Dissociation between red and white stimulus perception: A perimetric quantification of protanopic color vision deficiencies

Significance Horizontal visual field extension was assessed for red and white stimuli in subjects with protanopia using semi-automated kinetic perimetry. In contrast to a conventional anomaloscope, the “red/white dissociation ratio” (RWR) allows to describe protanopia numerically. For the majority of subjects with protanopia a restriction for faint red stimuli was found. Purpose Comparing the horizontal visual field extensions for red and white stimuli in subjects with protanopia and those with normal trichromacy and assessing the related intra-subject intra-session repeatability. Methods The subjects were divided into groups with protanopia and with normal trichromacy, based on color vision testing (HMC anomaloscope, Oculus, Wetzlar/FRG). Two stimulus characteristics, III4e and III1e, according to the Goldmann-classification, were presented with semi-automated kinetic perimetry (Octopus 900 perimeter, Haag-Streit, Köniz/CH). They moved along the horizontal meridian, with an angular velocity of 3°/s towards the visual field center, starting from either the temporal or nasal periphery. If necessary, a 20° nasal fixation point offset was chosen to capture the temporal periphery of the visual field. For each condition the red/white dissociation ratio (RWR); Pat Appl. DPMA DRN 43200082D) between the extent of the isopter for red (RG610, Schott, Mainz/ FRG) and white stimuli along the horizontal meridian was determined. Results All data are listed as median/interquartile range: Five males with protanopia (age 22.1/4.5 years) and six males with normal trichromacy (control group, age 30.5/15.2 years) were enrolled. The RWR is listed for the right eye, as no clinically relevant difference between right and left eye occurred. Protanopes’ RWR for mark III4e (in brackets: control group) was 0.941/0.013 (0.977/0.019) and for mark III1e 0.496/0.062 (0.805/0.051), respectively. Conclusions In this exploratory “proof-of-concept study” red/white dissociation ratio perimetry is introduced as a novel technique aiming at assessing and quantifying the severity of protanopia. Further effort is needed to understand the magnitude of the observed red-/white dissociation and to extend this methodology to a wider age range of the sample and to anomalous trichromacies (protanomalia) with varying magnitude.

A Novel Approach to Image Recoloring for Color Vision Deficiency

In this paper, a novel method to modify color images for the protanopia and deuteranopia color vision deficiencies is proposed. The method admits certain criteria, such as preserving image naturalness and color contrast enhancement. Four modules are employed in the process. First, fuzzy clustering-based color segmentation extracts key colors (which are the cluster centers) of the input image. Second, the key colors are mapped onto the CIE 1931 chromaticity diagram. Then, using the concept of confusion line (i.e., loci of colors confused by the color-blind), a sophisticated mechanism translates (i.e., removes) key colors lying on the same confusion line to different confusion lines so that they can be discriminated by the color-blind. In the third module, the key colors are further adapted by optimizing a regularized objective function that combines the aforementioned criteria. Fourth, the recolored image is obtained by color transfer that involves the adapted key colors and the associated fuzzy clusters. Three related methods are compared with the proposed one, using two performance indices, and evaluated by several experiments over 195 natural images and six digitized art paintings. The main outcomes of the comparative analysis are as follows. (a) Quantitative evaluation based on nonparametric statistical analysis is conducted by comparing the proposed method to each one of the other three methods for protanopia and deuteranopia, and for each index. In most of the comparisons, the Bonferroni adjusted p-values are <0.015, favoring the superiority of the proposed method. (b) Qualitative evaluation verifies the aesthetic appearance of the recolored images. (c) Subjective evaluation supports the above results.

Dyschromatopsy, Achromatopsia and Blue Cone Monochromatism; Pathophysiology, Clinical Findings, Diagnosis, and Treatment

Color vision is a complex perception caused by the stimulation of cone photoreceptors in the retina and the perception of this stimulation in the brain. Hereditary color vision deficiencies are caused by a defect in the functions of cone cells. Color vision deficiencies are named according to three different types of pigments contained in cones. These disorders, which are seen in high prevalence worldwide, are found more frequently in males. Contrary to thought, colored vision defects often affect daily life. Although it can be easily diagnosed with color vision tests and electrophysiological tests, current treatment options are limited and its success rate is low.

Plasticity in perception: insights from color vision deficiencies

Inherited color vision deficiencies typically result from a loss or alteration of the visual photopigments absorbing light and thus impact the very first step of seeing. There is growing interest in how subsequent steps in the visual pathway might be calibrated to compensate for the altered receptor signals, with the possibility that color coding and color percepts might be less severely impacted than the receptor differences predict. These compensatory adjustments provide important insights into general questions about sensory plasticity and the sensory and cognitive processes underlying how we experience color.

