Theory Of Color Vision Research Articles

Editorial

Editorial

The retinex of colour vision impairment

AbstractThe concept of the “Retinex” was introduced by Edwin Land in 1962. The aim of his theory of colour vision was to highlight the observations on colour perception that were at odds with the simple “Newtonian” concept that the colours that humans perceive when viewing narrow band light are directly related to perceived colours in the environment. There are, however, two particular observations which are at odds with this simple interpretation of the colours seen in the “spectrum” of light. One was emphasized by Gӧethe in his colour theory: namely that there are a range of named colours that are influenced by the luminance contrast (e.g. brown which is a darkened orange) or closeness of the colour to white. This was explored by Chevreul, Munsell and others who developed systems of colour based on the three dimensions: hue (colour category), saturation (closeness to white) and value (brightness). The second was the observation studied extensively by Land: namely that colours remain constant across a certain range despite a change in the spectral content of the illuminant. Thus despite a change in the pattern of cone excitation the colour appearance does not change. Land also emphasized that this phenomenon is influenced by other colours in the scene and introduced the study of natural scenes with natural illumination rather than narrow band light in the laboratory.So in this context Land decided to refer to the “Retinex” as it was clear that the various processes were taking place both at the retinal and cortical levels. I am adopting this term in my talk because clinical studies provide an opportunity to study the influence of damage at all levels in the visual pathway on colour perception. Beginning with congenital colour anomalies affecting the cone opsins all the way to damage to extra‐striate visual cortex clinical studies, such as those presented in this symposium, alterations in colour vision provide an insight into how damage at various levels in the “Retinex” influence colour perception.

9.4: Plasmonic Nanostructure‐Loaded filtering film for Color Blindness Management

Optimization of filters for color blindness management was investigated to improve color vision on display devices. A model for simulation of CVD was built based on display primaries, twostage theory of human color vision and spectral filtration of filters. Spectral filtration of filters made of dye, nanostructures and multi‐layer dielectric filters was surveyed with varying primaries. Quantitative evaluation system of color contrast and naturalness were introduced into filter studies to optimize perceptual experience in both personal and public display products.

Biophysical aspects of electromagnetic theory of human vision perception of light information in the visible range

Objective. To propose an electromagnetic model for human recognition of light information received by a man in the visible range of light, which allows to prove its consistency strictly and based on the calculations made, as well as models of electronic circuits illustrating how simple connections between rods and cones can ensure its implementation, and construct a hypothesis about the transmission of converted information in real-time to the central nervous system on their basis. The goal also includes proposing a hypothesis for the volumetric perception of external information by the visual analyzer and the central nervous system.Materials and methods. Mathematical modeling of data approximation in biology and medicine of numerical values of parameters according to experimental data, a set of formulas and equations that describe the properties of the object under study and allow establishing quantitative relationships between them.Results. The model developed by the authors of electromagnetic perception of electromagnetic waves of the visible spectrum by human vision based on their resonant separation and amplification allows us to propose a solution to the theory of color vision. The given speed calculations based on the saltatory conduction of information from the nerve fiber explain the human subjective feeling of light almost instantly. The hypothesis proposed by the authors of a three-dimensional perception of the external world by a person needs an in-depth mathematical justification. Therefore, we can assume that this is another step in solving the problem of human perception of light information.Conclusions. The electromagnetic theory of colour perception by the human visual analyser of light information has been constructed in contrast to the corpuscular. Calculations of the electrophysiological parameters of rhodopsin molecules included in the rods are presented, and, a model of resonant perception of electromagnetic oscillations for the visible range of light by the human eye has been developed on this basis. Calculations based on the developed model for converting information in the visible light range of the electromagnetic spectrum made it possible to more accurately determine the number of colour shades distinguishable by the human eye. A mathematical model describing the transmission of information about the spectrum and intensity of the electromagnetic signal of the visible range of the spectrum transformed by the eyes to the central nervous system has been proposed. The speed of information transmission along the optic nerve has been calculated. The hypothesis for the volumetric perception of external information by the visual analyzer and the central nervous system has been proposed. Practical application of the developed model can be devices allowing to restore vision, as well as devices for correcting vision function built on its basis.

