Nearly 40 years ago, in his book “Human Color Vision,” Boynton wrote “The chromatic code of the visual nervous system is incomplete and difficult to interpret;” however, a series of recent discoveries are providing the missing puzzle pieces needed to complete a picture of the diversity of ganglion cell types involved in primate color vision and their varied functions. Boynton proposed a model that, in its simplest form, has just two color channels, red-green (RG) comparing L vs. M cones and blue-yellow (BY) comparing S-cones to the other two types. Neurobiological explanations of color vision have focused on the two ganglion cell types that most closely correspond to the channels Boynton described, small bistratified for BY and midget ganglion cells with L vs. M opponency for RG. However, in contrast to this simple idea, recent evidence suggests that there are many ganglion cell types and subtypes in the primate retina that carry color information. These have appeared at vastly different times over the history of the evolution of vertebrates, they project to several different places in the brain and serve a variety purposes. Many appeared before mammals evolved; including color coded ganglion cells involved in the modulation of sleep and mood, guidance of movements, detection and object segmentation. In contrast, based on recent results we suggest that four specific types of chromatically coded ganglion cells evolved exclusively in primates for the uniquely anthropoid function of assigning blue, yellow, red and green colors to objects for use in identification and classification.

---

---

Ausgehend von einer Begriffsklärung des Wortes Pigment werden die verschiedenen Pigmentklassen erarbeitet. Die anorganischen Pigmente werden in der Unterteilung natürliche Erden, natürliche Mineralien, synthetische anorganische Pigmente und Gläser in ihren charakteristischen Vertretern vorgestellt. Die organischen Pigmente werden als natürliche und als synthetische organische Pigmente vorgestellt, sowie einige Beispiele von Pigmenten, welche in ihren Eigenschaften verschiedenen Gruppen gleichzeitig angehören.
Besondere Eigenschaften der Oberfläche, der chemischen Stabilität und der Lichtechtheit werden bei geeigneten Vertretern angesprochen. Unter anderem wird Dr. Georg Kremer über Ocker, Purpur, Indigo, Krappwurzeln und Smalte sprechen.

---

---

“All perception is illusion” has some grain of truth, but is not very conducive to understanding. However, in the case of colour, “out there” are only spectra of incident light, absorbance and reflectance. Very little of this rich information remains after passing through our three cone types. Yet our perceptual apparatus creates out of this stable categories, which we call colours, which can be consistently communicated and reflect stable object properties even under widely varying illumination (colour constancy). The wide variability of colour naming across cultures indicates that there is more to colour than just physiology. And indeed the poetry of colour can deeply touch our innermost. My talk will will not be at the cutting edge of science but rather introduce a little to our understanding of colour vision, demonstrate that we are all –somewhat– colour blind, and pursue many beautiful factors that affect our perception of colour.

“Alles war wir wahrnehmen ist eine Täuschung” – da ist was dran, aber es hilft nicht viel wenn wir unsere Wahrnehmung besser verstehen wollen. Bei Farbe ist aber die “innere Konstruktion” besonders deutlich: “Da draußen” sind nur Spektren von Beleuchtung, Absorption und Reflektion; davon bleibt nur wenig Information übrig, wenn das Licht unsere 3 Zapfentypen aktiviert hat. Und doch schafft es unser Wahrnehmungsapparat, daraus Kategorien, eben die Farben, zu konstruieren und zu kommunizieren, die Objekteigenschaften stabil repräsentieren auch unter stark variierender Beleuchtungsspektren (Farbkonstanz). Die große Varianz der Farbkategorien über Weltkulturen hinweg verdeutlicht, dass zu Farbe mehr gehört als reine Physiologie; auch kann uns die Poesie der Farben besonders tief berühren. Mein Vortrag wird nicht neueste wissenschaftliche Erkenntnisse vermitteln, sondern etwas in das Verständnis des Farbensehens einführen, demonstrieren, dass wir alle in gewissem Maße farbenblind sind, und mannigfache und schöne Einflussfaktoren auf unsere Farbwahrnehmung vorführen.

---

---

The question of color categorization has long been caught in the crossfire between universality and cultural relativism. Color categories across languages are somewhat consistent, suggesting a common basis in physiology. But the variability between languages, and the lack of physiological or other causal evidence, promote the alternative idea that languages are constitutive of color categories. I will attempt to reconcile these positions through an analysis of a new, extensive, well-controlled dataset on color-naming in three diverse groups: the Tsimane’, a hunter-gatherer isolate in the Amazon; Bolivian Spanish speakers; and English speakers near Boston. These data resolve widespread methodological concerns about the World Color Survey (WCS), and license an analysis of this impressive dataset covering 110 languages to determine how successfully people can communicate color. Despite a large range of average communicative efficiency across languages, we discovered remarkable within-language consistency: in all languages communication was best for warm colors (yellows/reds), rather than cool colors (blues/greens). We show that the communicative efficiency of a given color is predicted by the frequency with which salient objects have that color—in natural images, we found that objects tend to be warm-colored against cool-colored backgrounds; this relationship was true for natural objects as well as artificially colored objects. These results suggest that the color terms across languages are driven by the common goal to optimize communication about colors of likely relevance. In additional experiments, in Tsimane’, Bolivian Spanish, and English, we assessed memory color for familiar objects and labeling of real-world objects. The results support the idea that the overall communicative efficiency of a language is determined by the extent to which color is generally useful for the culture. Together, the results provide the first explanation of the most basic, universal color categorization, and show how this single mechanism—usefulness—can also account for the variance among color-naming systems.

---

---

Department of Psychology, Durham University Institute of Behavioural Sciences, University of Helsinki Humans perceive the colors of objects in a relatively stable manner regardless of widely varying viewing conditions – an ability called color constancy. According to a common suggestion emanating from a Bayesian theory of vision, the visual system uses constraints from prior knowledge to infer object properties from noisy sensory inputs.
However, very little is known about how this knowledge is learned from the visual input, and how it is used in visual estimation tasks. I will talk about how object knowledge is learned from visual input for color, how it is used by human observers in noisy color estimation tasks, and how it interacts with well-known color context effects. I will present a quantitative framework in which learning, memory, and perception can be considered jointly, reflecting the structure of natural tasks. I will argue that to understand color perception in the real world, all of these processes need to be considered together.

---

---

---

---