Physics
The Nature of Colour
"The Nature of Colour" refers to the physical and perceptual properties of light that give rise to the sensation of color. In physics, color is understood as the result of the interaction between light, objects, and the human visual system. This interaction involves the absorption, reflection, and transmission of light, as well as the perception of different wavelengths as distinct colors.
Written by Perlego with AI-assistance
Related key terms
1 of 5
9 Key excerpts on "The Nature of Colour"
- Rangayyan, Rangaraj M., Acha, Begoña, Serrano, Carmen(Authors)
- 2011(Publication Date)
1 The Nature and Representation of Color Images Color is an important and often pleasant part of the visual domain; however, color is not a physical quantity but a human sensation. Color is the visual perception generated in the brain in response to the incidence of light, with a particular spectral distribution of power, on the retina. The retina is com-posed of photoreceptors sensitive to the visible range of the electromagnetic (EM) spectrum [21,36–38]. In general, different spectral distributions of power produce distinct responses in the photoreceptors, and therefore, different color sensations in the brain. See Table 1.1 for a representation of the EM spectrum and its parts related to various modalities of imaging, and Figure 1.1 for a display of the visible color spectrum as a part of the EM spectrum [1,39]. The diffraction of sunlight by water shows the visible color spectrum in the form of a rainbow; see Figure 1.2 for an example. When a surface is illuminated with a source of light, it absorbs some parts of the incident energy and reflects the remaining parts. When a surface is identi-fied with a particular color, for example, red, it means that the surface reflects light energy in the particular range of the visible spectrum associated with the sensation of red and absorbs the rest of the incident energy. Therefore, the color of an object varies with the illumination. An object that reflects a part of the light that is incident upon it may be considered a secondary source of light. To reproduce and describe a color, a color representation model or color space is needed. Many color spaces have been proposed and designed so as to Figure 1.1 The visible color spectrum and approximate naming of its constituent colors.
eBook - PDF- Ronald N. Giere(Author)
- 2010(Publication Date)
- University of Chicago Press(Publisher)
Introduction Color vision provides the best exemplar I know for the kind of perspectivism that characterizes modern science. It is a phenomenon with which almost everyone is familiar. Moreover, the basic science of color vision is quite acces-sible. So one can here easily follow a naturalistic methodological stance. Of course, the phenomenon of color vision has been a staple of empiricist philosophers since Locke. It has also recently become a topic of considerable interest among contemporary analytic philosophers. 1 Nevertheless, I prefer to begin with the contemporary science of color vision. Basic Color Science Most humans experience the world as apparently containing colored objects as well as other colorful phenomena such as sunsets. The range of human color vision is familiar from the spectrum produced by rainbows. In the spectrum, the colors range from a deep purple to a dark red. It has long been known that these colors are in some way related to electromagnetic radia-tion with different wavelengths, ranging from roughly 400 to 700 nanome-ters ( 1 nm = 10 − 9 meters, that is, one-billionth of a meter). This is but a tiny fraction of the total electromagnetic spectrum, which includes cosmic rays with wavelengths around 10 − 14 meters and radio waves with wavelengths around 10 6 meters. See plate 1 in the color insert. In the nineteenth century, the German physiologist Ewald Hering showed that one aspect of our perceptual color space has a quite definite structure exhibited in what is now called a hue circle (plate 2 in the color CHAPTER TWO COLOR VISION insert). A continuous version of this circle contains all the hues perceived by humans. In addition, colors differ in saturation , or intensity, and brightness , that is, relative lightness or darkness. These three aspects of color can be represented in a three-dimensional array, such as the Munsell Solid, which represents all the colors that can be perceived by humans.