Research Into Monochromatic Colour Vision Thresholds And Determination Of The Trichromatic ColourMatching Coefficients

The authors experimentally defined the dependences of chromaticity thresholds between an object and a background for 10 trichromatic observers. The experiments included observation of monochromatic objects with dimension of (2?2) angular degree against a white background. Based on the statistical theory of human threshold colour vision, it was proved that in the XYZ colorimetric system, the value of Y coordinate of the primary colour Mphys is positive and lies along the y=1x line. This fact allowed to define all the characteristics of a trichromatic physiological system (LMS)phys necessary for chromatic calculations.

Electronic Eye Based on RGB Analysis for the Identification of Tequilas.

The present work reports the development of a biologically inspired analytical system known as Electronic Eye (EE), capable of qualitatively discriminating different tequila categories. The reported system is a low-cost and portable instrumentation based on a Raspberry Pi single-board computer and an 8 Megapixel CMOS image sensor, which allow the collection of images of Silver, Aged, and Extra-aged tequila samples. Image processing is performed mimicking the trichromatic theory of color vision using an analysis of Red, Green, and Blue components (RGB) for each image’s pixel. Consequently, RGB absorbances of images were evaluated and preprocessed, employing Principal Component Analysis (PCA) to visualize data clustering. The resulting PCA scores were modeled with a Linear Discriminant Analysis (LDA) that accomplished the qualitative classification of tequilas. A Leave-One-Out Cross-Validation (LOOCV) procedure was performed to evaluate classifiers’ performance. The proposed system allowed the identification of real tequila samples achieving an overall classification rate of 90.02%, average sensitivity, and specificity of 0.90 and 0.96, respectively, while Cohen’s kappa coefficient was 0.87. In this case, the EE has demonstrated a favorable capability to correctly discriminated and classified the different tequila samples according to their categories.

Research on blur discrimination thresholds of three-Channel for color image

On the basis of modern theory of color vision, the blur discrimination threshold of color image with three channels (luminance, red-green and the yellow-blue channel) in the opponent color space (DKL space) is studied through visual experiments in this paper. The visual evaluation experiment is designed by the psychophysical method based on Quest algorithm. Finding the blur discrimination threshold of color image according to the DKL space is of great significance for helping us understand color perception of image. It also has a wide range of applications in areas such as color image compression during color image transmission. Two (flowers and artificial object) typical images in the McGill standard color image database were chosen as the experimental images. After converting the color space of the image from RGB to DKL space, Gaussian low-pass filtering is used to establish the fuzzy image database. Quest algorithm which is a psychological physical method is used to design the visual evaluation experiment. Eleven volunteers with normal color vision were invited to participate in the visual evaluation experiment for each of the three channels of the two images. Our main conclusions are: (1) Human eyes are more sensitive to luminance information than color information. (2) The larger the contrast of the image and the smaller the uniformity of the image, the more sensitive the human eye is to changes in image blur.

Fractional-Order Spatial Steganography and Blind Steganalysis for Printed Matter: Anti-Counterfeiting for Product External Packing in Internet-of-Things

