BMG 103 Color Theory PDF - 2017

Yashwantrao Chavan Maharashtra Open University Digital Art B. Sc. in Media Graphics and Animation BMG 103: Color Theory YASHWANTRAO CHAVAN MAHARASHTRA OPEN UNIVERSITY T97:B.Sc. in Media Graphics and Animation [B.Sc. (MGA)] 2010 Pattern: Course code: BMG103 COLOUR THEORY YASHWANTRAO CHAVAN MAHARASHTRA OPEN UNIVERSITY Dnyangangotri, Near Gangapur Dam, Nashik 422 222, Maharshtra YASHWANTRAO CHAVAN MAHARASHTRA OPEN UNIVERSITY Vice-Chancellor : Prof. (Dr.) E. Vayunandan School of Continuing Education School Council Dr Rajendra Vadnere, Dr Surya Gunjal Smt Jyoti Shetty. Principal Chairman, Director Professor S.P. More College, Panwel School of Continuing Education School of Agriculture Science YCMOU, Nashik YCMOU, Nashik Dr Abhay Patil Assistant Professor Dr Jaydeep Naikam Dr Pranod Khandare School of Health Science Professor Assistant Professor School of Continuing Education School of Computer Science YCMOU, Nashik Shri Asvin Sonone, YCMOU, Nashik YCMOU, Nashik Associate Professor Dr Rucha Gujar Dr Latika Ajbani Assistant Professor Assistant Professor FTII Pune Shri P V Patil School of Continuing Education School of Commerce & Mgt Dy District Voc Education & YCMOU, Nashik YCMOU, Nashik Shri Ram Thakar Dr Sunanda More Training Officer, DVET, Nashik Assistant Professor Assistant Professor Shri Shankar Goenka School of Continuing Education School of Science & Tech. YCMOU, Nashik YCMOU, Nashik Country Head Wow Fafctors Ind Pvt Ltd, Delhi Author Content Editor Instrctional Technology Editor and Coordinator (Dev.) Darshana Gosavi Ravi H Tikate Dr Rajendra Vadnere MCE Society's Colege of Visual H.O.D. (Animation) Director Effect Design and Arts MCE Society's Colege of Visual School of Continuing Education Effect Design and Arts Y.C.M.O. U. Pune Pune Nashik Production Shri. Anand Yadav Manager, Print Production Centre, YCMOU, Nashik © 2017, Yashwantrao Chavan Maharashtra Open Univesity, Nashik  First Publication : June 2017  Publication No. :  Typesetting :  Printer :  Published by : Dr. Dinesh Bhonde, Registrar, Y. C. M. Open University, Nashik - 422 222. B-16-17-93 (BTH331) BMG 103: Colour Theory Credit 1 UNIT 1 COLOUR THEORY: OVERVIEW Credit 2 UNIT 2 COLOUR BASICS Credit 3 UNIT 3 COLOUR HARMONY UNIT 4 COLOUR MEANINGS Credit 4 UNIT 5 COLOUR MODEL UNIT 6 PSYCHOLOGY OF COLOUR Contents UNIT 1: COLOUR THEORY: OVERVIEW 8 1.0 INTRODUCTION 8 1.1 UNIT OBJECTIVES 9 1.2 COLOUR BALANCE AND CHROMATIC COLOURS 9 1.3 COLOUR SCHEME 10 1.4 TRADITIONAL COLOUR THEORY 13 1.4.1 Warm and cool colours 14 1.4.2 Achromatic colors 14 1.4.3 Complementary colors 15 1.4.4 Tints and shades 15 1.4.5 Split Primary Colours 16 1.5 Historical background 17 1.6 COLOUR HARMONY AND COLOUR MEANINGS 19 1.7 EMOTIONAL RESPONSE TO COLOURS 21 1.8 PHYSIOLOGICAL PRINCIPLE FOR EFFECTIVE USE OF COLOUR 24 1.8.1 Mechanism of dichromatic color vision 25 1.8.2 Human Visual System 26 1.8.3 Phototransduction 27 1.8.5 Difference between Rods and Cones 27 1.8.6 Function 28 1.8.7 Signaling 29 1.8.8 Ganglion cell 29 1.9 Lens 30 1.9.1 Position, size, and shape 31 BMG 103: Color Theory Page 1 1.9.2 Lens Structure and Function 31 1.9.3 Accommodation: changing the power of the lens 32 1.9.4 Crystallins and Transparency 32 1.10 Retina 33 1.11 Human Brain 36 1.12 Effective use of colours 37 1.14 SUMMARY 38 1.15 END QUESTIONS 39 UNIT 2: COLOUR BASICS 41 2.0 INTRODUCTION 41 2.1 UNIT OBJECTIVES 41 2.2 COLOUR SYSTEMS 41 2.3 WORKING WITH COLOUR SYSTEMS 45 2.3.1 Subtractive colour scheme 45 2.3.2 Additive colour scheme 46 2.3.3 Working with systems 47 2.4 COLOUR WHEEL 47 2.4.1 COLOR RELATIONSHIPS 48 2.4.2 Color wheels and paint color mixing 48 2.4.3 Color wheel software 49 2.4.4 Colour Scheme 49 2.5 COLOUR RELATIONSHIP 52 2.5.1 Complementary Colours 53 2.5.2 Perceptual Opposites 56 2.5.3 Color Combinations 56 2.6 COLOUR CONTRAST 56 BMG 103: Color Theory Page 2 2.7 ITTEN'S COLOUR CONTRAST 59 2.8 PROPORTION AND INTENSITY 62 2.9 CONTRAST AND DOMINANCE 64 2.10 COLOUR SHADES AND TINTS 66 2.11 COLOUR STUDIES OF COMPLEMENTARY RELATIONSHIPS 67 2.12 SUMMARY 72 2.13 KEY TERMS 72 2.14 END QUESTIONS 73 UNIT 3: COLOUR HARMONY 74 3.0 INTRODUCTION 74 3.1 UNIT OBJECTIVES 74 3.2 SOME FORMULAS FOR COLOUR HARMONY 74 3.2.2 Colour Scheme Based on Analogous Colours 74 3.2.3 Colour scheme based on complementary colour 75 3.2.4 Colour Scheme Based on Nature 75 3.3 COLOUR CONTEXT 76 3.4 Different readings of the same colour 76 3.5 classic colour schemes 77 3.5.1 Monochromatic colors 77 3.5.2 Complementary colors 78 3.5.3 Split-Complementary 78 3.5.4 Triadic colors 78 3.5.5 Tetradic colors 79 Rectangle 79 Square 79 3.6 summary 79 BMG 103: Color Theory Page 3 3.7 KEY TERMS 80 3.8 END QUESTIONS 80 UNIT 4: COLOUR MEANINGS 81 4.0 INTRODUCTION 81 4.1 UNIT OBJECTIVES 81 4.2 colour meanings and colours that go together 81 4.3 cool colours 86 4.4 warm colours the colours of excitement 86 4.5 mixed warm and cool colour scheme 87 4.6 neutral colours 87 4.7 more about colours 88 4.8 summary 92 4.9 KEY TERMS 93 4.10 END QUESTIONS 93 UNIT 5 COLOUR MODEL 94 5.0 INTRODUCTION 94 5.1 UNIT OBJECTIVES 94 5.2 OVERVIEW OF COLOUR MODEL 94 5.2.1 Tristimulus color space 94 5.2.2 CIE XYZ color space 95 5.2.3 RGB color model 97 5.2.4 HSV and HSL representations 97 5.2.5 CMYK color model 99 5.2.6 Color systems 100 5.2.7 Other uses of "color model" 101 BMG 103: Color Theory Page 4 5.2.7 Vertebrate evolution of color vision 101 5.3 LIGHT 101 5.3.1 Electromagnetic spectrum and visible light 102 5.3.2 Speed of light 103 5.3.3 Light sources 104 5.3.4 Units and measures 105 5.3.5 Historical theories about light, in chronological order 106 5.4 CIE CHROMATICITY DIAGRAM(CIE 1931 color space) 112 5.4.1 Tristimulus values 113 5.4.2 Meaning of X, Y and Z 114 5.4.3 CIE standard observer 115 5.4.4 Computing XYZ From Spectral Data 116 5.4.5 CIE xy chromaticity diagram and the CIE xyY color space 116 5.4.6 Definition of the CIE XYZ color space 119 5.5 RGB color model 125 5.6 CMYK Model 133 5.6.1 Halftoning 135 5.6.2 Benefits of using black ink 136 5.6.3 Other printer color models 139 5.6.5 Conversion 140 5.7 Hue 142 5.7.1 Computing hue 142 5.7.2 Hue vs. dominant wavelength 144 5.7.3 Hue difference: 145 5.7.4 Names and other notations for hues 145 5.8 Saturation 145 BMG 103: Color Theory Page 5 5.9 Value Color Model 147 5.10 Intuitive Color Concept 156 5.11 SUMMARY 159 5.12 KEY TERMS 160 5.13 END QUESTIONS 161 5.14 REFERENCES 162 UNIT 6 PSYCHOLOGY OF COLOUR 163 6.0 INTRODUCTION 163 6.1 UNIT OBJECTIVES 163 6.2 COLOUR PSYCHOLOGY: AN OVERVIEW 163 6.2.1 Influence of color on perception 164 6.2.2 Color preference and associations between color and mood 164 6.2.3 General model 165 6.2.4 Specific color meaning 167 6.2.5 Individual differences 170 6.2.6 Color and sports performance 172 6.2.7 Color and time perception 173 6.3 UTILIZING PSYCHOLOGICAL EFFECTS IN PAINTING 174 6.4 HOW TO JUDGE YOUR COLOUR SELECTION 182 6.5 CHARACTERISTIC COLOUR COMBINATIONS 182 6.6 COLOURS IN PHOTOGRAPHY VERSUS COLOURS IN PAINTING 183 6.7 COLOURS IN PAINTING VERSUS COLOURS IN A ROOM 184 6.8 SUMMARY 185 6.9 KEY TERMS 185 6.10 END QUESTIONS 186 6.11 REFERENCES 186 BMG 103: Color Theory Page 6 BMG 103: Color Theory Page 7 UNIT 1: COLOUR THEORY: OVERVIEW 1.0 INTRODUCTION The foundations of pre-20th-century color theory were built around "pure" or ideal colors, characterized by sensory experiences rather than attributes of the physical world. This has led to a number of inaccuracies in traditional color theory principles that are not always remedied in modern formulations. The most important problem has been a confusion between the behavior of light mixtures, called additive color, and the behavior of paint, ink, dye, or pigment mixtures, called subtractive color. This problem arises because the absorption of light by material substances follows different rules from the perception of light by the eye. A second problem has been the failure to describe the very important effects of strong luminance (lightness) contrasts in the appearance of colors reflected from a surface (such as paints or inks) as opposed to colors of light; "colors" such as browns or ochres cannot appear in mixtures of light. Thus, a strong lightness contrast between a mid-valued yellow paint and a surrounding bright white makes the yellow appear to be green or brown, while a strong brightness contrast between a rainbow and the surrounding sky makes the yellow in a rainbow appear to be a fainter yellow, or white. A third problem has been the tendency to describe color effects holistically or categorically, for example as a contrast between "yellow" and "blue" conceived as generic colors, when most color effects are due to contrasts on three relative attributes that define all colors: lightness (light vs. dark, or white vs. black), saturation (intense vs. dull), and hue (e.g. red, orange, yellow, green, blue or purple). Thus, the visual impact of "yellow" vs. "blue" hues in visual design depends on the relative lightness and saturation of the hues. These confusions are partly historical, and arose in scientific uncertainty about color perception that was not resolved until the late 19th century, when the artistic notions were already entrenched. However, they also arise from the attempt to describe the highly contextual and flexible behavior of color perception in terms of abstract color sensations that can be generated equivalently by any visual media. Many historical "color theorists" have assumed that three "pure" primary colors can mix all possible colors, and that any failure of specific paints or inks to match this ideal performance is due to the impurity or imperfection of the colorants. In reality, only imaginary "primary colors" used in colorimetry can "mix" or quantify all visible (perceptually possible) colors; but to do this, these imaginary primaries are defined as lying outside the range of visible colors; i.e., they cannot be seen. Any three real "primary" colors of light, paint or ink can mix only a limited range of colors, called a BMG 103: Color Theory Page 8 gamut, which is always smaller (contains fewer colors) than the full range of colors humans can perceive. Understanding of color theory is extremely important for you as a student and as a professional in media, graphics and animation. Which color to choose for a graphic, animation or photograph is of crucial importance. You will decide on the basis of the demand of the project, which color schemes to chose. The topics covered under this course will help you understand various concepts covered in all other courses like photoshop, illustrator, 3Ds max or Maya animation courses which you will study as part of your study in BSc(MGA). 