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Color theory

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Describes the Color Theory History.
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Color theory

  1. 1. 1 Color Theory SOLO HERMELIN Updated: 30.09.10http://www.solohermelin.com
  2. 2. 2 Table of Content SOLO Color Theory
  3. 3. 3 Visible Light SOLO Color Theory
  4. 4. 4 Visible Light SOLO Color Theory
  5. 5. 5 SOLO Optics - Eye The human eye is a camera The human eye is able to detect from about 390 to 780 nanometers, defining the visual spectrum http://www.olympusmicro.com/primer/anatomy/introduction.html
  6. 6. Color TheorySOLO Human Eye Color Sensitivity • Maximal Luminance response at ~ 5 cycles/degrees • Little Luminance response above ~ 100 cycles/degrees • Little Luminance response at low frequencies Humans are bad at estimating absolute luminance levels as long as they do not change with time.
  7. 7. Color TheorySOLO Human Eye Color Sensitivity HUMAN EYE COLOR SENSITIVITY & PERCEPTION Human Eye contains Rods ( which see Black & White ) & 3 Types of Color Sensitive Cones - sensitive to "Blue" ( Violet ), "Green" ( Cyan ), & "Red" ( Green ). By Cone Types combining relative Light Intensities, Color is perceived. Combined response of Cones is Eye Luminous Efficiency. Individual differences in Visual Sensitivity result in different Color Perception
  8. 8. 8 SOLO Optics - Eye 1=Iris The colored part of the eye located between the Lens and Cornea. It regulates the entrance of the light. 2 = Cornea The transparent, blood-free tissue covering the central front of the eye that initially refracts or bends light rays as light enters the eye. Contact lenses are fitted over the Cornea. 3 = Retina The innermost layer of the eye, a neurological tissue, which receives light rays focused on it by the Lens. This tissue contains receptor cells (Rods and Cones) that send electrical impulses to the brain via the optic nerve when the light rays are present. 4 = Rods The receptor cells which are sensitive to light and are located in the Retina of the eye. They are responsible for night vision, as non-color vision in low level light. 5 = Cones The receptor cells which are sensitive to light and are located in the Retina of the eye. They are responsible for color vision. Most humans have three types of cones with spectral sensitivity in the short (S), middle (M) and long (L) part of the visible spectrum, and hence are called trichromats. Absorption of a photon leads to a structural change of photo pigment, which – through an enzymatic cascade – generates the electrical cone signal. In this process information about the wavelength of the photon is lost. 6 = Lens The eye's natural Lens. Transparent, biconvex intraocular tissue that helps bring rays of light to a focus on the Retina. 7 = Pupil The opening at the center of the Iris of the eye. It contracts in a high level of light and when the eye is focused on a distant object.
  9. 9. 9 SOLO Color Theory Finland - The oldest known color system is credited to astronomer, priest and Neoplatonist Aron Sigfrid Forsius (1569-1637). In his color circle , between the colors Black and White, Red has been placed on the one side since the classical antiquity, and Blue on the other; Yellow then comes between White and Red, pale Yellow between White and Yellow, Orange between Yellow and Red. http://www.coloryourcarpet.com/History/ColorHistory.html The oldest colour system known today that's worth its name originates from the Finnish born astronomer, priest and Neoplatonist Aron Sigfrid Forsius (died 1637), sometimes also known as Siegfried Aronsen. Forsius became Professor of Astronomy in Uppsala (Sweden) in 1603, later moving as a preacher to Stockholm and beyond. He was removed from office in 1619, after being accused of making astrological prophesies. Eight years previously, a manuscript had appeared in which Forsius expounded his thoughts about colours, concluding that they could be brought into a spacial order. This 1611 text lay undiscovered in the Royal Library in Stockholm until this century, to eventually be presented before the first congress of the "International Colour Association" in 1969. It was in chapter VII — which was devoted to sight — of this work on physics that Forsius introduced his colour diagrams. He first of all discusses the five human senses, explains (for us in rather complicated and incomprehensible terms) how colours are seen, and then arrives at his colour diagrams, on the basis of which he attempts to provide a three-dimensional picture. Forsius states: "Amongst the colours there are two primary colours, white and black, in which all others have their origin." Forsius is here in agreement with Leonardo da Vinci who, more than three hundred years earlier, had included black and white amongst the colours, seeing them next to yellow, red, blue and green as primary colours. Forsius then continues: http://www.colorsystem.com/projekte/engl/03fore.htm 1611 Aron Sigfrid Forsius )1569-1637.(