eBook - PDFFood Colorants
Chemical and Functional Properties
- Carmen Socaciu(Author)
- 2007(Publication Date)
- CRC Press(Publisher)
3 1 Physics of Color Horst A. Diehl CONTENTS 1.1 Introduction ...................................................................................................... 3 1.2 Role of Light and Color in Nature .................................................................. 4 1.3 Physical Nature of Light and Color ................................................................ 5 1.3.1 Dualism of Light as Wave or Assembly of Photons ........................... 6 1.3.2 Electromagnetic Spectrum of Light with Regard to Its Impact on Matter and Its Base for Analytical Tools ....................................... 8 1.4 Physical Detecting Devices For Light and Color .......................................... 14 1.5 Individual Perceptions of Color and Brightness and Standardization Problems ......................................................................................................... 16 References ................................................................................................................ 20 1.1 INTRODUCTION With regard to choice and consumption of food, all human sensory perceptions are involved. Among them, vision is the most important one for selecting food and appreciating its quality. Color is an intrinsic property of food. A color change of food often is caused by a quality change. Consumers are attracted by the color of a food product. This implies three main consequences for food producers: 1. Food quality should be controlled by optical inspection. 2. Food processing steps may change food color. 3. Colorants may be added to food as preservatives or simply to attract consumers. Intrinsic food colorants can be conserved more or less during food processing. The pigments that color the original living biological material often possess essential functional properties like anti-oxidative effects, radical scavengers or are transmitters of signals or energy.
- Derek H. Brown, Fiona Macpherson, Derek H. Brown, Fiona Macpherson(Authors)
- 2020(Publication Date)
- Routledge(Publisher)
The task of Section 2 will be to examine the links between the history of science and the problem of colour and the secondary qualities more generally. I present criticisms of the standard narrative which dates the origin of the problem of colour to sometime in the seventeenth century. In Section 3 I will discuss Mark Wilson’s critical re-evaluation of the primary-secondary distinction, which is itself informed by a complex view of scientific concepts and the way that they attach themselves to natural phenomena. 53 Mazviita Chirimuuta Section 4 moves towards the epistemology of science, and Ron Giere’s influential theory of scientific perspectivism. In his presentation of perspectivism, Giere presents colour vision as the guiding metaphor for how different scientific models and theories offer us a patchwork set of varied views on the world. Finally, in Section 5 we consider the position of colour ontology, as currently practised, within the broader currents of naturalized metaphysics. 2 Philosophy of colour and the history of science A widely held view is that we should take the philosophical problem of colour seriously because it gets to the heart of the metaphysical commitments of modern science as it emerged in the seventeenth century. Alfred North Whitehead was one philosopher who framed the problem in this way: But whatever theory [of light] you choose [i.e. wave or corpuscular], there is no light or colour as a fact in external nature. There is merely motion of material. Again, when the light enters your eyes and falls on the retina, there is merely motion of material. Then your nerves are affected and your brain is affected, and again this is merely motion of material. (Whitehead, 1938, 69) Whitehead continues: But the mind in apprehending also experiences sensations which, properly speaking, are qualities of the mind alone.
eBook - PDF- Wilhelm Kettler, Manfred Binder, Walter Franz, Peter Gabel, Stephan Gauss, Uwe Hempelmann, Rainer Henning, Hans-Jörg Kremitzl, Sandra Weixel, Gerhard Wilker(Authors)
- 2016(Publication Date)
- Vincentz Network(Publisher)
The raw colour signals themselves do not penetrate into our consciousness. Colour vision incorporates the concept of colour constancy. Our visual interpretation of a hue always takes ambient lightness into account. For example, the illumination level outdoors in direct sunlight is several orders of magnitude greater than it is inside. The stimuli reach-ing our eyes outdoors should lead to white-out of any object, which would only appear white. The combined input from the eyes and the brain leads to a recognition that the different stimulus triggered by a green apple, say, stems from a change in lighting conditions and not from a change in the hue of the apple itself. Colour constancy is therefore based on the notion that the lightness of an object is determined by the lightness of the environment or of a reference object, and our colour perception changes accordingly (“related colours”, see also Section I.1). For a good example, consider our visual perception of the moon. If we look at it in the afternoon, it appears pale yellow against the blue of the sky. Some hours later, in the dark, we perceive it as being bright yellow even though its lightness, which is the result of illumination by the sun, has not changed much during this short time. A further special effect is that we can make out the details of the moon’s surface at night. 1 The basic idea behind this concept was published in 1807 by Thomas Young I Fundamentals of colour perception 22 2 Light as Electromagnetic Radiation The light perceived by the human eye consists of electromagnetic radiation. Figure I.7 shows the different wavelength and frequency ranges of electromagnetic radiation on a logarithmic scale, along with several applications in these ranges. The human eye can only detect radiation in the tiny wavelength range of 370 to 700 nm (1 nm = 10 -9 m). Due to the low sensitivity of our eyes outside this range, colour measurements are made over the range 400 to 700 nm by international agreement.
