Difficulties that gamers with color vision deficiencies experience when playing digital games

Sandra Mazur, Jeffery Hovis, and Shankaran Ramaswamy

DOI: 10.1364/JOSAA.544903 Received 16 Oct 2024; Accepted 31 Jan 2025; Posted 31 Jan 2025  View: PDF

Abstract: Research exploring the impact of a color vision deficiency (CVD) on using digital displays in gaming is limited. An online survey was administered to 241 gamers with a CVD (80.1% males) inquiring about their experiences playing digital-based games. Eighty-eight percent (88.0%) experienced at least a little difficulty in playing. The most problematic tasks were “matching colors,” “visibility of objects on a colored background” and “identifying objects based on color.” The genres that were more frequently reported as being difficult to play were “military/paramilitary,” “action-adventure,” and “puzzles.” Most gamers reported using modifications on their displays with at least a little effectiveness.

Dependence of Brightness Induction on the Contrast Polarity of a Disk/Annulus Stimulus

Osman Kavcar, Michael Rudd, and Michael Crognale

DOI: 10.1364/JOSAA.546972 Received 07 Nov 2024; Accepted 30 Jan 2025; Posted 30 Jan 2025  View: PDF

Abstract: Classical theories of brightness and lightness induction have largely been stated in terms of two opposing influences from the surround: contrast and assimilation. In fact, these two effects are part of a more complex, but reproducible and mathematically well-defined statistical process in which both low-level neural constraints and top-down cognitive judgments contribute to the measured percept. Here we test a particular model of this process based on edge integration theory with contrast gain control. We employed a brightness matching technique based on disk/annulus stimuli and show that we can account for our results with a quantitative model in which the contrast polarity of the stimulus plays a critical role.

The 𝜋 phase in polarization optics: a retrospective

Oriol Arteaga and Salvador Bosch

DOI: 10.1364/JOSAA.551750 Received 12 Dec 2024; Accepted 30 Jan 2025; Posted 31 Jan 2025  View: PDF

Abstract: This paper analyzes the 𝜋 phase in polarization optics, tracing its origins to Fresnel’s foundational contributions. In optical experiments involving polarized light, this phase can be interpreted as an indeterminacy arising in two principal forms: (1) as a 𝜋-phase shift affecting only one polarization component, often dictated by convention based on the choice of the coordinate system (e.g., in defining handedness for circularly polarized light), and (2) as a geometric phase that equally influences both polarization components. Unlike the convention-dependent 𝜋-phase, the geometric phase cannot be directly measured using standard polarization techniques and instead emerges through interference effects. Using the Mueller and Jones matrix formalisms, this retrospective study examines the mathematical basis of these phase shifts and their implications in modern optical systems. The analysis underscores the importance of 𝜋 phases in Fresnel’s original work and their relevance to contemporary polarization optics, linking historical concepts to current technological applications.

Dynamic-Static Colour Vision Test - DSCVT

Renars Truksa, Sergejs Fomins, Zane Jansone-Langina, and Laura Tenisa

DOI: 10.1364/JOSAA.545294 Received 16 Oct 2024; Accepted 29 Jan 2025; Posted 30 Jan 2025  View: PDF

Abstract: As part of the research, a computer-based color vision test - DSCVT - was developed, enabling the assessment of color vision using stimulus with static and dynamic luminance contrast noise. Comparing the DSCVT test results to the anomaloscope and CAD tests, the static stimulus version of the DSCVT test demonstrated 100% sensitivity and 82% specificity, while the dynamic test stimulus version achieved 100% sensitivity and specificity. Chromatic sensitivity changes during a lifetime were examined with both DSCVT and CAD tests. Furthermore, when comparing the chromatic thresholds of normal trichromats measured with both DSCVT test stimulus versions, higher chromatic thresholds were observed with the dynamic version compared to the static version. Additionally, statistically significant differences were found of the chromatic thresholds of anomalous trichromats between the two DSCVT test stimulus modifications, although the results are not conclusive due to the small number of participants with color vision deficits.