1.1 UNIT OBJECTIVES After going through this unit, you will be able to: Elaborate colour balance and chromatic colours Explain the different colour schemes Explain the traditional colour theory Explain the effects of colours on retina, lens and brain 1.2 COLOUR BALANCE AND CHROMATIC COLOURS In photography and image processing, color balance is the global adjustment of the intensities of the colors (typically red, green, and blue primary colors). An important goal of this adjustment is to render specific colors – particularly neutral colors – correctly. Hence, the general method is sometimes called gray balance, neutral balance, or white balance. Color balance changes the overall mixture of colors in an image and is used for color correction. Generalized versions of color balance are used to correct colors other than neutrals or to deliberately change them for effect. Image data acquired by sensors – either film or electronic image sensors – must be transformed from the acquired values to new values that are appropriate for color reproduction or display. Several aspects of the acquisition and display process make such color correction essential – including the fact that the acquisition sensors do not match the sensors in the human eye, that the properties of the display medium must be accounted for, and that the ambient viewing conditions of the acquisition differ from the display viewing conditions. The color balance operations in popular image editing applications usually operate directly on the red, green, and blue channel pixel values, without respect to any color sensing or reproduction model. In film photography, color balance is typically achieved by using color correction filters over the lights or on the camera lens. Color balancing an image affects not only the neutrals, but other colors as well. An image that is not color balanced is said to have a color cast, as everything in the image appears to BMG 103: Color Theory Page 9 have been shifted towards one color. Color balancing may be thought in terms of removing this color cast. Color balance is also related to color constancy. Algorithms and techniques used to attain color constancy are frequently used for color balancing, as well. Color constancy is, in turn, related to chromatic adaptation. Conceptually, color balancing consists of two steps: first, determining the illuminant under which an image was captured; and second, scaling the components (e.g., R, G, and B) of the image or otherwise transforming the components so they conform to the viewing illuminant. Viggiano found that white balancing in the camera's native RGB color model tended to produce less color inconstancy (i.e., less distortion of the colors) than in monitor RGB for over 4000 hypothetical sets of camera sensitivities. This difference typically amounted to a factor of more than two in favor of camera RGB. This means that it is advantageous to get color balance right at the time an image is captured, rather than edit later on a monitor. If one must color balance later, balancing the raw image data will tend to produce less distortion of chromatic colors than balancing in monitor RGB. CHECK YOUR PROGRESS Explain the concept of Color Balancing. Elaborate the importance of Color Balancing. 1.3 COLOUR SCHEME In color theory, a color scheme is the choice of colors used in design for a range of media. For example, the "Achromatic" use of a white background with black text is an example of a basic and commonly default color scheme in web design. Color schemes are used to create style and appeal. Colors that create an aesthetic feeling when used together will commonly accompany each other in color schemes. A basic color scheme will use two colors that look appealing together. More advanced color schemes involve several related colors in "Analogous" combination, for example, text with such colors as red, yellow, and orange arranged together on a black background in a magazine article. The addition of light blue creates an "Accented Analogous" color scheme. Color schemes can contain different "Monochromatic" shades of a single color; for example, a color scheme that mixes different shades of green, ranging from very light (white), to very neutral (gray), to very dark (black). Use of the phrase color scheme may also BMG 103: Color Theory Page 10 and commonly does refer to choice and use of colors used outside typical aesthetic media and context, although may still be used for purely aesthetic effect as well as for purely practical reasons. This most typically refers to color patterns and designs as seen on vehicles, particularly those used in the military when concerning color patterns and designs used for identification of friend or foe, identification of specific military units, or as camouflage. A color scheme in marketing is referred to as a trade dress and can be sometimes be copyrighted, as is the pink color of Owens-Corning fiberglass. Monochromatic colors are all the colors (tints, tones, and shades) of a single hue. Monochromatic color schemes are derived from a single base hue, and extended using its shades, tones and tints (that is, a hue modified by the addition of black, gray (black + white) and white. As a result, the energy is more subtle and peaceful due to a lack of contrast of hue. Complementary color scheme Colors that are opposite each other on the color wheel are considered to be complementary colors (example: red and green). The high contrast of complementary colors creates a vibrant look especially when used at full saturation. This color scheme must be managed well so it is not jarring. Complementary color schemes are tricky to use in large doses, but work well when you want something to stand out. Complementary colors are really bad for text. Analogous color scheme Analogous color schemes use colors that are next to each other on the color wheel. They usually match well and create serene and comfortable designs. Analogous color schemes are often found in nature and are harmonious and pleasing to the eye. Make sure you have enough contrast when choosing an analogous color scheme. Choose one color to dominate, a second to support. The third color is used (along with black, white or gray) as an accent. BMG 103: Color Theory Page 11 Triadic color scheme A triadic color scheme uses colors that are evenly spaced around the color wheel. Triadic color schemes tend to be quite vibrant, even if you use pale or unsaturated versions of your hues. To use a triadic harmony successfully, the colors should be carefully balanced - let one color dominate and use the two others for accent. Split-Complementary color scheme The split-complementary color scheme is a variation of the complementary color scheme. In addition to the base color, it uses the two colors adjacent to its complement. This color scheme has the same strong visual contrast as the complementary color scheme, but has less tension. The split-complimentary color scheme is often a good choice for beginners, because it is difficult to mess up. Rectangle (tetradic) color scheme The rectangle or tetradic color scheme uses four colors arranged into two complementary pairs. This rich color scheme offers plenty of possibilities for variation. Tetradic color schemes works best if you let one color be dominant. You should also pay attention to the balance between warm and cool colors in your design. The following are some examples of media where colour schemes are used : Graphic design Product packaging Logo designing BMG 103: Color Theory Page 12 Advertising Graphical user interface Window managers such as GNOME, KDE and Blackbox Irix 4dwm's GUI uses more colour schemes, where information is stored in files named base colour palette The world wide web Cascading style sheet allow easily-editable colour scheme that may be applied to HTML webpage Publishing- The utilization of a range of colours in text and imagery of a magazine tends not to adapt to a special set of colours all around the magazine Interior designing Video games Art CHECK YOUR PROGRESS Explain the concept of Color Scheme. Elaborate the importance of Color Scheme. Explain the idea of Complementary color scheme. Explain the idea of Complementary color scheme. Explain the idea of Analogous color scheme. Explain the idea of Triadic color scheme. Explain the idea of Split-Complementary color scheme. Explain the idea of Rectangle (tetradic) color scheme. List the various areas where designers give importance to color schemes. 1.4 TRADITIONAL COLOUR THEORY For the mixing of colored light, Isaac Newton's color wheel is often used to describe complementary colors, which are colors which cancel each other's hue to produce an achromatic (white, gray or black) light mixture. Newton offered as a conjecture that colors exactly opposite one another on the hue circle cancel out each other's hue; this concept was demonstrated more thoroughly in the 19th century. BMG 103: Color Theory Page 13 A key assumption in Newton's hue circle was that the "fiery" or maximum saturated hues are located on the outer circumference of the circle, while achromatic white is at the center. Then the saturation of the mixture of two sp spectral ectral hues was predicted by the straight line between them; the mixture of three colors was predicted by the "center of gravity" or centroid of three triangle points, and so on. Primary, secondary, and tertiary colors of the RYB color model According to traditional raditional color theory based on subtractive primary colors and the RYB color model, which is derived from paint mixtures, yellow mixed with violet, orange mixed with blue, or red mixed with green produces an equivalent gray and are the painter's complementary tary colors. These contrasts form the basis of Chevreul's law of color contrast: colors that appear together will be altered as if mixed with the complementary color of the other color. Thus, a piece of yellow fabric placed on a blue background will appear tinted orange, because orange is the complementary color to blue. 1.4.1 Warm and cool colours The distinction between "warm" and "cool" colors has been important since at least the late 18th century. The contrast, as traced by etymologies in the Oxford English English Dictionary, seems related