eBook - PDFArt in Chemistry
Chemistry in Art
- Barbara R. Greenberg, Dianne Patterson(Authors)
- 2007(Publication Date)
- Libraries Unlimited(Publisher)
4. Discuss the subject of your picture. What is the chemistry significance of your subject matter? LIGHT AS A SOURCE OF COLOR: THE ELECTROMAGNETIC SPECTRUM How are light and color related? • Visible white light is a source of color. The color observed for an object is a function of the light source and the reflective and absorbing properties of the surface that the light strikes. • If white light strikes a red apple, because white light contains all of the visible colors—red, orange, yellow, green, blue, indigo, and violet, all of the visible colors will be absorbed except for red, which will be reflected. Thus, the apple is red. Color begins with and is derived from light, either natural or artificial. Where there is little light, there is little color; where the light is strong, the color is likely to be particularly intense. We notice at such times as dusk or dawn, when the light is weak, that it is difficult Light as a Source of Color: The Electromagnetic Spectrum / 9 to distinguish one color from another. Under bright, strong sunlight, such as in tropical climates, colors have more intensity. Where does all light come from? • Initially, all light comes to us from the sun. • Certain atoms and molecules store light energy and emit that light energy under certain conditions, such as during a chemical change. Burning is a common example of such a chemical change. • Light from atoms also appears when excited atoms release energy. What is electromagnetic radiation? • A form of energy that travels in waves is called electromagnetic radiation. • The following relationship exists between the wave frequency, n, and wavelength, l: frequency times wavelength = velocity. Velocity refers to the speed of electromagnetic radiation waves in a vacuum. It is a constant (2.998 x 10 8 m/s), sometimes called the speed of light, c.
eBook - PDFColor Theory for the Make-up Artist
Understanding Color and Light for Beauty and Special Effects
- Katie Middleton(Author)
- 2022(Publication Date)
- Routledge(Publisher)
CHAPTER 1 Color Theory 2 Color Theory WHY WE SEE COLOR It’s easy to take color for granted, because today we have access to any color imaginable. We can quickly select and mix millions of color combinations using paint, dye, or even digital color on a screen. Even though we are equipped with color vision without having to think about it, it’s important to take time to understand color, because it’s one of the most important tools we have as artists. The Visible Spectrum “All colours will agree in the dark” francis bacon The Essays or Counsels Civil and Moral, 1597 1.1 Sir Isaac Newton (1642–1727) examining light with a prism In the late 1600s, Sir Isaac Newton discovered that white light could be broken down into all of the colors of the rainbow, which make up the visible spectrum that we know today. Through his experiments of passing white light though a prism, he found that the light refracts and separates into red, orange, yellow, green, blue, indigo, and violet. This made it apparent that white is not a separate color of light, but instead is the result of all color frequencies being reflected at one time. The existence of light is the reason we are able to see color at all, which explains why everything appears black when the lights are turned of. 1.2 Prism separating light The spectrum that we see is a type of electromagnetic radiation, and each colored wavelength has its own frequency. The human eye is sensitive to these wavelengths and the brain is able to identify them as colors. Red has the longest wavelength and the lowest frequency, while violet has the shortest wavelength and highest frequency. Some animals and insects (like bees) can see beyond the human’s visible spectrum and can observe other frequencies, like ultraviolet light. Every object that we see has its own molecular structure, which absorbs or reflects the wavelengths that we perceive as colors.