A tunable broadband terahertz absorber based on a simple design of vanadium dioxide resonator

wang ji, Yao Gu, Fei Liu, Lin Chen, XingChao Wang, and Ke Ji

DOI: 10.1364/JOSAA.546252 Received 29 Oct 2024; Accepted 27 Jan 2025; Posted 28 Jan 2025  View: PDF

Abstract: A tunable broadband terahertz absorber based on five square rings of vanadium dioxide(VO2) is proposed in this paper. We use CST software to simulate the absorption characteristics of the absorber. The results show that the bandwidth of the absorber with absorption exceeding 90% reached 2.51THz from 2.71 to 5.22 THz. The electric and surface current distributions reveal that the high absorption are due to the dipole resonance and coupling of the square rings. The absorption peak can be approximately tuned from 2% to 99.5% by varying the conductivity of VO2 from 200S/m to 200000S/m. In addition, the absorber has polarization insensitivity and can maintain good absorption performance over a wide range of incident angles. The designed absorber is expected to be widely used in areas of terahertz communication, imaging and detector.

Does background color influence perception of facial expression? Adjustment to neutral expression by Caucasian and Japanese participants

Tarja Peromaa, Kaisa Tiippana, Kun Qian, and Maria Olkkonen

DOI: 10.1364/JOSAA.544888 Received 14 Oct 2024; Accepted 25 Jan 2025; Posted 27 Jan 2025  View: PDF

Abstract: Color is linked to emotions, with the strongest link between red and anger. This study primarily addressed whether a red background increases perceived facial angriness, using a method that did not require explicit processing of neither color nor emotional expression, in participants of two ethnicities (Caucasian, Japanese) and genders (female, male). Their task was to adjust the expression on a face to neutral. The face stimuli were image continua of angry, neutral and happy expressions, presented on four background colors (red, saturated red, green, grey). The neutral points were not influenced by background color, nor participants’ ethnicity, suggesting that previous findings showing enhancement of reported facial anger by a red background were likely due to response biases rather than a perceptual effect.

Color screening outcomes on uncalibrated ‘home’ displays – assessment of variability in sRGB color standard parameters on commercial visual displays

Benjamin Evans, Marisa Rodriguez Carmona, Emsal Llapashtica, and John Barbur

DOI: 10.1364/JOSAA.544986 Received 16 Oct 2024; Accepted 23 Jan 2025; Posted 27 Jan 2025  View: PDF

Abstract: The Colour Vision Screener (CVS) test was evaluated for use on visual displays that support the Red Green Blue (sRGB) color space standard. When used on commercial displays in sRGB color mode, the CVS had a sensitivity and specificity [95 percent confidence intervals] of 0.555 (0.461 – 0.644) and 1.00 (0.982 – 1.00). With calibrated displays all color deficient observers failed the CVS, but many of these, some with severe loss, were able to pass the test on 10 separate sRGB displays. The CVS test can only achieve close to 100% sensitivity and specificity on fully calibrated displays.

Statistical method to describe electromagnetic field on the surface of spherical particle of a 2D array

Valery Loiko, Alexander Miskevich, Aliaksandr Hubarevich, and Natalia Loiko

DOI: 10.1364/JOSAA.538231 Received 01 Aug 2024; Accepted 23 Jan 2025; Posted 24 Jan 2025  View: PDF

Abstract: A semi-analytical statistical method has been developed for investigating the near electromagnetic field of a two-dimensional (2D) array of spherical nano- and microparticles. It takes into account multiple scattering of waves in the framework of the quasicrystalline approximation (QCA). Equations are derived to describe (i) ensemble-averaged and (ii) ensemble- and surfaceaveraged energy densities of electric and magnetic fields on the surface of spherical particles embedded in a light-absorbing medium. The method allows one to directly analyze the averaged fields at a known radial distribution function of the array particles. The calculation results are presented for local field enhancement at the wavelengths of the plasmon resonance of silver nanoparticles and the lattice-induced resonance of an ordered array of wavelength-sized silver particles at normal incidence of a plane wave. There is excellent agreement of the results obtained for the highly ordered arrays with small and moderate filling factors with the data of the numerical finite element method (FEM) for perfect arrays of nano- and microparticles. The developed method realization is significantly faster than the used realization of the FEM (up to 250 times).