to the observed contrast in landscape light, between the "warm" colors associated with daylight or sunset, and the "cool" colors associated with a gray or overcast day. Warm colors are often said to be hues from red through yellow, browns and tans included; cool colors are often said to be the hues from blue green through blue violet, most grays included. There is historical disagreement about the colors that anchor the polarity, but 19th-century century sources put the peak contras contrastt between red orange and greenish blue. Color theory has described perceptual and psychological effects to this contrast. Warm colors are said to advance or appear more active in a painting, while cool colors tend to recede; used in interior design or fa fashion, shion, warm colors are said to arouse or stimulate the viewer, while cool colors calm and relax. Most of these effects, to the extent they are real, can be attributed to the higher saturation and lighter value of warm pigments in contrast to cool pigments. Thus, brown is a dark, unsaturated warm color that few people think of as visually active or psychologically arousing. Contrast the traditional warm warm–cool cool association of color with the color temperature of a theoretical radiating black body, where the asso association of color with temperature is reversed. For instance, the hottest stars radiate blue light (i.e., with shorter wavelength and higher frequency), and the coolest radiate red. 1.4.2 Achromatic colors BMG 103: Color Theory Page 14 Any color that lacks strong chromatic content is said to be unsaturated, achromatic, near neutral, or neutral. Near neutrals include browns, tans, pastels and darker colors. Near neutrals can be of any hue or lightness. Pure achromatic, or neutral colors include black, white and all grays. Near neutrals are obtained by mixing pure colors with white, black or grey, or by mixing two complementary colors. In color theory, neutral colors are easily modified by adjacent more saturated colors and they appear to take on the hue complementary to the saturated color; e.g.: next to a bright red couch, a gray wall will appear distinctly greenish. Black and white have long been known to combine "well" with almost any other colors; black decreases the apparent saturation or brightness of colors paired with it, and white shows off all hues to equal effect. 1.4.3 Complementary colors when complementary colors are chosen based on definition by light mixture, they are not the same as the artists' primary colors. This discrepancy becomes important when color theory is applied across media. Digital color management uses a hue circle defined according to additive primary colors (the RGB color model), as the colors in a computer monitor are additive mixtures of light, not subtractive mixtures of paints. One reason the artist's primary colors work at all is that the imperfect pigments being used have sloped absorption curves, and thus change color with concentration. A pigment that is pure red at high concentrations can behave more like magenta at low concentrations. This allows it to make purples that would otherwise be impossible. Likewise, a blue that is ultramarine at high concentrations appears cyan at low concentrations, allowing it to be used to mix green. Chromium red pigments can appear orange, and then yellow, as the concentration is reduced. It is even possible to mix very low concentrations of the blue mentioned and the chromium red to get a greenish color. This works much better with oil colors than it does with watercolors and dyes. 1.4.4 Tints and shades Mixing colored light (additive color models), the achromatic mixture of spectrally balanced red, green and blue (RGB) is always white, not gray or black. When we mix colorants, such as the pigments in paint mixtures, a color is produced which is always darker and lower in chroma, or saturation, than the parent colors. This moves the mixed color toward a neutral color—a gray or near-black. Lights are made brighter or dimmer by adjusting their brightness, or energy level; in painting, lightness is adjusted through mixture with white, black or a color's complement. It is common among some painters to darken a paint color by adding black paint— producing colors called shades—or lighten a color by adding white—producing colors called tints. However it is not always the best way for representational painting, as an unfortunate result is for colors to also shift in hue. For instance, darkening a color by adding black can BMG 103: Color Theory Page 15 cause colors such as yellows, reds and oranges, to shift toward the greenish or bluish part of the spectrum. Lightening a color by adding white can cause a shift towards blue when mixed with reds and oranges. Another practice when darkening a color is to use its opposite, or complementary, color (e.g. purplish-red added to yellowish-green) in order to neutralize it without a shift in hue, and darken it if the additive color is darker than the parent color. When lightening a color this hue shift can be corrected with the addition of a small amount of an adjacent color to bring the hue of the mixture back in line with the parent color (e.g. adding a small amount of orange to a mixture of red and white will correct the tendency of this mixture to shift slightly towards the blue end of the spectrum). 1.4.5 Split Primary Colours If you learn the split-primary color-mixing system, you'll never make mud again, unless you intend to! It's really quite simple. You use just six colors, including two of each primary hue. The trick is in choosing the right colors and then combining them correctly to get the optimum result. The illustration shows you a bright, high-intensity color wheel mixed with split primaries. Here's how it works: Make a circle with a three-legged figure in the center, like a clock with three hands. At the top of the circle (12 o'clock) to the right of the line, place Winsor Lemon or Cadmium Lemon (or another color that looks similarly cool and lemony, but not Lemon Yellow Nickel Titanate. Place New Gamboge, Cadmium Yellow or Indian Yellow to the left of the line. Next, going clockwise around the circle to four o'clock, place Winsor Blue (Green Shade or Red Shade) or Phthalo Blue above the line and French Ultramarine below the line. Continuing clockwise to eight o'clock, place Alizarin Crimson or Permanent Rose below the line and Winsor Red, Permanent Red, Scarlet Lake or Cadmium Red above the line. CHECK YOUR PROGRESS Explain the concept of traditional color theory. Elaborate the importance of warm and cool colors. Discuss the idea of warm and cool colors. Explain the concepts of Achromatic colors. Elaborate the concepts of Tints and shades. Descibe the idea of Split Primary Colors. BMG 103: Color Theory Page 16 1.5 HISTORICAL BACKGROUND Issac Newton (1642 - 1727) : A pioneer in the field of colour, Isaac Newton in 1672, published his first, controversial paper on colour, and forty years later, his work 'Opticks'. Newton passed a beam of sunlight through a prism. When the light came out of the prism is was not white but was of seven different colours: Red, Orange, Yellow, Green, Blue, Indigo and Violet. The spreading into rays was called dispersion by Newton and he called the different coloured rays the spectrum. He learnt that when the light rays were passed again through a prism the rays turned back into white light. If only one ray was passed through the prism it would come out the same colour as it went in. Newton concluded that white light was made up of seven different coloured rays. Color theory was originally formulated in terms of three "primary" or "primitive" colors—red, yellow and blue (RYB)—because these colors were believed capable of mixing all other colors. This color mixing behavior had long been known to printers, dyers and painters, but these trades preferred pure pigments to primary color mixtures, because the mixtures were too dull (unsaturated). The RYB primary colors became the foundation of 18th century theories of color vision, as the fundamental sensory qualities that are blended in the perception of all physical colors and equally in the physical mixture of pigments or dyes. These theories were enhanced by 18th-century investigations of a variety of purely psychological color effects, in particular the contrast between "complementary" or opposing hues that are produced by color afterimages and in the contrasting shadows in colored light. These ideas and many personal color observations were summarized in two founding documents in color theory: the Theory of Colours (1810) by the German poet and government minister Johann Wolfgang von Goethe, and The Law of Simultaneous Color Contrast (1839) by the French industrial chemist Michel Eugène Chevreul. Charles Hayter published A New Practical Treatise on the Three Primitive Colours Assumed as a Perfect System of Rudimentary Information (London 1826), in which he described how all colours could be obtained from just three. Subsequently, German and English scientists established in the late 19th century that color perception is best described in terms of a different set of primary colors—red, green and blue violet (RGB)—modeled through the additive mixture of three monochromatic lights. Subsequent research anchored these primary colors in the differing responses to light by three types of color receptors or cones in the retina (trichromacy). On this basis the quantitative description of color mixture or colorimetry developed in the early 20th century, along with a series of increasingly sophisticated models of color space and color perception, such as the opponent process theory. BMG 103: Color Theory Page 17 Across the same period, industrial chemistry radically expanded the color range of lightfast synthetic pigments, igments, allowing for substantially improved saturation in color mixtures of dyes, paints and inks. It also created the dyes and chemical processes necessary for color photography. As a result, three-color color printing became aesthetically and economically fea feasible in mass printed media, and the artists' color theory was adapted to primary colors most effective in inks or photographic dyes: cyan, magenta, and yellow (CMY). (In printing, dark colors are supplemented by a black ink, known as the CMYK system; in both both printing and photography, white is provided by the color of the paper.) These CMY primary colors were reconciled with the RGB