Specificity of the chromatic noise influence on the luminance contrast discrimination to the color vision phenotype

Many studies have examined how color and luminance information are processed in the visual system. It has been observed that chromatic noise masked luminance discrimination in trichromats and that luminance thresholds increased as a function of noise saturation. Here, we aimed to compare chromatic noise inhibition on the luminance thresholds of trichromats and subjects with severe deutan or protan losses. Twenty-two age-matched subjects were evaluated, 12 trichromats and 10 with congenital color vision impairment: 5 protanopes/protanomalous, and 5 deuteranopes/deuteranomalous. We used a mosaic of circles containing chromatic noise consisting of 8 chromaticities around protan, deutan, and tritan confusion lines. A subset of the circles differed in the remaining circles by the luminance arising from a C-shaped central target. All the participants were tested in 4 chromatic noise saturation conditions (0.04, 0.02, 0.01, 0.005 u′v′ units) and 1 condition without chromatic noise. We observed that trichromats had an increasing luminance threshold as a function of chromatic noise saturation under all chromatic noise conditions. The subjects with color vision deficiencies displayed no changes in the luminance threshold across the different chromatic noise saturations when the noise was composed of chromaticities close to their color confusion lines (protan and deutan chromatic noise). However, for tritan chromatic noise, they were found to have similar results to the trichromats. The use of chromatic noise masking on luminance threshold estimates could help to simultaneously examine the processing of luminance and color information. A comparison between luminance contrast discrimination obtained from no chromatic and high-saturated chromatic noise conditions could be initially undertaken in this double-duty test.

Prevalence of Color Vision Deficiencies

Purpose. The study of color deficiencies prevalence in young people, students of higher educational university.Materials and methods. The study was carried for the half year — fall semester. A total of 1,609 students were examined, aged 17–21. There were 1191 boys and 418 girls. The survey was conducted to determine the health groups in physical training and in various sports sections. An ophthalmologic examination determined refractive disorders and other ocular pathology, which is important for determining health groups. Rabkin polychromatic tables and Neitz color vision test (Neitz Lab (UW Medicine) were used for determining of color deficiencies. The obtained results of these tests were compared in terms of the time spent on the test, the results of the test effectiveness, the determination of dissimulation, and the assessment of the shift in the color spectrum in individuals with impaired color perception.Results. A total of refractive disorders were detected in 856 students (53.2 %). The high degree of myopia was in 40. Disorders of color deficient were noted in 101 students (8.48 %) of 1191 male subjects when using the Neitz color test. Dichromatic eye changes were observed from 2.1 % students: protanopia and deiteranopia were in 0.67 % and 1.43 %. Most of all there were violations with the perception of shades of light brown and light green colors. A third of healthy students noted the impossibility of distinguishing light brown from light gray. This is regardless of the state of refraction. Simultaneous violations of the perception of shades of red, green, yellow and blue were observed in one subject, it was associated with congenital cataracts. In four young people, acquired eye diseases caused. In two girls, violations of the perception of a pastel shade of light green were noted, with one girl (0.24 %) having a violation in two eyes, and was presumably due to a gene anomaly. The second girl had one eye and was associated with partial atrophy of the optic nerve after the optic neuritis.Conclusions. Neitz color test expands the diagnostic possibilities, since in its design it has pastel shades of light green and light brown colors on a gray background, reduces the likelihood of dissimulation, reduces the time of the survey. Neitz color test allows to expand the possibilities for more accurate and differential diagnosis dichromatic and anormal trichromatic subjects and acquired color vision defects.

Robust Color Maps That Work for Most Audiences (Including the U.S. President)

&lt;p&gt;Color is an integral element in many visualizations in (geo-)sciences, specifically in maps but also bar plots, scatter plots, or time series displays. Well-chosen colors can make graphics more appealing and, more importantly, help to clearly communicate the underlying information. Conversely, poorly-chosen colors can obscure information or confuse the readers. One example for the latter gained prominence in the controversy over Hurricane Dorian: Using an official weather forecast map, U.S. President Donald Trump repeatedly claimed that early forecasts showed a high probability of Alabama being hit. We demonstrate that a potentially confusing rainbow color map may have attributed to an overestimation of the risk (among other factors that stirred the discussion).&lt;/p&gt;&lt;p&gt;To avoid such problems, we introduce general strategies for selecting robust color maps that are intuitive for many audiences, including readers with color vision deficiencies. The construction of sequential, diverging, or qualitative palettes is based on on appropriate light-dark &quot;luminance&quot; contrasts while suitably controlling the &quot;hue&quot; and the colorfulness (&quot;chroma&quot;). The strategies are also easy to put into practice using computations based on the so-called Hue-Chroma-Luminance (HCL) color model, e.g., as provided in our &quot;colorspace&quot; software package (http://hclwizard.org), available for both the R and Python programming languages. In addition to the HCL-based color maps the package provides interactive apps for exploring and modifying palettes along with further tools for manipulation and customization, demonstration plots, and emulation of visual constraints.&lt;/p&gt;