  10. 10. 10 Optics HistorySOLO 1613 François d'Aguilon (also d'Aguillon or Aguilonius) (1546 - 1617) was a Belgian mathematician and physicist. .... His book, “Opticorum Libri Sex philosophis juxta ac mathematicis utiles” (Six Books of Optics, useful for philosophers and mathematicians alike), published in Antwerp in 1613, was illustrated by famous painter Peter Paul Rubens. http://en.wikipedia.org/wiki/Fran%C3%A7ois_d'Aguilon Anguilonius’ system uses three basic colours, and can thus be seen as the forerunner of other systems which function in a similar way. In the pure combination of colors, he dispenses with the fourth, green, which had already caused difficulties for Leonardo da Vinci, but not without granting it a special position. In the same way as red (above), green is placed in the middle (although beneath). Both colours therefore stand opposite one another, and rightly so, since they do this in a complementary way, as Aguilonius quietly implies when he allocates a tip (a point) to red, whilst green is allowed to extend outwards as a bow. Thus, a restrained point of colour stands opposite the continuous colored line, to be combined using the stepped diagram. http://www.colorsystem.com/projekte/engl/04ague.htm François d‘Aguilon's color mixing theory (1613) http://www.handprint.com/HP/WCL/color6.html Peter Paul Rubens frontispiece of Aguilon's book François d'Aguilon 1567-1617
  11. 11. 11 SOLO Color Theory Color music intended for instrumental performance in conjunction with a simultaneous projection of changing colors onto a screen. Athanasius Kircher said that each musical sound has a necessary, objective correspondence to a certain color. 1646 Athanasius Kircher published in 1646 a book, specifically devoted to colours — The Great Art of Light and Shadow ("Ars magna lucis et umbrae"). The first two words of the Latin title clearly point to the art of Raimundus Lullus, which will be described later (Ars magna). No wonder, therefore, that his system provides a firm idea of mixed colours, characterised by semi-circular bows. The basis for all combinations is a linear construction which, apart from white (albus) and black (niger), operates with three colours, namely yellow (flavus), red (rubeus) and blue (caeruleus). We have no need to account for all arrangements here, and neither should we attempt the translation of all the many new names — subrubeus, for example, or fuscus, or incarnatus. The special position of green (virides) is noteworthy, however: like red, green is placed in the centre, although on the plane of the mixed colours, and not the pure colours. Green is located at the overlap of yellow and blue. If we draw the bows running from white so that they are directed upwards, and the curves running to black so that they are directed downwards, an image will be created which resembles the Chinese Yin-Yang (to create this symbol, we need only retain the route through red, while omitting the lines passing through yellow and blue). As our illustration shows, all the colour points of the system can then be reached from white and black; with that it's author's fundamental view will become apparent. In fact, Kircher views colour as a "genuine product of light and shadow", as he says in the forward to his 1646 book, adding that colour is "shadowed light" and "everything in the world is visible only by means of shadowed light or illuminated shadow." )1601–1680(
  12. 12. 12 SOLO Color Theory England - Isaac Newton (1642-1726) devises the first color wheel . His theory "Optics" had the right idea, dividing the prism and bringing it back together again. However he choses the wrong colors, magenta and cyan were missing. Magenta doesn't show up in a crystal spectrum. It was 32 years later before his color theory was published. English physicist, mathematician, and natural philosopher, considered one of the most important scientists of all time. Newton showed that a prism could break up white light into a range of colors. Newton used the seven color names red, orange, yellow, green, blue, indigo, and violet for segments of the spectrum by analogy with the seven notes of the musical scale. Isaac Newton )1642-1726( http://home.wanadoo.nl/paulschils/08.00.html 1666 http://www.coloryourcarpet.com/History/ColorHistory.html
  13. 13. 13 SOLO Color Theory 1731-France - Jacques Christopher Le Blon, (1667-1742), invented the fundamental three-color palette and demonstrated his system with many dyes, however he did not extend his ideas to a properly organised colour-system. Jacob Christoph Le Blon was a German-born painter and engraver who invented the system of three-color and four-color printing (similar to the modern CMYK system).He used several metal plates (each for an individual color) for making prints with a wide range of colors. His methods formed the foundation for modern color printing. His names are sometimes spelled Jakob, Jacques, Christophe, Leblon, Le Blond. 1731 The First Tri Color Printing Process
  14. 14. 14 SOLO 1740Color History Louis Bertrand Castel (15 November 1688 – 9 January 1757) was a French mathematician born in Montpellier, and entered the order of the Jesuits in 1703. Having studied literature, he afterwards devoted himself entirely to mathematics and natural philosophy. He wrote several scientific works, that which attracted most attention at the time being his “Optique des Couleurs” (1740), or treatise on the melody of colors Louis Bertrand Castel published a criticism of Newton's spectral description of prismatic colour in which he observed that the colours of white light split by a prism depended on the distance from the prism, and that Newton was looking at a special case. It was an argument that Goethe later (1810) developed in his Theory of Colours Castel himself theorized that vibrations produced color, just as they produced sounds. He concluded, therefore, that colors and sounds were analogous, which led him to attempt to develop the “ocular harpsichord” described in this book. The harpsichord was supposed to display colors in correspondence with particular notes. He had originally meant for the harpsichord to remain theoretical, but the skepticism of his critics caused him to spend thirty years trying to construct such an instrument.