primaries, and subtractive color mixing with additive color mixing, by defining the CMY primaries as substances that absorbed only one of the retinal primary colors: cyan absorbs only red (−R+G+B), −R+G+B), magenta only green (+R−G+B), and yellow only blue violet (+R+G−B). −B). It is important to add that the CMYK, or process, color printing is meant as an economical way of producing a wide range range of colors for printing, but is deficient in reproducing certain colors, notably orange and slightly deficient in reproducing purples. A wider range of color can be obtained with the addition of other colors to the printing process, such as in Pantone's Hexachrome printing ink system (six colors), among others. Fig 1.01: Munsell's color system represented as a three three-dimensional dimensional solid showing all three color making attributes: lightness, saturation and hue. For much of the 19th century artistic color theory theory either lagged behind scientific understanding or was augmented by science books written for the lay public, in particular Modern Chromatics (1879) by the American physicist Ogden Rood, and early color atlases developed by Albert Munsell (Munsell Book of Color, 1915, see Munsell color system) and Wilhelm Ostwald (Color Atlas, 1919). Major advances were made in the early 20th century by artists teaching or associated with the German Bauhaus, in particular Wassily Kandinsky, Johannes Itten, Faber Birren andnd Josef Albers, whose writings mix speculation with an empirical or demonstration-based based study of color design principles. BMG 103: Color Theory Page 18 1.6 COLOUR HARMONY AND COLOUR MEANINGS (Source: http://www.sensationalcolor.com/understanding-color/theory/color- relationships-creating-color-harmony-1849#.WdOxIsZx3IU) Harmony is nature’s way of saying that two or more things together make sense. Color harmony represents a satisfying balance or unity of colors. Combinations of colors that exist in harmony are pleasing to the eye. The human brain distinguishes the visual interest and the sense of order created by the harmony and forms a dynamic equilibrium. Experts have specific ideas based on the principles of color theory and color psychology of color combinations that are aesthetically appealing and pleasant. The color wheel becomes the designer’s tool for creating the harmonies. Just keep in mind, as you learned in “Get to Know the Color Wheel” that it is color relationship reference tool not color selection tool. Once you have a harmony in mind you will then use your a fanguide, chip rack or online tool that shows the hundreds or maybe even thousands of colors you have to chose from. Creating Color Harmony The basic formulas for creating harmony are described and illustrated on the designer’s color wheel. This section focuses on understanding color relationships and how to develop a finished palette that is pleasing to the eye. Successful color schemes rely on your knowledge of hue, value and chroma. We have all heard someone say “those colors clash” or ‘don’t work together.’ What follows are examples of the color harmonies found on the color wheel that all begin with the color yellow as the common color however you could create these harmonies with any of the twelve hues on our color wheel Color Harmonies Monochromatic harmony uses various values (tints, tones, and shades) within the same color family. Analogous harmonies are based on three or more colors that sit side-by-side on the color wheel. Complementary colors (or Direct Complementary) are those that appear opposite each other on the color wheel. A split-complementary color arrangement results from one color paired with two colors on either side of the original color’s direct complement creating a scheme containing three colors. Double complement harmonies include two sets of complementary colors that sit next to and across from each other on the color wheel forming an X. BMG 103: Color Theory Page 19 Use color harmonies along with hue, value, and chroma to develop your color schemes. Color can come first or last in the design process. Some designers prefer to choose each color, identifying the color harmony and color description, then find the other elements for their design. Other designers will do just the opposite and create their color plan by responding to an inspiration or another element of design. Besides taking into consideration color theory: hue, value, chroma, and color harmony, you also need to understand how people might react to the palette on a psychological basis. Learning the meanings and associations of the different colors can assist you in finding just the right colors. Meanings of colours Red is the color of energy, passion, action, ambition and determination. It is also the color of anger and sexual passion. Orange is the color of social communication and optimism. From a negative color meaning it is also a sign of pessimism and superficiality. Yellow is the color of the mind and the intellect. It is optimistic and cheerful. However it can also suggest impatience, criticism and cowardice. Green is the color of balance and growth. It can mean both self-reliance as a positive and possessiveness as a negative, among many other meanings. Blue is the color of trust and peace. It can suggest loyalty and integrity as well as conservatism and frigidity. Indigo is the color of intuition. In the meaning of colors it can mean idealism and structure as well as ritualistic and addictive. Purple is the color of the imagination. It can be creative and individual or immature and impractical. Brown is a friendly yet serious, down-to-earth color that relates to security, protection, comfort and material wealth. Gray is the color of compromise - being neither black nor white, it is the transition between two non-colors. It is unemotional and detached and can be indecisive. Silver has a feminine energy; it is related to the moon and the ebb and flow of the tides - it is fluid, emotional, sensitive and mysterious. Gold is the color of success, achievement and triumph. Associated with abundance and prosperity, luxury and quality, prestige and sophistication, value and elegance, the color psychology of gold implies affluence, material wealth and extravagance. BMG 103: Color Theory Page 20 White is color at its most complete and pure, the color of perfection. The color meaning of white is purity, innocence, wholeness and completion. Black is the color of the hidden, the secretive and the unknown, creating an air of mystery. It keeps things bottled up inside, hidden from the world. CHECK YOUR PROGRESS Explain the concept of color harmony. Elaborate the importance of creating color harmony. Explain the idea of meaning attached to colors. Explain the meaning attached to golden, purple, black, white, indigo, brown, gray, silver and blue colors. 1.7 EMOTIONAL RESPONSE TO COLOURS RED: Physical Positive: Physical courage, strength, warmth, energy, basic survival, 'fight or flight', stimulation, masculinity, excitement. Negative: Defiance, aggression, visual impact, strain. Being the longest wavelength, red is a powerful colour. Although not technically the most visible, it has the property of appearing to be nearer than it is and therefore it grabs our attention first. Hence its effectiveness in traffic lights the world over. Its effect is physical; it stimulates us and raises the pulse rate, giving the impression that time is passing faster than it is. It relates to the masculine principle and can activate the "fight or flight" instinct. Red is strong, and very basic. Pure red is the simplest colour, with no subtlety. It is stimulating and lively, very friendly. At the same time, it can be perceived as demanding and aggressive. BLUE. Intellectual. Positive: Intelligence, communication, trust, efficiency, serenity, duty, logic, coolness, reflection, calm. Negative: Coldness, aloofness, lack of emotion, unfriendliness. BMG 103: Color Theory Page 21 Blue is the colour of the mind and is essentially soothing; it affects us mentally, rather than the physical reaction we have to red. Strong blues will stimulate clear thought and lighter, soft blues will calm the mind and aid concentration. Consequently it is serene and mentally calming. It is the colour of clear communication. Blue objects do not appear to be as close to us as red ones. Time and again in research, blue is the world's favourite colour. However, it can be perceived as cold, unemotional and unfriendly. YELLOW. Emotional Positive: Optimism, confidence, self-esteem, extraversion, emotional strength, friendliness, creativity. Negative: Irrationality, fear, emotional fragility, depression, anxiety, suicide. The yellow wavelength is relatively long and essentially stimulating. In this case the stimulus is emotional, therefore yellow is the strongest colour, psychologically. The right yellow will lift our spirits and our self-esteem; it is the colour of confidence and optimism. Too much of it, or the wrong tone in relation to the other tones in a colour scheme, can cause self-esteem to plummet, giving rise to fear and anxiety. Our "yellow streak" can surface. GREEN. Balance Positive: Harmony, balance, refreshment, universal love, rest, restoration, reassurance, environmental awareness, equilibrium, peace. Negative: Boredom, stagnation, blandness, enervation. Green strikes the eye in such a way as to require no adjustment whatever and is, therefore, restful. Being in the centre of the spectrum, it is the colour of balance - a more important concept than many people realise. When the world about us contains plenty of green, this indicates the presence of water, and little danger of famine, so we are reassured by green, on a primitive level. Negatively, it can indicate stagnation and, incorrectly used, will be perceived as being too bland. VIOLET. Spiritual Positive: Spiritual awareness, containment, vision, luxury, authenticity, truth, quality. Negative: Introversion, decadence, suppression, inferiority. The shortest wavelength is violet, often described as purple. It takes awareness to a higher level of thought, even into the realms of spiritual values. It is highly introvertive and encourages deep contemplation, or meditation. It has associations with royalty and usually communicates the finest possible quality. Being the last visible wavelength before the ultra- violet ray, it has associations with time and space and the cosmos. Excessive use of purple BMG 103: Color Theory