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The International Society for Clinical Electrophysiology of Vision (ISCEV) standard for full-field electroretinography (ERG) describes a minimum procedure for testing generalized retinal function but encourages more extensive testing. This extended protocol describes a method of assessing the function of the short-wavelength-sensitive cone (S-cone) retinal pathway, using a short-wavelength flash superimposed on a background that saturates the rods and adapts the L/M-cones to elicit a response, known as the S-cone ERG. Stimulus parameters such as the strength and luminance of the flash and background, respectively, and their spectral and temporal characteristics are specified. As a complement to the ISCEV standard, testing the S-cone ERG enables further characterization of light-adapted retinal function and may refine diagnosis of some retinal disorders. Typical applications are described including use in the diagnosis of rod monochromacy and S-cone monochromacy, identification and investigation of cone On-bipolar cell dysfunction and use of the technique to confirm the diagnosis of enhanced S-cone syndrome.

Color blindness is when someone is unable to see color in a normal way or make out the differences in certain colors. The color-sensitive cells in our eyes react differently to various wavelengths of light giving our brain the information needed to create the ‘perceived’ color in our vision. There is no way to rectify the cells. In other words, color blind people cannot be treated. This paper uses image processing techniques to make Ishihara Test (test for color deficiency) images visible to partially and totally color blind people. Authors have targeted the following types of dichromatic color blindness—deuteranopia, protanopia, tritanopia and also monochromatic color blindness. All of this is achieved by applying various state-of-the-art image processing and mathematical operations in the image pixels to allow the user to ‘perceive’ the color as it was intended. To give a kind of proof of concept of the image processing for complete color blindness, a machine learning model has been implemented and trained on the widely known MNIST dataset.

Bats are a diverse radiation of mammals of enduring interest for understanding the evolution of sensory specialization. Colour vision variation among species has previously been linked to roosting preferences and echolocation form in the suborder Yinpterochiroptera, yet questions remain about the roles of diet and habitat in shaping bat visual ecology. We sequenced OPN1SW and OPN1LW opsin genes for 20 species of leaf-nosed bats (family Phyllostomidae; suborder Yangochiroptera) with diverse roosting and dietary ecologies, along with one vespertilionid species (Myotis lavali). OPN1LW genes appear intact for all species, and predicted spectral tuning of long-wavelength opsins varied among lineages. OPN1SW genes appear intact and under purifying selection for Myotis lavali and most phyllostomid bats, with two exceptions: (a) We found evidence of ancient OPN1SW pseudogenization in the vampire bat lineage, and loss-of-function mutations in all three species of extant vampire bats; (b) we additionally found a recent, independently derived OPN1SW pseudogene in Lonchophylla mordax, a cave-roosting species. These mutations in leaf-nosed bats are independent of the OPN1SW pseudogenization events previously reported in Yinpterochiropterans. Therefore, the evolution of monochromacy (complete colour blindness) has occurred in both suborders of bats and under various evolutionary drivers; we find independent support for the hypothesis that obligate cave roosting drives colour vision loss. We additionally suggest that haematophagous dietary specialization and corresponding selection on nonvisual senses led to loss of colour vision through evolutionary sensory trade-off. Our results underscore the evolutionary plasticity of opsins among nocturnal mammals.

Color blind is a type of Color Vision Deficiency, which is the inability that a person could not realize the differences between some colors. There are three types of color blindness: Monochromacy, Dichromacy, and Anomalous Trichromacy. Color blind cannot be cured. Today, technology gets up with solutions to help people with color blindness to see the image and distinguish between the different colors using some algorithms. This paper presents a smartphone based experimental comparison of color correction algorithms for all Dichromacy color-blind viewers: Protanopia, Duteranopia, and Tritanopia. This comparison includes LMS Daltonization algorithm, Color-blind Filter Service (CBFS) algorithm, LAB color corrector algorithm, and the shifting color algorithm. The LMS algorithm is implemented for all the three types of Dichromacy. While CBFS, LAB adjustment, and Shifting color algorithms are applied to correct colors for Protanopia, Duteranopia, and Tritanopia respectively. The results show that the processing time for LMS algorithm is slow compared to other algorithms. For Protanopia people, the LMS algorithm is better than CBFS algorithm as the LMS algorithm only changes color of con-fused areas with no change in the brightness. For Duteranopia people, the LAB color correction is better than the LMS algorithm. For Tritanopia people, both the shifting color algorithm and the LMS algorithm may produce a new confu-sion in the proceed images. An application interface is implemented to enable the user to choose the algorithm that gives the most appropriate results.

