Technology Development: Focusing on Risk Context Awareness Communication

본 연구의 목적은 청각장애인이 경험하는 위험상황과 청각 대체기술로 사용하는 보조기기 사용실태를 조사하여 청각증강 기술 개발의 적용점을 모색하는 데 있다. 이를 위해 청각장애 등급을 판정받은 청각장애인을 대상으로 설문조사하여 총 355명의 자료를 분석에 사용하였다. 연구결과 첫째, 소리 및 진동을 인지한 경험이 없는 상황으로 교통수단, 사물, 자연 영역 순으로 높게 나타났다. 이 중 교통수단의 소리와 진동을 인지하지 못한 비율이 높아 일상생활에서 청각장애인이 경험하는 위험 가능성이 높은 것으로 조사되었다. 둘째, 청각장애인이 경험한 위험상황은 교통사고, 보행사고, 가정에서의 일상생활 순으로 높게 조사되었다. 셋째, 위험상황 인식과 알림을 위한 보조기기로 2G폰/스마트폰, 진동디지털알람시계, 경광등, 진동손목시계의 인지도가 높았으며, 2G폰/스마트폰의 만족도가 가장 높았다. 넷째, 의사소통을 위한 보조기기로 보청기, 스마트폰, 영상전화기, 인공와우, 2G폰 순으로 인지도가 높았으며, 스마트폰을 사용하였을 경우 만족도와 의사소통 개선정도가 가장 높게 조사되었다. 마지막으로 청각증강 기술 개발을 위해 고려할 점으로 휴대/착용 편의성, 가격, 동작 정확도 순으로 선호하였으며, 알림 전달 방식은 시각(문자와 빛)을 활용한 알림방식을 선호하였다. 연구결과에 근거하여 위험상황에서 청각장애인의 청각증강 기술 개발을 위한 정책적, 실천적 방안을 제시하였다.The purpose of this study is to find the application point of hearing augmentation technology development through examining the risk context experience of people with hearing impairment and the use of assistive device used as an alternative technology. Data of 355 people with hearing impairment with official disability grading was analyzed. The results of this study are first, research participants had no experience of recognizing any sound or vibration in situations highest in the order of means of transportation, material, and nature. Especially the ratio of being unable to recognize the sound and vibration of means of transportation was high, which implies the high possibility of people with hearing impairment experiencing risk. Secondly, the risk context that people with hearing impairment will most likely to experience are highest in the order of traffic accident, pedestrian accident, and daily life at home. Thirdly, the recognition of 2G phone/smart phone, vibrating digital alarm clock, light bar, vibrating wrist watch as assistive device for risk context awareness and notification was high and the satisfaction level of 2G phone/smart phone was the highest. Fourthly, the research participants had high recognition of assistive device for communication in the order of hearing aid, smart phone, videophone, cochlear implant and 2G phone and it was found that the satisfaction level and communication improvement level was the highest using the smart phone. Lastly, for the development of hearing augmentation technology the research participants recognized the importance of portable/wear convenience, price, and motion accuracy and for notification delivery means they preferred the method of using sight(text and light). Based on the results of this study policy and practical plans for hearing augmentation technology development for people with hearing impairment in risk context are proposed.

Design of a Secondary Freeform Lens of UV LED Mosquito-Trapping Lamp for Enhancing Trapping Efficiency

In this study, our proposed ultraviolet light-emitting diode (UV LED) mosquito-trapping lamp is designed to control diseases brought by insects such as mosquitoes. In order to enable the device to efficiently catch mosquitoes in a wider area, a secondary freeform lens (SFL) is designed for UV LED. The lens is mounted on a 3 W UV LED light bar as a mosquito-trapping lamp of the new UV LED light bar module to achieve axially symmetric light intensity distribution. The special SFL is used to enhance the trapping capabilities of the mosquito-trapping lamp. The results show that when the secondary freeform surface lens is applied to the experimental outdoor UV LED mosquito-trapping lamp, the trapping range can be expanded to 100π·m2 and the captured mosquitoes increased by about 300%.

Motion changes response balance between ON and OFF visual pathways

Humans are faster at detecting dark than light stationary stimuli, a temporal difference that originates early in the visual pathway. Here we show that this difference reverses when stimuli move, making detection faster for moving lights than darks. Human subjects judged the direction of moving edges and bars, and made faster and more accurate responses for light than for dark stimuli. This light/dark asymmetry is greatest at low speeds and disappears at high speeds. In parallel experiments, we recorded responses in the cat visual cortex for moving bars and again find that responses are faster for light bars than for dark bars moving at low speeds. We show that differences in the luminance-response function between ON and OFF pathways can reproduce these findings, and may explain why ON pathways are used for slow-motion image stabilization in many species.