This paper advocates a novel conceptual formulation of the fractional-order spatial steganography (FSS) and blind steganalysis for printed matter, which can be efficiently employed in the anti-counterfeiting for product external packing in Internet-of-Things (IoT). Traditional digital steganography is not printable. Within the limits of our knowledge, until now, there are not a well-established steganography and a corresponding steganalysis for printed matter in IoT, which should receive desired attention. Fractional calculus has potentially received prominence in applications in the domain of image processing mainly because of its strengths like long-term memory, nonlocality, and weak singularity. Therefore, in an attempt to overcome the aforementioned technical limitation of traditional digital steganography, this paper has studied here, as an interesting theoretical problem, would it be possible to apply the capability of preserving the edges and textural details of fractional calculus to the achievement of the steganography and steganalysis for printed matter in IoT. Motivated by this inspiration, in this work, this paper introduces a novel conceptual formulation of an FSS and a fractional-order blind steganalysis (FBS) for printed matter. At first, according to the opponent process theory of color vision, to better achieve the imperceptibility of the hidden secret information, this paper uses both the self-similar complex textures in a neighborhood and the opponent channel of blue versus yellow to implement FSS for printed matter. Second, without requiring a priori knowledge regarding the characteristics of the original carrier image, hidden secret image, and steganography, an FBS, a fractional-order multimodal function optimization algorithm, is proposed. Finally, the efficient capability of hiding secret information of FSS and that of detecting secret information of FBS are analyzed in detail experimentally, respectively. These two important advantages lead to the superiority of the proposed approach for defending against statistics attack, rotation and distortion attack, cropping attack, scaling attack, noise attack, and color copy attack. The main contribution of this paper is the first preliminary attempt of a feasible achievement of a spatial steganography and a blind steganalysis for printed matter.

A β-carotene-binding protein carrying a red pigment regulates body-color transition between green and black in locusts

Changes of body color have important effects for animals in adapting to variable environments. The migratory locust exhibits body color polyphenism between solitary and gregarious individuals, with the former displaying a uniform green coloration and the latter having a prominent pattern of black dorsal and brown ventral surface. However, the molecular mechanism underlying the density-dependent body color changes of conspecific locusts remain largely unknown. Here, we found that upregulation of β-carotene-binding protein promotes the accumulation of red pigment, which added to the green color palette present in solitary locusts changes it from green to black, and that downregulation of this protein led to the reverse, changing the color of gregarious locusts from black to green. Our results provide insight that color changes of locusts are dependent on variation in the red β-carotene pigment binding to βCBP. This finding of animal coloration corresponds with trichromatic theory of color vision.

Formalizations of the retinex model and its variants with variational principles and partial differential equations

Land and McCann introduced the retinex model as a computational theory of color vision. However, retinex details were described algorithmically rather than mathematically. Soon after the birth of retinex, Horn proposed a drastic simplification of the model, which, however, had the merit of being mathematically explicit and rigorous. As a consequence, at least two different interpretations of retinex appeared in the literature almost at the same time. This generated a lot of confusion about the name retinex that persists even now. The aim of this paper is to present an overview about the different interpretations and the corresponding mathematical formalizations of retinex in terms of variational principles and partial differential equations.

Polychromatic SSVEP stimuli with subtle flickering adapted to brain-display interactions

Objective. Interactive displays armed with natural user interfaces (NUIs) will likely lead the next breakthrough in consumer electronics, and brain-computer interfaces (BCIs) are often regarded as the ultimate NUI-enabling machines to respond to human emotions and mental states. Steady-state visual evoked potentials (SSVEPs) are a commonly used BCI modality due to the ease of detection and high information transfer rates. However, the presence of flickering stimuli may cause user discomfort and can even induce migraines and seizures. With the aim of designing visual stimuli that can be embedded into video images, this study developed a novel approach to induce detectable SSVEPs using a composition of red/green/blue flickering lights. Approach. Based on the opponent theory of colour vision, this study used 32 Hz/40 Hz rectangular red-green or red-blue LED light pulses with a 50% duty cycle, balanced/equal luminance and 0°/180° phase shifts as the stimulating light sources and tested their efficacy in producing SSVEP responses with high signal-to-noise ratios (SNRs) while reducing the perceived flickering sensation. Main results. The empirical results from ten healthy subjects showed that dual-colour lights flickering at 32 Hz/40 Hz with a 50% duty cycle and 180° phase shift achieved a greater than 90% detection accuracy with little or no flickering sensation. Significance. As a first step in developing an embedded SSVEP stimulus in commercial displays, this study provides a foundation for developing a combination of three primary colour flickering backlights with adjustable luminance proportions to create a subtle flickering polychromatic light that can elicit SSVEPs at the basic flickering frequency.