The Verriest lecture: Color vision from pixels to objects

Karl Gegenfurtner

DOI: 10.1364/JOSAA.544136 Received 08 Nov 2024; Accepted 21 Jan 2025; Posted 22 Jan 2025  View: PDF

Abstract: Scientific investigations of color have traditionally used a pixel-by-pixel approach. By determining the cone excitations of each point in an image, images can be exactly reproduced on different devices by generating metamers. The cone excitations can be used to derive estimates of color appearance under simplified viewing conditions. However, the primary purpose of color perception is not to generate a copy of our surrounding world in our brains. Instead, we propose that color is highly suitable for detection and recognition of objects in our environment, and that it is an entire distribution of color coordinates within an object that defines its color appearance. Here, I review the behavioral, neural and computational mechanisms underlying object and color processing in the natural world.

Hybrid meshes for the modeling of optical nanostructures with the surface integral equation method

Parmenion Mavrikakis and Olivier Martin

DOI: 10.1364/JOSAA.546221 Received 25 Oct 2024; Accepted 20 Jan 2025; Posted 22 Jan 2025  View: PDF

Abstract: Recently, hybrid metasurfaces built from meta-atoms that combine plasmonic and dielectric materials have emerged thanks to their interesting electromagnetic properties. In this study, we resort to surface integral equations (SIEs) and the method of moments (MoM) to model plasmonic and hybrid nanostructures. A surface meshing approach is used to discretize the equations and the Poggio, Miller, Chang, Harrington, Wu, and Tsai (PMCHWT) formulation is considered. To model experimentally-relevant nanostructures efficiently, we combine triangular and quadrilateral elements with Rao-Wilton-Glisson (RWG), rooftop and hybrid basis functions, while an element-by-element approach is used to coalesce triangular and quadrilateral elements. The accuracy and numerical effort associated with each type of mesh are carefully assessed, using a variety of geometries that include one or more materials. Finally, we observe that hybrid meshes are able to accurately reproduce complex scattering features with a significantly reduced number of unknowns.

English colour-term modifiers examined with colour-survey data: Brightness, lightness, paleness and more

David Bimler

DOI: 10.1364/JOSAA.545104 Received 31 Oct 2024; Accepted 19 Jan 2025; Posted 27 Jan 2025  View: PDF

Abstract: Data from an unconstrained colour-naming survey allowed focal points to be located in colour space not just for colour terms but also their modified versions. After converting each modified focus into a displacement from the focus of the unmodified term, the meaning of a given modifier can be operationalised as the bundle of displacements across a range of plain terms; while the dissimilarity between a given pair of modifiers can be calculated as the vector angle between the corresponding bundles. The results for seven basic terms and 12 modifiers, including ‘light’ ‘dark’, ‘pale’, ‘deep’, ‘bright’ and ‘dim’, shows how the use of these terms in colour science departs from their use in common language. I argue that modifiers fall along a gradient of increasing ‘basicness’, analogous to the concept of ‘basic’ for a colour term or category.

Dynamics of S-cone contributions to the initiation of 1 saccadic and smooth pursuit eye movements

Yuan Zhang, giulia agosti, Shuchen Guan, Doris Braun, and Karl Gegenfurtner

DOI: 10.1364/JOSAA.545021 Received 21 Oct 2024; Accepted 19 Jan 2025; Posted 22 Jan 2025  View: PDF

Abstract: We investigated the interplay between luminance and heterochromatic brightness in guiding oculomotor behavior, particularly in saccades and smooth pursuit eye movements. We were particularly interested in testing whether mechanisms for eye target selection incorporate contributions of S-cones. Luminance, typically measured using the CIE’s luminous efficiency function V(λ), has limitations in representing the perceived brightness of heterochromatic stimuli, especially with bluish and yellowish lights. S-cones do not contribute significantly to luminance but do influence brightness perception. To examine the S-cone contributions to oculomotor behavior, we measured target choices of saccades and smooth pursuit between equi-luminant bluish and yellowish stimuli with paradigms producing a wide range of latencies. Our results show that at shorter latencies, luminance primarily drives both eye movements, with equi-luminant bluish and yellowish stimuli chosen equally often. However, as latency increases, participants tend to choose bluish stimuli more frequently, suggesting that heterochromatic brightness plays a larger role in longer-latency eye movements. This indicates that S-cone input may influence target selection as latency increases, highlighting a dynamic interaction between luminance and brightness in oculomotor decisions. We were particularly interested in investigating if the mechanism responsible for eye movement target selection incorporates S-cone activity.