Functional triplet motifs underlie accurate predictions of single-trial responses in populations of tuned and untuned V1 neurons

Visual stimuli evoke activity in visual cortical neuronal populations. Neuronal activity can be selectively modulated by particular visual stimulus parameters, such as the direction of a moving bar of light, resulting in well-defined trial averaged tuning properties. However, given any single stimulus parameter, a large number of neurons in visual cortex remain unmodulated, and the role of this untuned population is not well understood. Here, we use two-photon calcium imaging to record, in an unbiased manner, from large populations of layer 2/3 excitatory neurons in mouse primary visual cortex to describe co-varying activity on single trials in neuronal populations consisting of both tuned and untuned neurons. Specifically, we summarize pairwise covariability with an asymmetric partial correlation coefficient, allowing us to analyze the resultant population correlation structure, or functional network, with graph theory. Using the graph neighbors of a neuron, we find that the local population, including both tuned and untuned neurons, are able to predict individual neuron activity on a moment to moment basis, while also recapitulating tuning properties of tuned neurons. Variance explained in total population activity scales with the number of neurons imaged, demonstrating larger sample sizes are required to fully capture local network interactions. We also find that a specific functional triplet motif in the graph results in the best predictions, suggesting a signature of informative correlations in these populations. In summary, we show that unbiased sampling of the local population can explain single trial response variability as well as trial-averaged tuning properties in V1, and the ability to predict responses is tied to the occurrence of a functional triplet motif.

Rail Profile Measurement Based on Line-structured Light Vision

High-speed railway in China has undergone rapid development in recent years. Technology for structure measurement is recognized as an important aspect of steel rail quality inspection. The shape of the rail welding base is mainly gauged using mechanical contact measurement technology. Matching this technology with the escalating demands for quality inspection of steel rails is a challenging task. In this paper, a structured light measurement approach is proposed and employed which intersects the rail through the structural light plane projected by inner and outer laser sensors. These sensors form a laser light stripe curve containing the profile information of the rail surface. By processing laser light bars using image analysis and contour reduction techniques, 3-D profiles of the rails are generated. The laser plane is fitted using the coordinate points of the laser light bars converted between the image and world coordinate systems. A new calibration method based on the parallel moving target for line-structured light is proposed to improve the calibration and address the issue caused by the limited number of the extracted calibration points during free target calibration. The rail profile, including the geometric dimension, straightness, and twist of the rail, are then measured. By comparing the measured profile with the standard contour of the rails, the rail wear can then be quantitatively assessed. The experimental results show that the proposed measurement system outperforms the traditional single index detection.

Dynamic detection method of medium-low speed maglev F-track seams based on machine vision

This paper presents a dynamic detection method of medium and low speed maglev F-track seam based on machine vision detection technology. A Kalman filter light bar center extraction algorithm based on ridge line prediction is proposed for the bar image of F-track seam detection. And a threshold segmentation feature point extraction method is proposed for the center of the light bar. The static and dynamic precision of detection system are verified by the stability test, static and dynamic precision test. The static detection accuracy of end of F-track seam is less than 0.5mm and dynamic detection accuracy is less than 0.8mm. Then the static precision is less than 0.2mm the dynamic accuracy is less than 0.5mm about the horizontal F-track seam. And the static precision is less than 0.2mm, and the dynamic accuracy is less than 0.5mm about the vertical F-track seam. The detection accuracy of the system meets the requirements of F-track seam precision.

Effectiveness of Polymer Composite-Induced Passive Radiation Cooling in Thermal Management of LED Emitters and Modules: Impact on Hotspot Elimination

Effectiveness of polymer composite-induced passive radiation cooling in thermal management of LED emitters and modules is elucidated by numerical simulations coupled with key experimental observations. Specifically, various polymer-filler composites coated on the board of LED emitters and modules are investigated for their effectiveness in reducing the board as well as junction temperature. It is demonstrated that a maximum temperature drop of 11 °C can be achieved for the single chip-on-board LED emitter with 10-W input power. Moreover, for the linear LED module, a reduction of 14.53 °C is observed in the peak junction temperature of LED emitters with 1-W input power in the light bar. The polymer composite coating is also demonstrated to significantly boost the uniformity of temperature distribution and to reduce the risk of hotspot. Some of the key simulation results are further examined to be consistent with analytical modeling. Significant implications of the present polymer composite-induced passive radiation cooling results to the challenging thermal design of electronic devices with limited space are also discussed.

Contrast Sensitivity and Lateral Inhibition Are Enhanced With Macular Carotenoid Supplementation.

Once deposited in the retina, the so-called macular carotenoids lutein (L), zeaxanthin (Z), and mesozeaxanthin (MZ) have been shown to enhance visual performance. The purpose of our study was to investigate whether increasing macular pigment optical density (MPOD) could enhance lateral inhibitory processes, and thereby improve contrast sensitivity (CS). A total of 59 young (18-25 years), healthy individuals participated in this 1-year, double-masked, placebo-controlled study. MPOD was assessed via heterochromatic flicker photometry. Lateral inhibition sensitivity (LIS) was determined with a computer-based, user-adjustable Hermann grid. CS (at 8 cycles/degree) was determined with a two-alternative, forced-choice procedure. Subjects received either the placebo (n = 10), 12 mg total macular carotenoids (n = 24), or 24 mg total macular carotenoids (n = 25). MPOD, LIS, and CS increased significantly in treatment groups between baseline and 6 months, and between 6 and 12 months (P < 0.05 for all) versus placebo. The relationships between changes in MPOD and both LIS and CS were significant at 6 and 12 months (P < 0.05 for both). Changes in CS and LIS over the 12-month study period were found to be significantly related (r = 0.41; P = 0.0014). Increases in MPOD led to enhanced lateral inhibitory processes, which correspond to improved CS. Because optical filtering has the same net effect on dark versus light bars, it cannot explain these improvements. Improvement in CS with increases in MPOD therefore appears to involve enhancement of the fundamental physiological systems that give rise to edge detection.