  15. 15. SOLO Color Theory 1755-Germany - Mathametician Tobias Mayer (1723- 1762) develops color theory by math, but his selection of triad colors (Red, Blue and Yellow) created . Two years later, Mayer tried to identify the exact number of colors which the eye is capable of perceiving. 1755 In 1758 — more than half a century after Newton's Opticks had appeared — the German mathematician and astronomer Tobias Mayer (1723-1762) gave a lecture to the Göttingen Academy of Science entitled "De affinitate colorum commentatio" (historical system), in which he tried to identify the exact number of colours which the eye is capable of perceiving. He chose red, yellow and blue as his basic colours, and vermillion, massicot and azurite as their representatives amongst the pigments. Black and white were considered to be the agents of light and darkness, which either lighten of darken the colours. Tobias Mayer )1723-1762(
  16. 16. 16 SOLO Color Theory 1766-England - The first known use of a color wheel was developed by Moses Harris (1731-1785), this one had Red, Yellow and Blue but he included Black as the only neutral. 1766 In 1766, one hundred years after Newton's separation of white light through a prism, a book appeared in England with the title The Natural System of Colours (historical illustration). In this work, Moses Harris (1731-1785), the English entomologist and engraver, examines the work of Isaac Newton and attempts to reveal the multitude of colours which can be created from three basic ones. As a naturalist, Harris wishes to understand the relationships between the colours, and how they are coded, and his book attempts to explain the principles, "materially, or by the painters art", by which further colours can be produced from red, yellow and blue. Harris builds upon the discovery by the Frenchman Jacques Christophe Le Blon (1667-1742). Le Bon is credited with the invention of colour printing. In 1731, during the course of his work, he observed something which every school child now learns: namely, that three paints coloured red, yellow and blue are sufficient to produce all other colours. Although Le Blon invented the fundamental three-colour palette and demonstrated his system with many dyes, he did not extend his ideas to a properly organised colour-system; that was for Harris to accomplish. Harris introduced the first printed colour-circle in 1766, specifying his primary colours very exactly: red was cinnabar, which could be made from sulphur and mercury; yellow was King's yellow (an artificial orpiment); and ultramarine was used for blue. Harris distinguished between the harmony of the "prismatic or primitive colours", which are assigned a "prismatic circle" (we show this to the left, large) and "compound colours", which are allotted their own circle (to the right, and smaller). The word "prismatic" could at first lead to confusion. In fact, Harris did not mean the spectral colours observed by Newton after light had passed through his prism and then arranged in a circle; he meant the unmixed pigments ("grand or principal colours"). A mixture ("compound") of the three basic colours will result in the three intermediate colours ("mediates") mentioned: orange, green and purple, which also appear in the prismatic circle and are all brought to life with natural descriptions ("fruit or flower"). According to Harris, the three main colours, red, yellow and blue, are: "the greatest opposites in quality to each other and naturally take their places at the greatest distance from each other in the circle". In order to arrange this "greatest distance" evenly within the circle, Harris requires an even number of circle segments (illustration), and Newton's seventh colour, indigo, is therefore dispensed with.