Assessing chromatic discrimination in women using hormonal contraceptives

Galina Paramei, Catherine Ainsworth, and Irene Senna

DOI: 10.1364/JOSAA.545261 Received 16 Oct 2024; Accepted 18 Jan 2025; Posted 21 Jan 2025  View: PDF

Abstract: We explored whether chromatic discrimination is affected in women using hormonal contraceptives (HCs). Leaning upon earlier studies of oral contraceptives (OCs), we reasoned that estrogen and/or progestin, HC components, would reveal mild tritan-like defects in HC users. A sample of 68 women (18–45 years) was stratified by HC type and use history: (a) non-users with past HC use (NCP=21); (b) never used (NC=16); (c) oral contraceptives (OC= ); and (d) long-acting reversible contraceptives (LARC=8). Employed were the D-15, D-15d and the Cambridge Colour Test (CCT). Significant inter-group differences were identified by the D-15d indices and the CCT Trivector measures. The D-15d indices were comparable for users of modern OCs and NC, but higher in the LARC and NCP groups. Furthermore, LARC-users revealed significantly higher Tritan, and also Protan and Deutan thresholds. Conceivably long-acting progestin in LARC down-regulates expression of retinal estrogen receptors implicated in color discrimination.

Old microscopy data reveals optical superresolution in line with information theory

Stefano Selci

DOI: 10.1364/JOSAA.546268 Received 29 Oct 2024; Accepted 18 Jan 2025; Posted 21 Jan 2025  View: PDF

Abstract: This article reexamines a twenty-year-old experiment showing superresolved intensity variations in the far field using visible light, achieved by nanoscale modifications of the diffraction slit spacing. This study was motivated by earlier unexplained far-field microscopy images that achieved λ/10 resolution without near-field operation. Our hypothesis, backed by 2D finite element analysis, proposes that the local illumination of the scanning tip disturbs the intensity transmitted through the diffraction mask, creating super-resolved images through far-field collection of diffracted energy variations. A review of the historical scientific contributions supports this interpretation. We explore the relationship between information theory, space-bandwidth product concepts, and these observations. These findings demonstrate the possibility of achieving far-field optical super-resolution without requiring near-field proximity of the scanning element, potentially enabling new applications across various wavelengths and imaging scenarios.

Evaluation of Participants’ Awareness of Color Vision Deficiency: A Comparative Analysis of Self-Reported Diagnosis and Objective Diagnostic Testing

Zane Jansone-Langina and Renars Truksa

DOI: 10.1364/JOSAA.542465 Received 16 Oct 2024; Accepted 18 Jan 2025; Posted 22 Jan 2025  View: PDF

Abstract: Despite the extensive literature on the challenges faced by people with color vision deficiency (CVD), significant gaps persist in participant awareness of the age of CVD diagnosis. This study aimed to investigate the extent to which participants are aware of CVD, focusing on their understanding of the deficiency. A total of 283 participants participated in a study designed to assess the age at which they became aware of their CVD, what color vision test their diagnosis was based on and the challenges they face. In addition, 190 participants underwent color vision testing using the Color Assessment and Diagnosis (CAD) test, compared to their knowledge of the type of CVD they have. The findings showed that 55% of the participants had found out about their CVD in adulthood, predominantly within occupational contexts. A substantial discrepancy was observed between self-reported diagnoses and clinical findings, with 43% of the participants being unable to specify their type of CVD. There is a necessity for enhanced early diagnostic practices, improved participant education about CVD, and increased public awareness to optimize the quality of life for affected individuals.