eBook - PDFColour and the Optical Properties of Materials
An Exploration of the Relationship Between Light, the Optical Properties of Materials and Colour
- Richard J. D. Tilley(Author)
- 2010(Publication Date)
- Wiley(Publisher)
(a) The colours of the spectrum are arranged around a curved line and nonspectral colours fall on the line joining violet (400 nm) and red (700 nm). The figures marked around the outer edge of the curve denote the wavelength of the colour. Points within the area of the diagram represent colours formed by the additive mixing of light and can be specified by the appropriate x-and y-values. The point W represents white light. (b) A straight line through W links two complementary colours on the periphery of the diagram, in this example red and cyan. (c) The lever rule gives the proportions of complementary colours which are needed to create white light. In this example, the amount of red light is given by r/(r þ c) and the amount of cyan light by c/(r þ c) Colour and the Optical Properties of Materials 32 1.13 The Interaction of Light with a Material Colour is inherent in the light that leaves an emitting source; but most often before it reaches the eye it interacts with matter of many types: gases, liquids and solids. The colour observed is thus a function of both the source radiation and the interactions that have occurred. The way that light interacts with a material can be described in terms of scattering or absorption. To a first approximation, scattering is well treated by assuming that the light behaves as an electromagnetic wave, while absorption is best treated in terms of photons. If the energy of the scattered wave/photon is the same as that of the incident wave/photon then the scattering is called elastic scattering, and otherwise inelastic scattering. For historical reasons, the term scattering itself, especially elastic scattering, is usually reserved for the interaction of light with randomly distributed small particles. Elastic scattering from a surface is normally called reflection , and elastic scattering into a transparent solid is called refraction .
eBook - PDFSchopenhauer: Parerga and Paralipomena: Volume 2
Short Philosophical Essays
- Arthur Schopenhauer, Christopher Janaway, Adrian Del Caro(Authors)
- 2015(Publication Date)
- Cambridge University Press(Publisher)
This can be decided by observing the a qualitas occulta (colorifica) b mit der Empfindung derselben c Handbuch der Augenheilkunde [1830] On colour theory 165 colour right next to the grey through a prism in order to see which of the two 195 relates by refraction as brightness to dimness: if they are alike in this, then the refraction must not yield any colour phenomenon. Our test of the purity of a given colour, e.g. whether this yellow is exactly so or whether it tends towards green or even towards orange, is based on the strict accuracy of the fraction through which it is expressed. However, that we can judge this arithmetic ratio through mere feeling is confirmed by music, where the harmony is based on many greater, more complicated numerical ratios of simultaneous vibration whose tones can be judged upon mere hearing with the greatest precision and yet arithmetically. – Just as it is possible to distinguish the seven tones of the scale from the innumerable others that lie between them only by the rationality of their frequencies, so in the same way it is possible to distinguish the six colours given unique names from the innumerable colours lying between them only by the rationality and simplicity of the fractions of the activity of the retina they represent. Just as when playing an instrument I test the accuracy of a tone by hitting its fifth or octave, so I test the purity of a perceived colour by evoking its physiological spectrum, a the colour of which is frequently easier to judge than the colour itself; thus have I noticed, e.g., that the green of a grass tends starkly to yellow only by seeing that the red of its spectrum tends starkly towards violet. §104 After Buffon had discovered the phenomenon of physiological colours on which my entire theory is based, it was explained using Newton’s theory by Father Scherffer in his Treatise on Accidental Colours, b Vienna, 1765.
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