Colour vision in the marine environment is on average simpler than in terrestrial environments with simple or no colour vision through monochromacy or dichromacy. Monochromacy is found in marine mammals and elasmobranchs, including whales and sharks, but not some rays. Conversely, there is also a greater diversity of colour vision in the ocean than on land, examples being the polyspectral stomatopods and the many colour vision solutions found among reef fish. Recent advances in sequencing reveal more opsin (visual pigment) types than functionally useful at any one time. This diversity arises through opsin duplication and conversion. Such mechanisms allow pick-and-mix adaptation that tunes colour vision on a variety of very short non-evolutionary timescales. At least some of the diversity in marine colour vision is best explained as unconventional colour vision or as neutral drift.

This paper proposes a recoloring algorithm that when applied to images and videos, recolors them such that the color vision deficient users are able to see things that they previously couldn't. We compare the performances of two other prominent recoloring algorithms and prove how the proposed contrast enhancement color compensation technique is the most efficacious. Our previous paper [7] discusses color blindness, its causes and effects, the research that had been done previously on mitigating it, their outcomes and the various approaches adopted by some of the eminent researchers in this field. Color blindness is the inability of its victim to differentiate between the objects whose colors lie in a specific range of wavelengths, specific for each and every type of color blindness. Its three types are monochromacy, dichromacy and trichromacy. Our work focuses on anomalous trichromacy (especially on deuteranomaly and tritanomaly). While there is no medical cure for it yet, defective vision can be assuaged by certain techniques which many researchers have come up with. The merits and demerits of the various author's approaches were discussed in our previous [5] publication. Most of the research work that had been done never accounted for videos. We implement the previously invented algorithms on videos as well, thereby making a significant breakthrough. Apart from that, we propose a novel recoloring algorithm that is also applicable on both.

Color Blindness which can be also referred as Color Vision Deficiency (CVD) is one of the biggest scaling defect in humans which is still under the research for its accurate detection and cure measures & strategies. Color Blindness is the decreased ability to sight the distinctive colors instantly under normal lighting conditions. There are approximately 250 million individuals who suffer from Color Blindness. So it is need of an hour to understand all the important aspects of the Problem CVD and take the necessary measures to help the People who are knowingly or unknowingly suffering from CVD. In this paper we are going to put light on how exactly color blindness is genetically transferred to children, types in color vision deficiency i.e. Anomalous Trichromacy (protanomaly, deuteranomaly, tritanomaly), Monochromacy and how exactly person sees the normal image under respective CVD and finally put light on few algorithms and strategies which with the help of re-coloring and wavelength shifting actually help the color vision deficient to view and sight all the colors of the actual image distinctively.

We established a protocol using a well-established LED stimulator to measure temporal contrast sensitivities driven by sine-wave modulation of L- and M-cones in the perifovea using triple silent substitution. The stimulus was presented in an annular field (2° inner diameter, 13° outer diameter). We validated this technique by studying the contrast sensitivity of three color normal observers at 10 different temporal frequencies (between 1 and 28 Hz) over a large range of retinal illuminances (between 0.07 and 587 phot Td), spanning the complete mesopic range. In one subject, sensitivities to counterphase modulation of L- and M-cones and in-phase modulation of L, M, and S-cones were additionally measured, which putatively reflected the parvo- and magnocellular retinogeniculate pathways, respectively. Furthermore, we performed measurements of temporal contrast sensitivities as a function of frequency at 294 phot Td in two protanopes, in two deuteranopes, and in one subject with S-cone monochromacy. Quality of isolation was satisfactory and we were able to reproduce known physiological patterns of temporal vision, such as the typical temporal contrast sensitivity functions of the L- and M-cone, the parvo- and magnocellular retinogeniculate pathways, as well as the light adaptation curves. These results will help determine optimal stimulus conditions in future studies. Results from the dichromats and the S-cone monochromat also support the quality of isolation of our protocol and underpin its potential clinical value.

X-linked cone photoreceptor disorders caused by mutations in the OPN1LW (L) and OPN1MW (M) cone opsin genes on chromosome Xq28 include a range of conditions from mild stable red-green colour vision deficiencies to severe cone dystrophies causing progressive loss of vision and blindness. Advances in molecular genotyping and functional analyses of causative variants, combined with deep retinal phenotyping, are unravelling genetic mechanisms underlying the variability of cone opsin disorders.

Research conducted in recent years has documented the widespread presence of various forms of color vision in species from across the animal kingdom, helped to develop an understanding of the basic biological mechanisms that underlie this sensory capacity, and provided some insights into the utility of color vision in the natural world. This chapter draws information from all these various sources to reveal what has been learned about the evolution of color vision. In doing so, we examine the extent and nature of animal color vision, describe various structural features of eyes and photoreceptors that condition color vision, look at photopigment opsin genes and their color vision concomitants, and comment on specific cases where progress has been made toward understanding the functional utility of color vision. Although results from a wide range of different species are considered, we focus particular attention on issues relevant to the evolution of vertebrate color vision.