Achromatic loci in normal and anomalous trichromats

Fatemeh Basim, Arsiak Ishak, Jesse Macyczko, Erin Goddard, Vanessa Honson, Juno Kim, Kimberly Jameson, and Michael Webster

DOI: 10.1364/JOSAA.546890 Received 08 Nov 2024; Accepted 18 Jan 2025; Posted 22 Jan 2025  View: PDF

Abstract: The stimuli that appear achromatic anchor color space and exhibit multiple properties that reflect an alignment of color vision with spectral characteristics of the chromatic environment. We examined how well this alignment is preserved in individuals with anomalous trichromacy. Observers viewed stimuli spanning a range of chromaticities and luminance contrasts relative to a nominal gray background of varying luminance and classified the stimuli as achromatic (white or gray) or chromatic (one of 8 color terms). For color-normal observers, the achromatic categories were constrained in size and tended to vary along a blue-yellow axis with a bias toward blue. Anomalous observers had larger achromatic regions and less evidence for a blue-yellow orientation. However, the range of stimuli labeled as achromatic was often substantially smaller than the range predicted by their threshold sensitivity losses. This discrepancy is consistent with partial compensation of color perception for the altered spectral sensitivities of anomalous trichromats.

Dual-function Switchable terahertz metamaterials devices assisted by deep neural network

Jiali Ren, Ting Zhang, and Jing Li

DOI: 10.1364/JOSAA.547470 Received 08 Nov 2024; Accepted 17 Jan 2025; Posted 23 Jan 2025  View: PDF

Abstract: A broadband absorption and polarization conversion dual-functional switchable terahertz metamaterials (THz MMs) devices is proposed, utilizing the insulator-metal phase transition of vanadium dioxide (VO₂). In its metallic state, the device functions as an absorber, achieving a bandwidth of 3.93 THz within the range of 2.53 to 6.46 THz, with an absorption rate of ≥90%. In its insulating state, the device operates as a polarization converter, offering two conversion modes: linear-to-cross-polarization (LTX) in the range of 1.17 to 3.63 THz, and linear-to-circular polarization (LTC) in the ranges of 1.04 to 1.14 THz and 3.71 to 3.87 THz. Compared to other multifunctional devices, this design offers the broadest overlapping bandwidth. Furthermore, a deep neural network (DNN) was employed to efficiently optimize the structural parameters. The proposed dual-functional switchable THz MMs devices, with its exceptional broadband absorption and polarization conversion capabilities, serves as a valuable reference for the development of new multifunctional THz devices.

Visual Judgement of Food Attributes under Near-Metameric Illumination Changes

Ilgin Cebioglu, Mya Mistry, Rebecca Vasey, and Anya Hurlbert

DOI: 10.1364/JOSAA.544988 Received 16 Oct 2024; Accepted 10 Jan 2025; Posted 10 Jan 2025  View: PDF

Abstract: Food colour is a useful visual signal of vital food attributes, e.g. ripeness (yellow) or rottenness (brown) in a banana. Previous studies of the effects of colour appearance on perceived food quality have typically used 2D images and confounded appearance changes with other factors. Here we alter the colour appearances of six naturalistic 3D fruits/vegetables using near-metameric illumination changes, keeping constant all physical object properties and context. Although participants’ ratings of perceived food attributes vary between objects and individuals, the results validate the illumination manipulation technique and demonstrate that colour appearance changes alone may drive significant changes in perceived food quality.

Comparison of intermodulation and oddball methods for measuring human cortical color tuning 2 functions using steady-state visually evoked potentials

Ana Rozman, Chris Racey, and Jenny Bosten

DOI: 10.1364/JOSAA.545280 Received 16 Oct 2024; Accepted 08 Jan 2025; Posted 24 Jan 2025  View: PDF

Abstract: Characterization of postreceptoral chromatic mechanisms is an active challenge in color vision 8 research. Adding to evidence from human psychophysics and primate neurophysiology, human 9 neuroimaging using electroencephalography (EEG) in combination with steady-state visually evoked 10 potentials (SSVEPs) has recently been used to investigate the tuning of cortical color mechanisms. We 11 compare the performance of two SSVEP-based methods for measuring the tuning of cortical color 12 mechanisms: an intermodulation component (IM)-based method, and an oddball method. Our results 13 support SSVEPs as an effective tool for investigating the tuning of cortical color mechanisms. The 14 intermodulation method is efficient and provides high signal-to-noise, but the oddball method can 15 also yield clear tuning functions if multiple SSVEP harmonics are analyzed in combination.