  17. 17. 17 SOLO Color Theory 1772 Johann Heinrich Lambert (1728-1777) Germany - Astronomer J. Heinrich Lambert (1728-1777) presented the first three-dimensional color-system In his main philosophical work, New Organon (1764), Lambert studied the rules for distinguishing subjective from objective appearances. This connects with his work in the science of optics. In 1760, he published a book on light reflection in Latin, the Photometria, in which the word albedo was introduced and the Beer– Lambert law was formulated that describes the way in which light is absorbed. Lambert also wrote a classic work on perspective and also contributed to geometrical optics. In the course of his deliberations, he consulted measurements taken by Tobias Mayer in Göttingen, and thus became aware of Mayer's colour-triangle dating from 1758, the publication of which he was to subsequently support. Lambert recognised that Mayer had discovered a means of constructing and naming many of the possible colours, and at the same time also recognised that, to extend its coverage to include their full abundance, the only element missing from this triangle was depth. After carrying out his own experiments, Lambert suggested a pyramid constructed from a series of triangles (historical illustration) to accommodate the full richness of natural colours in one geometrical form. These differ from Mayer's triangles not only in their size, but also in the position of black
  18. 18. 18 SOLO Color Theory 1772-Austria - Ignaz Schiffermüller published his color-circle in Vienna based on four colours, red, blue, green and yellow A color-circle based on four colors, red, blue, green and yellow, divided into 3 x 4 = 12 segments. His color-circle is provided with fanciful names: blue, sea-green, green, olive-green, yellow, orange- yellow, fire-red, red, crimson, violet-red, violet-blue and fire-blue. 1772 In the same year that J.H.Lambert constructed his colour pyramid and demonstrated for the first time that the complete fullness of colours can only be reproduced within a three dimensional system, another colour circle was published in Vienna by Ignaz Schiffermüller. The circumference of Schiffermüller's circle is filled with twelve colours to which he has given some very fanciful names: blue, sea-green, green, olive-green, yellow, orange-yellow, fire-red, red, crimson, violet-red, violet-blue and fire-blue. The transitions are continuous — in marked contrast to Moses Harris — and the three primary colours of blue, yellow and red are not placed at equal distances from each other; between them come three kinds of green, two kinds of orange and four variations of violet (excluding the secondary colour violet). Schiffermüller selects a total of 12 colours and thus draws upon the system originated by the French Jesuit Louis Bertrand Castel, who had published his Optique des couleurs in 1740 in order to extend Newton's circle with its seven colours up to twelve. His choice sounds unusual: bleu, celadon (pale green), vert, olive, jaune, fauve (pale red), nacarat (orange), rouge, cramoisi, violet, agathe (agate blue) and bleu violant. Castel linked his system to music — more specifically, the twelve semi-tones of the musical scale. Ignaz Schiffermüller 1726-1806
  19. 19. SOLO Color Theory 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. Goethe's color wheel from his 1810 Theory of Colours Michel Eugène Chevreul 1786 – 1889 ! Johann Wolfgang von Goethe 1749 - 1832
  20. 20. SOLO Color Theory 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. Across the same period, industrial chemistry radically expanded the color range of lightfast synthetic pigments, 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 printing became aesthetically and economically 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 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), magenta only green (+R−G+B), and yellow only blue violet (+R+G−B). It is important to add that the CMYK, or process, color printing is meant as an economical way of producing a wide 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.
  21. 21. SOLO Color Theory For much of the 19th century artistic color 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 and Josef Albers, whose writings mix speculation with an empirical or demonstration-based study of color design principles. Ogden Nicholas Rood )1831–1902( Albert Henry Munsell )1858–1918( Friedrich Wilhelm Ostwald )1853–1932( Johannes Itten (1888 --1967)
  22. 22. 22 SOLO Color Theory Flower Color Wheel
  23. 23. 23 SOLO Thomas Young 1773-1829 1807 In 1807 physicist Thomas Young’s theory that all colors can be mixed from the three basic colors of red, blue and yellow. An authority on the mechanism of vision and on optics, he stated (1807) a theory of color vision now known as the Young-Helmholtz Theory, studied the structure of the eye, and described the defect called astigmatism http://www.infoplease.com/ce6/people/A0853151.html Helmholtz later discovered that people with normal color vision need three wavelengths of light to create different colors. Helmholtz used color-matching experiments where participants would alter the amounts of three different wavelengths of light to match a test color http://psychology.about.com/od/sensationandperception/f/trichrom.htm http://physics.nad.ru/Physics/English/optics.htm Run This Color Theory