Page 22 can bring about too much introspection and the wrong tone of it communicates something cheap and nasty, faster than any other colour. ORANGE. Positive: Physical comfort, food, warmth, security, sensuality, passion, abundance, fun. Negative: Deprivation, frustration, frivolity, immaturity. Since it is a combination of red and yellow, orange is stimulating and reaction to it is a combination of the physical and the emotional. It focuses our minds on issues of physical comfort - food, warmth, shelter etc. - and sensuality. It is a 'fun' colour. Negatively, it might focus on the exact opposite - deprivation. This is particularly likely when warm orange is used with black. Equally, too much orange suggests frivolity and a lack of serious intellectual values. PINK. Positive: Physical tranquillity, nurture, warmth, femininity, love, sexuality, survival of the species. Negative: Inhibition, emotional claustrophobia, emasculation, physical weakness. Being a tint of red, pink also affects us physically, but it soothes, rather than stimulates. (Interestingly, red is the only colour that has an entirely separate name for its tints. Tints of blue, green, yellow, etc. are simply called light blue, light greenetc.) Pink is a powerful colour, psychologically. It represents the feminine principle, and survival of the species; it is nurturing and physically soothing. Too much pink is physically draining and can be somewhat emasculating. GREY. Positive: Psychological neutrality. Negative: Lack of confidence, dampness, depression, hibernation, lack of energy. Pure grey is the only colour that has no direct psychological properties. It is, however, quite suppressive. A virtual absence of colour is depressing and when the world turns grey we are instinctively conditioned to draw in and prepare for hibernation. Unless the precise tone is right, grey has a dampening effect on other colours used with it. Heavy use of grey usually indicates a lack of confidence and fear of exposure. BLACK. Positive: Sophistication, glamour, security, emotional safety, efficiency, substance. Negative: Oppression, coldness, menace, heaviness. BMG 103: Color Theory Page 23 Black is all colours, totally absorbed. The psychological implications of that are considerable. It creates protective barriers, as it absorbs all the energy coming towards you, and it enshrouds the personality. Black is essentially an absence of light, since no wavelengths are reflected and it can, therefore be menacing; many people are afraid of the dark. Positively, it communicates absolute clarity, with no fine nuances. It communicates sophistication and uncompromising excellence and it works particularly well with white. Black creates a perception of weight and seriousness. It is a myth that black clothes are slimming: WHITE. Positive: Hygiene, sterility, clarity, purity, cleanness, simplicity, sophistication, efficiency. Negative: Sterility, coldness, barriers, unfriendliness, elitism. Just as black is total absorption, so white is total reflection. In effect, it reflects the full force of the spectrum into our eyes. Thus it also creates barriers, but differently from black, and it is often a strain to look at. It communicates, "Touch me not!" White is purity and, like black, uncompromising; it is clean, hygienic, and sterile. The concept of sterility can also be negative. Visually, white gives a heightened perception of space. The negative effect of white on warm colours is to make them look and feel garish. BROWN. Positive: Seriousness, warmth, Nature, earthiness, reliability, support. Negative: Lack of humour, heaviness, lack of sophistication. Brown usually consists of red and yellow, with a large percentage of black. Consequently, it has much of the same seriousness as black, but is warmer and softer. It has elements of the red and yellow properties. Brown has associations with the earth and the natural world. It is a solid, reliable colour and most people find it quietly supportive - more positively than the ever-popular black, which is suppressive, rather than supportive. 1.8 PHYSIOLOGICAL PRINCIPLE FOR EFFECTIVE USE OF COLOUR Perception of color begins with specialized retinal cells containing pigments with different spectral sensitivities, known as cone cells. In humans, there are three types of cones sensitive to three different spectra, resulting in trichromatic color vision. Each individual cone contains pigments composed of opsin apoprotein, which is covalently linked to either 11-cis-hydroretinal or more rarely 11-cis-dehydroretinal. The cones are conventionally labeled according to the ordering of the wavelengths of the peaks of their spectral sensitivities: short (S), medium (M), and long (L) cone types. These BMG 103: Color Theory Page 24 three types do not correspond well to particular colors as we know them. Rather, the perception of color is achieved by a complex process that starts with the differential output of these cells in the retina and it will be finalized in the visual cortex and associative areas of the brain. For example, while the L cones have been referred to simply as red receptors, microspectrophotometry has shown that their peak sensitivity is in the greenish-yellowyellow region of the spectrum. Similarly, the S-- and M-cones cones do not directly correspond to blue and green, although they are often described as such. The RGB color model, therefore, is a convenient means for representing color, but is not directly directly based on the types of cones in the human eye.The peak response of human cone cells varies, even among individuals with so so-called normal color vision; in some nonnon-human human species this polymorphic variation is even greater, and it may well be adaptive 1.8.1 Mechanism of dichromatic color vision Trichromatic color vision is the ability of humans and some other animals to see different colors, mediated by interactions among three types of color-sensing color sensing cone cells. The trichromatic color theory began in the 18th century, when Thomas Young proposed that color vision was a result of three different photoreceptor cells. Hermann von Helmholtz later expanded on Young's ideas using color color-matching matching experiments which showed that people with normal vision needed three wavelengths to create the normal range of colors. Physiological evidence for trichromatic theory was later given by Gunnar Svaetichin (1956). Fig 1.02: Normalised responsivity spectra of human cone cells Each of the three types of cones in the retina of the eye contains a different type of photosensitive pigment, which is composed of a transmembrane protein called opsin and a light-sensitive sensitive molecule called 11 11-cis cis retinal. Each different pigment is especially sensitive to a certain wavelength of light (that at is, the pigment is most likely to produce a cellular response when it is hit by a photon with the specific wavelength to which that pigment is most sensitive). The three types of cones are L, M, and S, which have pigments that respond best to light of long ong (especially 560 nm), medium (530 nm), and short (420 nm) wavelengths BMG 103: Color Theory Page 25 respectively. Since the likelihood of response of a given cone varies not only with the wavelength of the light that hits it but also with its intensity, the brain would not be able to discriminate different colors if it had input from only one type of cone. Thus, interaction between at least two types of cone is necessary to produce the ability to perceive color. With at least two types of cones, the brain can compare the signals from each type and determine both the intensity and color of the light. For example, moderate stimulation of a medium- wavelength cone cell could mean that it is being stimulated by very bright red (long- wavelength) light, or by not very intense yellowish-green light. But very bright red light would produce a stronger response from L cones than from M cones, while not very intense yellowish light would produce a stronger response from M cones than from other cones. Thus trichromatic color vision is accomplished by using combinations of cell responses. It is estimated that the average human can distinguish up to seven million different colors 1.8.2 Human Visual System Solving the problem of converting light into ideas, of visually understanding features and objects in the world, is a complex task far beyond the abilities of the world's most powerful computers. Vision requires distilling foreground from background, recognizing objects presented in a wide range of orientations, and accurately interpreting spatial cues. The neural mechanisms of visual perception offer rich insight into how the brain handles such computationally complex situations. Visual perception begins as soon as the eye focuses light onto the retina, where it is absorbed by a layer of photoreceptor cells. These cells convert light into electrochemical signals, and are divided into two types, rods and cones, named for their shape. Rod cells are responsible for our night vision, and respond well to dim light. Rods are found mostly in the peripheral regions of the retina, so most people will find that they can see better at night if they focus their gaze just off to the side of whatever they are observing. Cone cells are concentrated in a central region of the retina called the fovea; they are responsible for high acuity tasks like reading, and also for color vision. Cones can be subcategorized into three types, depending on how they respond to red, green, and blue light. In combination, these three cone types enable us to perceive color. BMG 103: Color Theory Page 26 fovea : The fovea ovea centralis (the term fovea comes from the Latin, meaning pit or pitfall) is a small, central pit composed of closely packed cones in the eye. It is located in the center of the macula lutea of the retina. Blind Spot:: The area of the retina where the optic optic nerve is attached is completely devoid of photosensitive cells. This means that there is a “blind spot” in the field of vision for each eye. Most of the time we are not aware of this deficit in our vision, but it is quite easy to locate it. 1.8.3 Phototransduction transduction There is more than what can be see... Vision Signal Transduction Pathway Cell Signal Transduction Pathway Eye Structure and Vision Pathway Rods signal tranduction pathway Structure of Rods and Cones Retina Structure/Function Cornea: the trans transparent