Gated Amplification of Spectrally-Tuned Channels: A Neurally Motivated Potential Mechanism for the Broadened Spectral Sensitivities of Pi4, Pi5 and Chromatic Brightness

Vincent Billock, Erica Poole, and Adam Preston

DOI: 10.1364/JOSAA.545287 Received 16 Oct 2024; Accepted 07 Jan 2025; Posted 08 Jan 2025  View: PDF

Abstract: Chromatic brightness resembles luminance spectral sensitivity, but is broader, an effect usually attributed to nonlinear combination of luminance and hue channels. Similarly, Stiles’ Pi4 and Pi5 mechanisms resemble M-cone and L-cone spectral sensitivities, but Pi4 is broader at long wavelengths and Pi5 is broader at short wavelengths, effects attributed to contributions of L-cones to Pi4 and contributions of M-cones to Pi5. All three spectral broadenings can be modeled by a neurally-motivated gated amplification mechanism (found in monkeys, cats and rattlesnakes) that obeys a simple power law. The amplification of luminance into chromatic brightness has a compressive exponent of about 0.85, with similar compressive exponents for amplification of M-cones to Pi4 and amplification of L-cones to Pi5 (with Pi5 the least compressive). For compressive exponents, low spectral sensitivities are amplified relatively more than high ones (but only when the second “gating” channel is activated)

A method for quantifying loss of central and peripheral color discrimination with tinted lenses

Andrew Coia, Andrew Mojica, Christopher Bartak, Joseph Arizpe, and Alan Ashworth

DOI: 10.1364/JOSAA.545509 Received 18 Oct 2024; Accepted 06 Jan 2025; Posted 07 Jan 2025  View: PDF

Abstract: In addition to blocking laser threats, laser eye protection (LEP) can cause color confusions for pilots. We developed and validated a novel method of measuring LEP effects on the discrimination, detection, and localization of chromaticity differences corresponding to yellow and white in the central and peripheral visual fields. Signal Detection Theory measures of sensitivity and response bias were calculated. The central LEP condition resulted in significantly worse performance than a No LEP condition, but with enough contrast discrimination with LEP was achieved. The peripheral task showed a same color bias and discrimination was close to chance even at maximum contrast.

Grover-Sagnac interferometer

Christopher Schwarze, Anthony Manni, David Simon, Abdoulaye Ndao, and Alexander Sergienko

DOI: 10.1364/JOSAA.549928 Received 22 Nov 2024; Accepted 03 Jan 2025; Posted 07 Jan 2025  View: PDF

Abstract: We demonstrate a nontraditional design of the Sagnac interferometer by replacing the commonly used beam splitter with a linear-optical Grover multiport. This substitution creates a pole at the origin of the device parameter space with an associated resonance in the output intensity. The structure of this resonance is dictated only by the non-reciprocal portion of the phase acquired in the Sagnac loop. This property directly results from adopting the more symmetric and higher-dimensional central scattering coin, and allows for a different approach to registering and detecting the non-reciprocal Sagnac phase. This parameter may be extracted from the width of a peak or dip in the interferogram instead of tracing small changes in power as in traditional Sagnac interferometry. We discuss how losses affect the system and potential metrological applications.