To What Extent Is the Zone Theory of Color Vision Substantiated

To What Extent Is the Zone Theory of Color Vision Substantiated

Parallel inputs to memory in bee colour vision.

In the 19(th) century, it was found that attraction of bees to light was controlled by light intensity irrespective of colour, and a few critical entomologists inferred that vision of bees foraging on flowers was unlike human colour vision. Therefore, quite justly, Professor Carl von Hess concluded in his book on the Comparative Physiology of Vision (1912) that bees do not distinguish colours in the way that humans enjoy. Immediately, Karl von Frisch, an assistant in the Zoology Department of the same University of Münich, set to work to show that indeed bees have colour vision like humans, thereby initiating a new research tradition, and setting off a decade of controversy that ended only at the death of Hess in 1923. Until 1939, several researchers continued the tradition of trying to untangle the mechanism of bee vision by repeatedly testing trained bees, but made little progress, partly because von Frisch and his legacy dominated the scene. The theory of trichromatic colour vision further developed after three types of receptors sensitive to green, blue, and ultraviolet (UV), were demonstrated in 1964 in the bee. Then, until the end of the century, all data was interpreted in terms of trichromatic colour space. Anomalies were nothing new, but eventually after 1996 they led to the discovery that bees have a previously unknown type of colour vision based on a monochromatic measure and distribution of blue and measures of modulation in green and blue receptor pathways. Meanwhile, in the 20(th) century, search for a suitable rationalization, and explorations of sterile culs-de-sac had filled the literature of bee colour vision, but were based on the wrong theory.

Ragona-Scinà's (1847) Method for, and Observations of, Simultaneous Color Contrast.

In 1847, Domenico Ragona-Scinà (1820–1892) published a method of optically superimposing images using an angled piece of colored glass. He showed that if one looks at a black, filled circle through the colored glass and superimposes on it the reflection from the glass of something white, the filled circle looks tinted with the complementary color of the background: simultaneous color contrast or contrast color. Although Ragona-Scinà’s method and his observation have been cited into the 21st century, the former for its simplicity and the latter for its challenges to early theories of color vision, some errors have crept in and the phenomenon still lacks an agreed-on explanation. We provide some biographical information about Ragona-Scinà, set the method and the observation into their historical and theoretical contexts, and give a translation into English of Ragona-Scinà’s Italian-language paper.

Image processing applications through a variational perceptually-based color correction related to Retinex

The retinex theory of color vision has been a light of inspiration for color researchers since its inception 50 years ago. It has been adapted to work for different goals such as shadow removal, high dynamic range imaging, or computational color constancy. Back in 2007 a variational perceptually-based color correction model related to Retinex was presented by Bertalmío and colleagues. In this paper we first comment on this model and later we review different image processing applications that have been obtained by performing small modifications to it, namely color gamut mapping and image dehazing.

How bees distinguish black from white.

Bee eyes have photoreceptors for ultraviolet, green, and blue wavelengths that are excited by reflected white but not by black. With ultraviolet reflections excluded by the apparatus, bees can learn to distinguish between black, gray, and white, but theories of color vision are clearly of no help in explaining how they succeed. Human vision sidesteps the issue by constructing black and white in the brain. Bees have quite different and accessible mechanisms. As revealed by extensive tests of trained bees, bees learned two strong signals displayed on either target. The first input was the position and a measure of the green receptor modulation at the vertical edges of a black area, which included a measure of the angular width between the edges of black. They also learned the average position and total amount of blue reflected from white areas. These two inputs were sufficient to help decide which of two targets held the reward of sugar solution, but the bees cared nothing for the black or white as colors, or the direction of contrast at black/white edges. These findings provide a small step toward understanding, modeling, and implementing in silicon the anti-intuitive visual system of the honeybee, in feeding behavior.