parent most outer part of the eye, this is where mucles attached to move the eye. Iris: controls the light level that enters the eye. Optic Nerve: carry signals from back of the eye to the brain. Focal Point: Where it collects all the rays of light. Retina: Retina: inner most layer, contains photoreceptors (rods and cones) and neurons which the photoreceptors act upon. Crystalline lens: Refracts light to be focus in the retina Ligand: ""the messenger" light travels through cornea > iris > lens > focal point > retinaa > optic nerve > brain 1.8.5 Difference between Rods and Cones BMG 103: Color Theory Page 27 Properties of Rod and Cone Systems Rods Cones Comment More photopigment Less photopigment Slow response: long Fast response: short Temporal integration integration time integration time Single quantum detection High amplification Less amplification in rods (Hecht, Schlaer & Pirenne) The rods' response saturates when only a small amount of the pigment is Saturating Response (by Non-saturating response bleached (the absorption of a 6% bleached) (except S-cones) photon by a pigment molecule is known as bleaching the pigment). Not directionally Stiles-Crawford effect (see Directionally selective selective later this chapter) Highly convergent Less convergent retinal Spatial integration retinal pathways pathways Lower absolute High sensitivity sensitivity Results from degree of Low acuity High acuity spatial integration Color vision results from Achromatic: one type of Chromatic: three types comparisons between cone pigment of pigment responses 1.8.6 Function Photoreceptors do not signal color; they only signal the presence of light in the visual field. A given photoreceptor responds to both the wavelength and intensity of a light source. For example, red light at a certain intensity can produce the same exact response in a photoreceptor as green light of a different intensity. Therefore, the response of a single photoreceptor is ambiguous when it comes to color. To determine color, the visual system compares responses across a population of photoreceptors (specifically, the three different cones with differing absorption spectra). To determine intensity, the visual system computes BMG 103: Color Theory Page 28 how many photoreceptors are responding. This is the mechanism that allows trichromatic color vision in humans and some other animals. 1.8.7 Signaling The rod and cone photoreceptors signal their absorption of photons via a decrease in the release of the neurotransmitter glutamate to bipolar cells at its axon terminal. Since the photoreceptor is depolarized in the dark, a high amount of glutamate is being released to bipolar cells in the dark. Absorption of a photon will hyperpolarize the photoreceptor and therefore result in the release of less glutamate at the presynaptic terminal to the bipolar cell. Every rod or cone photoreceptor releases the same neurotransmitter, glutamate. However, the effect of glutamate differs in the bipolar cells, depending upon the type of receptor imbedded in that cell's membrane. When glutamate binds to an ionotropic receptor, the bipolar cell will depolarize (and therefore will hyperpolarize with light as less glutamate is released). On the other hand, binding of glutamate to a metabotropic receptor results in a hyperpolarization, so this bipolar cell will depolarize to light as less glutamate is released. In essence, this property allows for one population of bipolar cells that gets excited by light and another population that gets inhibited by it, even though all photoreceptors show the same response to light. This complexity becomes both important and necessary for detecting color, contrast, edges, etc. Further complexity arises from the various interconnections among bipolar cells, horizontal cells, and amacrine cells in the retina. The final result is differing populations of ganglion cells in the retina, a sub-population of which is also intrinsically photosensitive, using the photopigment melanopsin. 1.8.8 Ganglion cell In humans the retinal ganglion cell photoreceptor contributes to conscious sight as well as to non-image-forming functions like circadian rhythms, behaviour and pupil reactions. Since these cells respond mostly to blue light, it has been suggested that they have a role in mesopic vision. Zaidi and colleagues' work with rodless coneless human subjects hence also opened the door into image-forming (visual) roles for the ganglion cell photoreceptor. It was discovered that there are parallel pathways for vision – one classic rod and cone-based pathway arising from the outer retina, and the other a rudimentary visual brightness detector pathway arising from the inner retina, which seems to be activated by light before the other. Classic photoreceptors also feed into the novel photoreceptor system, and colour constancy may be an important role as suggested by Foster. The receptor could be instrumental in understanding many diseases including major causes of blindness worldwide like glaucoma, a disease that affects ganglion cells, and the study of the receptor offered potential as a new avenue to explore in trying to find treatments for blindness. It is in these discoveries of the novel photoreceptor in humans and in the receptors role in vision, rather than its non-image- forming functions, where the receptor may have the greatest impact on society as a whole, though the impact of disturbed circadian rhythms is another area of relevance to clinical medicine. BMG 103: Color Theory Page 29 Most work suggests that the peak spectral sensitivity of the receptor is between 460 and 482 nm. Steven Lockley et al. in 2003 showed that 460 nm wavelengths of light suppress melatonin twice as much as longer 555 nm light. However, in more recent work by Farhan Zaidi et al., using rodless coneless humans, it was found that what consciously led to light perception was a very intense 481 nm stimulus; this means that the receptor, in visual terms, enables some rudimentary vision maximally for blue light. CHECK YOUR PROGRESS Explain the physiological basis for color perception in humans. Elaborate the importance of Mechanism of dichromatic and tri-chromatic color vision. Explain the features of Human Visual System. Describe the concept of Phototransduction Discuss the difference between Rods and Cones. Explain the functions of photoreceptors. Explain the signaling mechanism of photoreceptors. Explain the functions of Ganglion cell. Explain the functions of photoreceptors. 1.9 LENS The lens is a transparent, biconvex (lentil-shaped) structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a sharp real image of the object of interest to be formed on the retina. This adjustment of the lens is known as accommodation (see also Accommodation, below). It is similar to the focusing of a photographic camera via movement of its lenses. The lens is also known as the aquula (Latin, a little stream, dim. of aqua, water) or crystalline lens. In humans, the refractive power of the lens in its natural environment is approximately 18 dioptres, roughly one-third of the eye's total power. BMG 103: Color Theory Page 30 1.9.1 Position, size, and shape The lens is located in the anterior segment of the eye. Anterior to the lens is the iris, which regulates the amount of light entering the eye. The lens is suspended in place by the zonular fibers, which attach to the lens near its equatorial line and connect the lens to the ciliary body. Posterior to the lens is the vitreous body. The lens has an ellipsoid, biconvex shape. In the adult, the lens is typically 10 mm in diameter and has an axial length of 4 mm, though it is important to note that the size and shape can change due to accommodation and because the lens continues to grow throughout a person’s lifetime. 1.9.2 Lens Structure and Function The lens is comprised of three main parts: the lens capsule, the lens epithelium, and the lens fibers. The lens capsule forms the outermost layer of the lens and the lens fibers form the bulk of the interior of the lens. The cells of the lens epithelium, located between the lens capsule and the outermost layer of lens fibers, are found only on the anterior side of the lens. Lens Capsule The lens capsule is a smooth, transparent basement membrane that completely surrounds the lens. It is synthesized by the lens epithelium and its main components are Type IV collagen and sulfated glycosaminoglycans (GAGs). The capsule is very elastic and so causes the lens to assume a more globular shape when not under the tension of the zonular fibers, which connect the lens capsule to the ciliary body. The capsule varies from 2-28 microns in thickness, being thickest near the equator and thinnest near the posterior pole. Lens Epithelium The lens epithelium, located in the anterior portion of the lens between the lens capsule and the lens fibers, is a simple cuboidal epithelium. The cells of the lens epithelium regulate most of the homeostatic functions of the lens. As ions, nutrients, and liquid enter the lens from the aqueous humor, Na+/K+ ATPase pumps in the lens epithelial cells pump ions out of the lens to maintain appropriate lens osmolarity and volume, with equatorially positioned lens epithelium cells contributing most to this current. The activity of the Na+/K+ ATPases keeps water and current flowing through the lens from the poles and exiting through the equatorial regions. The cells of the lens epithelium also serve as the progenitors for new lens fibers. Lens fibers The lens fibers form the bulk of the lens. They are long, thin, transparent cells, with diameters typically between 4-7 microns and lengths of up to 12 mm long. The lens fibers stretch lengthwise from the posterior to the anterior poles and are arranged in concentric BMG 103: Color Theory Page 31 layers rather like the layers of an onion. These tightly packed layers of lens fibers are referred to as laminae. The lens fibers are linked together via gap junctions and interdigitations of the cells that resemble “ball and socket” forms. The lens is split into regions depending on the age of the lens fibers of a particular layer. Moving outwards from the central, oldest layer, the lens is split into an embryonic nucleus, the fetal nucleus, the adult nucleus, and the outer cortex. New lens fibers, generated from the lens epithelium, are added to the outer cortex. Mature lens fibers have no organelles or nuclei. 