Propagation characteristics of partially coherent twisted off-axis double-vortex beams in atmospheric turbulence

qinghai wang, MENG ZHANG, shaohua Zhang, and Jun Qu

DOI: 10.1364/JOSAA.549258 Received 15 Nov 2024; Accepted 01 Jan 2025; Posted 03 Jan 2025  View: PDF

Abstract: We propose a partially coherent twisted off-axis double vortex (PCTODV) beam and investigate its propagation characteristics in atmospheric turbulence. By employing the extended Huygens-Fresnel principle and the Wigner distribution function, we derive the corresponding analytical expressions and perform numerical simulations to validate our findings. The findings reveal that PCTODV beams possess a wider array of tunable parameters than single vortex beams with central phase singularities, which is beneficial for atmospheric turbulence propagation. The twist factor size notably affects the beam evolution rate in turbulence, with an optimized twist factor enhancing resistance to turbulence. Moreover, factors such as increased wavelength, larger initial beam waist, greater inner turbulence scale, higher refractive index structure constant, and reduced M2 factor contribute to improved transmission stability. These insights advance the understanding of vortex beam propagation in turbulent atmospheric optical communication systems.

Multi-centre evaluation of the Colour Vision Screener test

Benjamin Evans, Marisa Rodriguez Carmona, Franziska Rauscher, Emsal Llapashtica, Vilhelm Koefoed, Focke Ziemssen, Rudolph Nitsche, Alessandro Farini, Elisabetta Baldanzi, Luis Robledo, Amanda Douglass, Madeline Baker, Roland Quast, Sabine Roelcke, Steven Ho, and John Barbur

DOI: 10.1364/JOSAA.544985 Received 16 Oct 2024; Accepted 28 Dec 2024; Posted 07 Jan 2025  View: PDF

Abstract: An international multicenter study was designed and carried out to evaluate the color vision screener (CVS) test for normal trichromats and congenital color deficients. Over 400 participants from nine international Colour Assessment and Diagnosis (CAD) testing centers completed the CVS and the CAD test on calibrated visual displays. The CVS had a sensitivity and specificity [95 percent confidence intervals] of 1.00 [0.985-1.00] and 0.994 [0.969-0.999] with a positive and negative predictive index of 0.940 and 1.00 for an assumed prevalence of 8 percent. The CVS is quick, efficient, easy to use, and its sensitivity is equivalent to the optimal published Ishihara protocol.

Modeling wavelengths and spectral half power bandwidths for Rayleigh equation anomaloscopes

Stephen Dain and Jeffery Hovis

DOI: 10.1364/JOSAA.545024 Received 16 Oct 2024; Accepted 28 Dec 2024; Posted 03 Jan 2025  View: PDF

Abstract: The recommended and required wavelengths for Rayleigh equation anomaloscopes are many and varied and without a numerical evidence base. The requirements for spectral half power bandwidth in the German standard DIN 6160 also have no known evidence base. This paper provides data to establish requirements. The constraint on the short wavelength limit of green was assessed by plotting chromaticities for a range of wavelengths and spectral half power bandwidths and limiting the results to within the first half of the deuteranopic (green and yellow) or protanopic (red) confusion zone. The other wavelength limits were assessed by modeling the match point and matching range using the normal and anomalous photopigment data of DeMarco, Pokorny and Smith (1992). The proposed wavelength limits are expressed as chromaticity and equivalent wavelength and spectral half power bandwidth limits. The wavelength limits are less restrictive than in DIN 6160.

Impact of Field of View on Color Constancy in Virtual Reality

Killian Duay and Takehiro Nagai

DOI: 10.1364/JOSAA.544170 Received 07 Oct 2024; Accepted 26 Dec 2024; Posted 03 Jan 2025  View: PDF

Abstract: Recent advances in virtual reality (VR) and head-mounted display (HMD) color calibration offer a novel framework for vision science, enabling researchers to investigate color constancy from new perspectives. The aim of this study was to assess the effectiveness of VR in color constancy studies by investigating how field of view and scene complexity, two variables that take advantage of VR's unique features, influence color constancy. We conducted a VR psychophysical experiment in which observers were asked to judge the color of patches under various conditions. The results showed that field of view has a strong and significant impact on color constancy. However, no significant differences were found between complex and simpler scenes. These findings demonstrate the potential of VR as a valuable tool for investigating the interaction between unique VR features, such as an expanded field of view, and color constancy.