A model of color constancy and efficient coding can predict lightness induction

A recent variational implementation of Land's Retinex theory of color vision can improve the appearance of images without introducing artifacts (Bertalmío et al. 2009). Through anti-symmetrization of the resulting partial differential equation, this methodology emulates color constancy on both under and over exposed images. Remarkably, this formulation of Retinex is formally equivalent to local histogram equalization and has the same form as the Wilson-Cowan equations that model the response of populations of cortical neurons. The model cannot predict the phenomena of color assimilation because it can only increase the contrast of an image. However an addition to the model, designed to allow it to reach a steady state in a constant time regardless of stimulus structure, can predict assimilation. This approach weights the magnitude of each convergence step by computing the ratio of image variance and histogram uniformity. This model can predict the perception of achromatic induction from the data of Rudd (2010) investigating the perceived lightness of a disk-and-ring stimulus. In particular the model predicts when contrast switches to assimilation, and it can also predict how the slope and curvature of such functions vary with ring width and polarity. Meeting abstract presented at VSS 2014

The Discovery of Spectral Opponency in Visual Systems and its Impact on Understanding the Neurobiology of Color Vision

The two principal theories of color vision that emerged in the nineteenth century offered alternative ideas about the nature of the biological mechanisms that underlie the percepts of color. One, the Young-Helmholtz theory, proposed that the visual system contained three component mechanisms whose individual activations were linked to the perception of three principal hues; the other, the Hering theory, assumed there were three underlying mechanisms, each comprising a linked opponency that supported contrasting and mutually exclusive color percepts. These competing conceptions remained effectively untested until the middle of the twentieth century when single-unit electrophysiology emerged as a tool allowing a direct examination of links between spectral stimulation of the eye and responses of individual cells in visual systems. This approach revealed that the visual systems of animals known to have color vision contain cells that respond in a spectrally-opponent manner, firing to some wavelengths of stimulation and inhibiting to others. The discovery of spectral opponency, and the research it stimulated, changed irrevocably our understanding of the biology of color vision.

Modelling of chromatic contrast for retrieval of wallpaper images

AbstractColour remains one of the key factors in presenting an object and, consequently, has been widely applied in retrieval of images based on their visual contents. However, a colour appearance changes with the change of viewing surroundings, the phenomenon that has not been paid attention yet while performing colour‐based image retrieval. To comprehend this effect, in this article, a chromatic contrast model, CAMcc, is developed for the application of retrieval of colour intensive images, cementing the gap that most of existing colour models lack to fill by taking simultaneous colour contrast into account. Subsequently, the model is applied to the retrieval task on a collection of museum wallpapers of colour‐rich images. In comparison with current popular colour models including CIECAM02, HSI and RGB, with respect to both foreground and background colours, CAMcc appears to outperform the others with retrieved results being closer to query images. In addition, CAMcc focuses more on foreground colours, especially by maintaining the balance between both foreground and background colours, while the rest of existing models take on dominant colours that are perceived the most, usually background tones. Significantly, the contribution of the investigation lies in not only the improvement of the accuracy of colour‐based image retrieval but also the development of colour contrast model that warrants an important place in colour and computer vision theory, leading to deciphering the insight of this age‐old topic of chromatic contrast in colour science. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 361–373, 2015

The Logic of Color: Theory and Graphics in Christine Ladd-Franklin's Explanation of Color Vision

In the years after 1870, two theories of color vision vied for primacy: the “trichromatic” theory and a four-color theory, also known as an “opponent” theory of color vision. Among scientists who participated in this debate, mathematician Christine Ladd-Franklin (1847–1930) made special use of graphics as a rhetorical template for reasoning and explanation. Her later work included figures modeled upon novel graphic representations of logical relationships to describe chemical reactions fundamental to visual processes. These and other illustrations demonstrate, in retrospect, how innovation in graphic notation can underlie shifts in the practice and perception of science.