1.9.3 Accommodation: changing the power of the lens An image that is partially in focus, but mostly out of focus in varying degrees. The lens is flexible and its curvature is controlled by ciliary muscles through the zonules. By changing the curvature of the lens, one can focus the eye on objects at different distances from it. This process is called accommodation. At short focal distance the ciliary muscles contract, zonule fibers loosen, and the lens thickens, resulting in a rounder shape and thus high refractive power. Changing focus to an object at a distance requires the stretching of the lens by the ciliary muscles, which flattens the lens and thus increases the focal distance. The refractive index of the lens varies from approximately 1.406 in the central layers down to 1.386 in less dense cortex of the lens. This index gradient enhances the optical power of the lens. Aquatic animals must rely entirely on their lens for both focusing and to provide almost the entire refractive power of the eye as the water-cornea interface does not have a large enough difference in indices of refraction to provide significant refractive power. As such, lenses in aquatic eyes tend to be much rounder and harder. 1.9.4 Crystallins and Transparency Crystallins are water-soluble proteins that comprise over 90% of the protein within the lens. The three main crystallin types found in the eye are α-, β-, and γ-crystallins. Crystallins tend to form soluble, high-molecular weight aggregates that pack tightly in lens fibers, thus increasing the index of refraction of the lens while maintaining its transparency. β and γ crystallins are found primarily in the lens, while subunits of α -crystallin have been isolated from other parts of the eye and the body. α-crystallin proteins belong to a larger superfamily of molecular chaperone proteins, and so it is believed that the crystallin proteins were evolutionarily recruited from chaperone proteins for optical purposes. The chaperone functions of α -crystallin may also help maintain the lens proteins, which must last a human for his/her entire lifetime. BMG 103: Color Theory Page 32 Another important factor in maintaining the transparency of the lens is the absence of light-scattering organelles such as the nucleus, endoplasmic reticulum, and mitochondria within the mature lens fibers. Lens fibers also have a very extensive cytoskeleton that maintains the precise shape and packing of the lens fibers; disruptions/mutations in certain cytoskeletal elements can lead to the loss of transparency. CHECK YOUR PROGRESS Explain the physiological aspects of lens in a human eye. Elaborate the importance of position, size and shape of human eye lens. Explain the Structure and Function of human lens. Describe the concept of Lens Epithelium. Discuss the Lens Capsule. Explain the functions of Lens fibers. Explain the accommodation mechanism of human lens. Explain the functions of Crystallins and mechanism of maintaining Transparency in human lens. 1.10 RETINA The retina is the third and inner coat of the eye which is a light-sensitive layer of tissue. The optics of the eye create an image of the visual world on the retina (through the cornea and lens), which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical events that ultimately trigger nerve impulses. These are sent to various visual centres of the brain through the fibres of the optic nerve. Neural retina typically refers to three layers of neural cells (photo receptor cells, bipolar cells, and ganglion cells) within the retina, while the entire retina refers to these three layers plus a layer of pigmented epithelial cells. In vertebrate embryonic development, the retina and the optic nerve originate as outgrowths of the developing brain, specifically the embryonic diencephalon; thus, the retina is considered part of the central nervous system (CNS) and is actually brain tissue. It is the only part of the CNS that can be visualized non-invasively. The retina is a layered structure with several layers of neurons interconnected by synapses. The only neurons that are directly sensitive to light are the photoreceptor cells. For BMG 103: Color Theory Page 33 vision, these are of two types: the rods and cones. Rods function mainly in dim light and provide black-and-white vision while cones support the perception of colour. A third type of photoreceptor, the photosensitive ganglion cells, is important for entrainment and reflexive responses to the brightness of light. Neural signals from the rods and cones undergo processing by other neurons of the retina. The output takes the form of action potentials in retinal ganglion cells whose axons form the optic nerve. Several important features of visual perception can be traced to the retinal encoding and processing of light. Structure The vertebrate retina has ten distinct layers. From closest to farthest from the vitreous body - that is, from closest to the front exterior of the head towards the interior and back of the head: Inner limiting membrane – basement membrane elaborated by Müller cells Nerve fibre layer – axons of the ganglion cell nuclei (note that a thin layer of Müller cell footplates exists between this layer and the inner limiting membrane) Ganglion cell layer – contains nuclei of ganglion cells, the axons of which become the optic nerve fibres for messages and some displaced amacrine cells Inner plexiform layer – contains the synapse between the bipolar cell axons and the dendrites of the ganglion and amacrine cells. Inner nuclear layer – contains the nuclei and surrounding cell bodies (perikarya) of the amacrine cells, bipolar cells and horizontal cells. Outer plexiform layer – projections of rods and cones ending in the rod spherule and cone pedicle, respectively. These make synapses with dendrites of bipolar cells. In the macular region, this is known as the Fiber layer of Henle. Outer nuclear layer – cell bodies of rods and cones External limiting membrane – layer that separates the inner segment portions of the photoreceptors from their cell nucleus Layer of rods and cones – layer of rod cells and cone cells Retinal pigment epithelium - single layer of cuboidal cells (with extrusions not shown in diagram). This is closest to the choroid. These can be simplified into 4 main processing stages: photoreception, transmission to bipolar cells, transmission to ganglion cells which also contain photoreceptors, the photosensitive ganglion cells, and transmission along the optic nerve. At each synaptic stage there are also laterally connecting horizontal and amacrine cells. Rods, cones and nerve layers in the retina. The front (anterior) of the eye is on the left. Light (from the left) passes through several transparent nerve layers to reach the rods and cones (far right). A chemical change in the rods and cones send a signal back to the nerves. The signal goes first to the bipolar and horizontal cells (yellow layer), then to the amacrine cells and ganglion cells (purple layer), then to the optic nerve fibres. The signals are BMG 103: Color Theory Page 34 processed in these layers. First, the signals start as raw outputs of points in the rod and cone cells. Then the nerve layers identify simple shapes, such as bright points surrounded by dark points, edges, and movement Diseases and disorders of the eye Retinitis Pigmentosa : A group of inherited disorders of the retina (the light-sensitive lining at the back of the eye), which cause poor night vision and a progressive loss of side vision. Macular Degeneration : An eye disease affecting the macula (the center of the light- sensitive retina at the back of the eye), causing loss of central vision. Retinoblastoma : A rare type of eye cancer occurring in young children that develops in the retina, the light-sensitive lining at the back of the eye. Color Blindness : Color blindness is not actually blindness in the true sense but rather is a color vision deficiency—people who are affected by it simply do not agree with most other people about color matching. Red–green color blindness : Protanopia, deuteranopia, protanomaly, and deuteranomaly are commonly inherited forms of red–green color blindness which affect a substantial portion of the human population. Those affected have difficulty with discriminating red and green hues due to the absence or mutation of the red or green retinal photoreceptors. Blue–yellow color blindness : Those with tritanopia and tritanomaly have difficulty discriminating between bluish and greenish hues, as well as yellowish and reddish hues. Color blindness involving the inactivation of the short-wavelength sensitive cone system (whose absorption spectrum peaks in the bluish-violet) is called tritanopia or, loosely, blue– yellow color blindness. Total color blindness : Total color blindness is defined as the inability to see color. Although the term may refer to acquired disorders such as cerebral achromatopsia also known as color agnosia, it typically refers to congenital color vision disorders (i.e. more frequently rod monochromacy and less frequently cone monochromacy) CHECK YOUR PROGRESS Explain the physiological aspects of retina in a human eye. Elaborate the importance of position, size and shape of human retina. Explain the diseases in human eyes. Describe the concept of color blindness and their types. BMG 103: Color Theory Page 35 1.11 HUMAN BRAIN The human brain is the command center for the human nervous system. It receives input from the sensory organs and sends output to the muscles. The human brain has the same basic structure as other mammal brains, but is larger in relation to body size than any other brains. Facts about the human brain The human brain is the largest brain of all vertebrates relative to body size It weighs about 3.3 lbs. (1.5 kilograms) The brain makes up about 2 percent of a human's body weight The cerebrum makes up 85 percent of the brain's weight It contains about 86 billion nerve cells (neurons) — the "gray matter" It contains billions of nerve fibers (axons and dendrites) — the "white matter" These neurons are connected by trillions of connections, or synapses Parts of the brain The brain is divided into three major regions - the hindbrain, the midbrain and the forebrain. Each region is composed of different brain parts that work together to process the information they receive. Forebrain : The Forebrain is considered as the highest region of the brain because it essentially differentiates us humans from the rest in the animal kingdom. This