Polarization state control for high peak power applications

Ekaterina Starodubtseva, Ivan Cymbalov, Diana Gorlova, Konstantin Ivanov, and Andrei Savelev

DOI: 10.1364/JOSAA.544487 Received 21 Oct 2024; Accepted 23 Dec 2024; Posted 24 Dec 2024  View: PDF

Abstract: The use of circularly polarized high peak power ultrashort pulses has various applications in extreme field science. Commonly used quarter-wave plates are unsuitable here, while multi-mirror schemes are technically complicated. We have demonstrated that the simple PET film 20.5 μm thick can be used to manipulate the polarization state of the high peak power beam and achieve ellipticity of up to 0.8 with negligible nonlinear phase distortion. Furthermore, the film can withstand 10³ shots at the intensity of I = 3·10¹² W/cm² without sustaining visible damage. Thus, PET film is suitable for long-term use in a PW laser system with a 20 cm beam diameter. We confirmed this experimentally by measuring the angular distribution of the second harmonic from the plasma channel created in an undercritical gas plume with a 1 TW femtosecond Ti:Sa laser.

The effect of stimulus size on chromatic discrimination

Marina Danilova and John Mollon

DOI: 10.1364/JOSAA.545292 Received 21 Oct 2024; Accepted 22 Dec 2024; Posted 24 Dec 2024  View: PDF

Abstract: Colour discrimination requires observers to compare the spectral power distributions of two discriminanda. This paper reports the results of psychophysical experiments where discrimination thresholds were measured in different directions from points in the MacLeod-Boynton chromaticity diagram under conditions of constant adaptation to a metamer of D65. The data were fitted with ellipses. Several areas in the diagram were probed using a forced-choice procedure: the observers were presented with a brief 150 ms disc divided in four sectors and the task was to detect one sector that differed from the other three. The diameter of the test disc varied from 32 min to 2.4 deg in diameter. Ellipses of the largest tested size (2.4 deg diameter) were predominantly oriented so that their longer axis was aligned with the line connecting the chromaticity of D65 (adaptation point) and the centre of the ellipse. Along such lines, colorimetric purity varies, and the orientation of the ellipses reflects reduced sensitivity to saturation differences compared to hue differences. With decreasing test size, the ellipses change their orientation so that their longer axis is rotated towards the tritan line and the detection of changes in chromaticity is dependent mostly only on the activity of long- and middle--wave cones.The changes in orientation and shape depend, however, on the location of the ellipse in the diagram. (i) Ellipses centred on the tritan line through D65 with low S-cone input are circular for large stimuli, but they are elongated and become aligned with the tritan line for smaller ones; ellipses with high S-cone input change their orientation from being aligned with tritan line for the largest size to being slightly rotated away from the line with decreasing stimulus size. (ii) Ellipses with their centres on the line connecting unique blue and unique yellow with low S-cone input do not change their orientation, but they are not aligned exactly with the colorimetric purity line. (iii) Ellipses centred on the horizontal line through D65 are elongated along this line for larger sizes and become more circular with decreasing stimulus size.

Visual search for warm and cool colors

Jake Manalansan, Camilla Simoncelli, and Michael Webster

DOI: 10.1364/JOSAA.545307 Received 16 Oct 2024; Accepted 21 Dec 2024; Posted 03 Jan 2025  View: PDF

Abstract: Warm vs cool colors are considered a fundamental aspect of color experience, yet the basis for this distinction remains poorly understood. Recently we found that the warm-cool dimensions is closely aligned with sensitivity biases that implicit in uniform color spaces (Manalansan and Webster, in review). Here we directly tested for these biases by measuring visual search for color targets on backgrounds defined by different axes in color space. The search task involved locating a circular chromatic target sampled from a fixed range of chromaticities that was presented on a dense background of ellipses whose chromatic contrasts randomly varied along the warm-cool (roughly orange-cyan) or blue-yellow axis or two axes representing the orthogonal (magenta-greenish) color directions. Search times were faster on both warm-cool and blue-yellow backgrounds than the orthogonal backgrounds. However, there was not a difference between these two axes, or for warm vs. cool hues or blue vs. yellow hues. These results are consistent with weaker salience for the warm-cool and blue yellow axes of color space, but do not reveal a salience difference between colors more strongly associated with objects and surfaces (warn and yellow) versus backgrounds and illumination (cool and blue).