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Contour interaction under photopic and scotopic conditions
摘要： In the present study, we asked whether contour interaction undergoes significant changes for different luminance levels in the central and peripheral visual field. This study included nine normal observers at two laboratories (five at Palacky University Olomouc, Czech Republic and four at the University of Houston, USA). Observers viewed a randomly selected Sloan letter surrounded by four equally spaced bars for several separations measured edge-to-edge in min arc. Stimuli were viewed foveally under photopic and mesopic luminances and between 5° and 12° peripherally for four different background luminances of the display monitors, corresponding to photopic, mesopic, scotopic, and dim scotopic levels. The extent of the contour interaction in the fovea is approximately 20 times smaller than in the periphery. Whereas the magnitude of foveal contour interaction markedly decreases with decreasing luminance, no consistent luminance-induced change occurs in peripheral contour interaction. The extent of contour interaction does not scale with the size of the target letter, either in the fovea or peripherally. The results support a neural origin of contour interaction consistent with the properties of center-surround antagonism.
关键词： contour interaction,photopic,crowding effect,mesopic,scotopic,luminance,peripheral vision
更新于2025-09-23 15:22:29
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Characterization of Rod Function Phenotypes Across a Range of Age-Related Macular Degeneration Severities and Subretinal Drusenoid Deposits
摘要： PURPOSE. To examine spatial changes in rod-mediated function in relationship to local structural changes across the central retina in eyes with a spectrum of age-related macular degeneration (AMD) disease severity. METHODS. Participants were categorized into five AMD severity groups based on fundus features. Scotopic thresholds were measured at 14 loci spanning 6° to 18° along the vertical meridian from one eye of each of 42 participants (mean = 71.7 ± 9.9 years). Following a 30% bleach, dark adaptation was measured at eight loci (4° to 12°). Rod intercept time (RIT) was defined from the time to detect a ?3.1 log cd/m2 stimulus. RITslope was defined from the linear fit of RIT with decreasing retinal eccentricity. The presence of subretinal drusenoid deposits (SDD), ellipsoid (EZ) band disruption, and drusen at the test loci was evaluated using optical coherence tomography. RESULTS. Scotopic thresholds indicated greater rod function loss in the macula, which correlated with increasing AMD group severity. RITslope, which captures the spatial change in the rate of dark adaptation, increased with AMD severity (P < 0.0001). Three rod function phenotypes emerged: RF1, normal rod function; RF2, normal scotopic thresholds but slowed dark adaptation; and RF3, elevated scotopic thresholds with slowed dark adaptation. Dark adaptation was slowed at all loci with SDD or EZ band disruption, and at 32% of loci with no local structural changes. CONCLUSIONS. Three rod function phenotypes were defined from combined measurement of scotopic threshold and dark adaptation. Spatial changes in dark adaptation across the macula were captured with RITslope, which may be a useful outcome measure for functional studies of AMD.
关键词： age-related macular degeneration,RIT,SDD,scotopic thresholds,dark adaptation,rod intercept time,subretinal drusenoid deposits,AMD
更新于2025-09-23 15:22:29
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Efficiency in Street Lighting Projects by Employing LED Luminaires and Mesopic Photometry
摘要： This paper discusses the importance of adapting conventional photometric quantities when lighting systems with low luminance levels are under analysis, as public lighting or external lighting in general. In this sense, it is presented an alternative methodology for lighting projects in street lighting, considering the mesopic photometry. The CIE recommendation 191:2010 proposes correction factors that convert conventional photometric quantities (photopic) into quantities adapted to the corresponding mesopic level. However, a necessary parameter to obtain these correction factors is the relationship between the scotopic and photopic light fluxes of a light source (S/P ratio), which requires special equipment that it is not easily available to engineers, technicians and lighting designers. Thus, this paper proposes a general equation that provides the S/P ratio as a function of the correlative color temperature and the color rendering index of the light source, which are information provided in the manufacturers’ catalogs or electric lamp packages. To illustrate the application of the experimentally derived relationship, a typical street lighting project is considered, specifically a retrofit from HPS lamps to modern LED luminaires. In this case, the conventional routine must be changed, allowing the adaptation of conventional quantities to mesopic quantities without need for specialized equipment. The case study evidences that the use of mesopic photometry in conjunction with more appropriate technologies, such as LED luminaires, lead to a higher energy efficiency of the system.
关键词： Scotopic/photopic ratio,Human visual system,Mesopic vision,CIE 191:2010 report,Street lighting,Photometry,outdoor lighting,energy efficiency
更新于2025-09-12 10:27:22
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Effectiveness of an alternative model for establishing mesopic luminance
摘要： To determine mesopic luminance for a given photopic luminance and scotopic/photopic (S/P) ratio, the Commission Internationale de l’Eclairage (CIE) recommended system utilizes an equation. Whilst being accurate, it requires several iterations to achieve a stable result and requires the use of an adaptation coefficient. This article proposes an alternative approach, a model developed using a Rational Taylor function which does not require either iteration or an adaptation coefficient. Road lighting tends to use average photopic luminances in the range of 0.1 to 3 cd/m2; within this range, the model has an average error of 0.28% against the iteration approach, which is sufficient for most practical purposes.
关键词： road lighting,scotopic/photopic ratio,photopic luminance,Rational Taylor function,mesopic luminance
更新于2025-09-09 09:28:46