region is also involved in processing complex information. Midbrain :The Midbrain serves to relay information between the hindbrain and the forebrain, particularly information coming from the eyes and the ears. The reticular formation is involved with stereotypical patterns of behavior such as walking, sleeping, and other reflexes. Parkinson's disease, a degenerative disease of the brain that causes involuntary tremors on affected body parts, damages a section near the bottom of the midbrain. Hindbrain : It is involved in alertness and in monitoring basic survival functions such as breathing, heartbeat, and blood pressure. It is also known as the "reptilian brain" because it is considered the entire brain of reptiles. Cerebral Cortex The cerebral cortex is divided into two hemispheres - the left and the right hemispheres. The left hemisphere is associated with verbal processing, such as speech and grammar, and mathematics; while the right hemisphere is involved with nonverbal processing, such as spatial perception, visual recognition and emotion. The left hemisphere processes information coming from the right side of the body, while the right hemisphere processes information coming from the left side of the body. The two hemispheres of the brain are connected with BMG 103: Color Theory Page 36 each other by a bundle of axons called the corpus callosum. This connection allows the left and the right hemispheres to communicate and integrate information with each other. CHECK YOUR PROGRESS Explain the physiological aspects of human brain. Elaborate the importance parts of human brain. Explain the features of cerebral cortex. 1.12 EFFECTIVE USE OF COLOURS I believe that effective use of colour is key to a successful and accessible website. Communication and brand recognition is greatly aided by the use of a simple, relevant and effective colour scheme throughout the site. Optimising design for the screen based medium is something many print designers take a while to get to grips with as designing for websites involves dealing with backlit luminescence, which can vary from monitor to monitor and from platform to platform. Colours are RGB not CMYK. Therefore effective and use of limited colour with emphasis on contrast is very important. An understanding of how certain colours perform on screen compared to when they are printed helps avoid communication and branding mistakes. In general it's a good idea to restrict the number of colours used and isolating areas involving large amount of colour variation i.e. colour-coded section dividers, navigation elements and photography. Other points to note are that: large areas of text are more readable on black on white than white on black. Sites can involve movement as well as clever use of colour to emphasise important points and branding truths. Understand your audience Understand your site's message and brand Choose colours that reinforce your message. For instance, if designing a site for a financial institution hoping to convey stability, choose cool, muted colours such as blue, grey, and green. In this case, using warm, vibrant hues would undermine the site's brand. Cultural differences can lead to unexpected responses to colour. Additionally, demographic segments and age groups respond to colours differently. Younger audiences generally respond to more saturated hues that are less effective with older segments. Use contrast for readability BMG 103: Color Theory Page 37 Colours similar in value do not provide enough contrast and hinder legibility and accessibility. Black text on white backgrounds provides the highest degree of contrast. CHECK YOUR PROGRESS Explain the aspects of making effective use of colors. Elaborate the importance of making effective use of colors. Explain the importance of contrast and readability. 1.14 SUMMARY A basic knowledge of colour theory definitely helps in making a harmonious combination which is pleasing to the eyes. With the basic knowledge of colour theory, one can easily understand how to make effective use of colours in our daily life. For a person who belongs to art background, judgement about colours and their meaning is easy. For a lay man visualizing colours is not an easy task. A poor and undeveloped sense of colour proves to be a great hindrance in making good colour decisions. In the visual arts, colour theory refers to the visual impact created by different types of colours, both individually and in combination with each other. Colour balance refers to the use of congruous colours in a design. Colour scheme is the choice of colours used in a design for a range of media used in colour theory. Colour schemes are basically used to create style and appeal Complementary colour scheme includes a combination of any two colours that me positioned opposite to each other on the colour wheel Analogous colours appear non to each other on the colour wheel Warm colours are bright and pleasing. They are generally associated with daylight and cool colours with night. Colour theory helps us to understand the various possible combinations that would look harmonious together. An organism's retina comprises three different types of colour receptors called cone cells with BMG 103: Color Theory Page 38 different absorption spectra Trichromatic colour vision is the natural aptitude of humans and some other animals to see different co burs, interposed by interactions among three types of colour-sensing cone cells. A photoreceptor is a specialized type of nerve cell that is capable of phototransduction. Phototransduction is the composite process through which the energy of a photon is utilized to alter the intrinsic membrane potential of the photoreceptor. Signals are conducted by polarization and depolarization of the neurons. One of the most important differences between rods and cones is that while rods are meant for scotopic vision, while cones are responsible for photopic Corpus callosum: The thick band of fibres that connect the left and right brain hemispheres. Fissure of Sylvus: The parietal and temporal lobes of the cerebral cortex are separated by a deep grove called the "Fissure of Sylvus" Colour blindness: An unnatural condition induced by the inability to distinguish clearly between colours of the spectrum Monochromacy: Takes place when two or all three of the cone pigments are not present and colour and light vision is decreased to one dimension. Rod monochromicy: A rare, non-progressive colour blindness whereby it is unable to differentiate any colour as a result of absence of mini cones or non-functional retinal cones. Tritanopia: A generally rare colour vision disturbance in which there are only two cone pigments present and the blue retinal receptors are totally absent, Tritanomaly: A rare type of hereditary colour Wildness where colour vision deficiency causes blue yellow hue discrimination. 1.15 END QUESTIONS 1. Explain the concept of Color Balancing. 2. Elaborate the importance of Color Balancing. 3. Explain the concept of Color Scheme. 4. Elaborate the importance of Color Scheme. 5. Explain the idea of Complementary color scheme. 6. Explain the idea of Complementary color scheme. 7. Explain the idea of Analogous color scheme. 8. Explain the idea of Triadic color scheme. 9. Explain the idea of Split-Complementary color scheme. 10. Explain the idea of Rectangle (tetradic) color scheme. 11. List the various areas where designers give importance to color schemes BMG 103: Color Theory Page 39 12. Explain the concept of traditional color theory. 13. Elaborate the importance of warm and cool colors. 14. Discuss the idea of warm and cool colors. 15. Explain the concepts of Achromatic colors. 16. Elaborate the concepts of Tints and shades. 17. Descibe the idea of Split Primary Colors. 18. Explain the concept of color harmony. 19. Elaborate the importance of creating color harmony. 20. Explain the idea of meaning attached to colors. 21. Explain the meaning attached to golden, purple, black, white, indigo, brown, gray, silver and blue colors. 22. Explain the physiological basis for color perception in humans. 23. Elaborate the importance of Mechanism of dichromatic and tri-chromatic color vision. 24. Explain the features of Human Visual System. 25. Describe the concept of Phototransduction 26. Discuss the difference between Rods and Cones. 27. Explain the functions of photoreceptors. 28. Explain the signaling mechanism of photoreceptors. 29. Explain the functions of Ganglion cell. 30. Explain the functions of photoreceptors. 31. Explain the physiological aspects of lens in a human eye. 32. Elaborate the importance of position, size and shape of human eye lens. 33. Explain the Structure and Function of human lens. 34. Describe the concept of Lens Epithelium. 35. Discuss the Lens Capsule. 36. Explain the functions of Lens fibers. 37. Explain the accommodation mechanism of human lens. 38. Explain the functions of Crystallins and mechanism of maintaining Transparency in human lens. 39. Explain the physiological aspects of retina in a human eye. 40. Elaborate the importance of position, size and shape of human retina. 41. Explain the diseases in human eyes. 42. Describe the concept of color blindness and their types 43. Explain the physiological aspects of human brain. 44. Elaborate the importance parts of human brain. 45. Explain the features of cerebral cortex. 46. Explain the aspects of making effective use of colors. 47. Elaborate the importance of making effective use of colors. 48. Explain the importance of contrast and readability. BMG 103: Color Theory Page 40 UNIT 2: COLOUR BASICS 2.0 INTRODUCTION With colors you can set a mood, attract attention, or make a statement. You can use color to energize, or to cool down. By selecting the right color scheme, you can create an ambiance of elegance, warmth or tranquility, or you can convey an image of playful youthfulness. Color can be your most powerful design element if you learn to use it effectively. Colors affect us in numerous ways, both mentally and physically. A strong red color has been shown to raise the blood pressure, while a blue color has a calming effect. Being able to use colors consciously and harmoniously can help you create spectacular results. Understanding of color basics is extremely important for you as a student and as a professional in media, graphics and animation. Which color to ch

BMG 103 Color Theory PDF - 2017

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