  24. 24. 24 SOLO Color Theory At the beginning of the 19th century, the Englishman James Sowerby (1757 - 1822) — already distinguished as an author of books on botany and natural history — introduced his color system, which he dedicated to "the great Isaac Newton". It had the lengthy title A New Elucidation of Colours, Original Prismatic and Material: Showing Their Concordance in the Three Primitives, Yellow, Red and Blue: and the Means of Producing, Measuring and Mixing Them: with some Observations on the Accuracy of Sir Isaac Newton. Sowerby sets himself two tasks with this work, which appeared in London in 1809: he wishes to re-emphasize the significance of brightness and darkness, which after Newton had fallen into obscurity; and he wishes to clarify the difference which exists between colors. Johann Heinrich Lambert has already emphasized that the colors of light and the colors of materials behave in a different way when mixed. In his system, Sowerby assumes the existence of three basic colors, red, yellow and blue (he actually selects gamboges — a poisonous yellow sap from Asiatic plants — carmine and Prussian blue, which are then combined). The sketches emphasize the three parts on which Sowerby's theory rests and express the stabilizing continuity which can exist between them. Incidentally, Sowerby's attempt to transform Newton's seven primary colors into three materially render able basic colors attracted the attention of the English painter William Turner (the two were, in fact, acquainted). Later, in about 1820, Turner followed the painter Otto Runge in trying to assimilate the system of the three colors red, yellow and blue into a diurnal pattern (for which there is more than just one possibility, as was soon apparent). Sowerby's text describes the optical mixtures which result when narrow and tightly packed strips of primary color are applied to paper James Sowerby )1757-1822( 1809
  25. 25. 25 SOLO Goethe’s color wheel from his 1810 Theory of Colours 1810 Johann Wolfgang von Goethe 1749 - 1832 “Theory of Colors” (original German title, Zur Farbenlehre) is a book by Johann Wolfgang von Goethe published in 1810. The work comprises three sections: i) a didactic section in which Goethe presents his own observations, ii) a polemic section in which he makes his case against Newton, and iii) an historical section. It contains some of the earliest and most accurate descriptions of phenomena such as colored shadows, refraction, and chromatic aberration. http://en.wikipedia.org/wiki/Theory_of_Colours Light spectrum, from Theory of Colors – Goethe observed that color arises at the edges, and the spectrum occurs where these colored edges overlap Color Theory
  26. 26. 26 SOLO Color Theory In 1810, the year in which Goethe's Theory of Colors with its color-circle (original drawing of Goethe) was published, the painter Philipp Otto Runge presented his work on a "color- sphere". As suggested by its title, Runge was concerned with the "construction of the proportion of all mixtures of the colors with each other, and their complete affinity" original drawing of Runge). Runge's sphere appeared in the year of his death — the painter died at the age of only thirty three. His color system, once described in an encyclopedia as "a blend of scientific- mathematical knowledge, mystical-magical combinations and symbolic interpretations", represented the sum total of his endeavors. Runge's color globe is seen as marking the temporary end to a development which had led from linear colors via the two-dimensional color-circles to a special arrangement of colors in the form of a pyramid. Philipp Otto Runge Color Sphere Philipp Otto Runge )1777–1810( 1810
  27. 27. 27 SOLO Color Theory 1839 Michel-Eugène Chevreul a chemist developed many of the laws of color harmony generally accepted today. He published his researches on color contrasts (De la loi du contraste simultané des couleurs, in 1839; the 1854 English translation is titled The Principles of Harmony and Contrast of Colors). Michel Eugène Chevreul 1786 – 1889 ! Chevreul discovered some of the problems involved with the interaction of colors on a surface. Specifically, Chevreul was concerned with the way that the depth of a black dye changed with the different colors that surrounded it. He studied this problem carefully and produced his "Law of the Simultaneous Contrast of Colors," stated as such: "In the case where the eye sees at the same time two contiguous colors, they will appear as dissimilar as possible, both in their optical composition and in the height of their tone."
  28. 28. 28 SOLO Color Theory Thomas Young (1773-1829) argued that there was a limited rather than infinite number of different retinal "particles" at every point on the retina to respond to light. He suggested that there might be three such particles only, a view later validated by science. His key contribution to color vision science may have been to restate Palmer's concept of spectral sensitivity Hermann von Helmholtz (1821-1894) championed Young's idea that retinal particles varied in the light to which they were "maximally sensitive." As a result, the trichromatic theory of colour vision also came to be known as Young-Helmholtz Theory. Influenced by his colour mixing experiments, however, Helmholtz could not accept the notion that there could be fewer than five colour primaries. Thus, he failed to accept the three retinal primaries proposed by Young. 1851 1807
  29. 29. 29 SOLO Color Theory Trichromatic 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 cone cells. The trichromatic color theory began in the 18th century, when Thomas Young proposed that color vision was a result of three different photoreceptors. Hermann von Helmholtz later expanded on Young's ideas using color-matching experiments which showed that people with normal vision needed three wavelengths to create the normal range of colors. 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 molecule called 11-cis retinal. Each different pigment is especially sensitive to a certain wavelength of light (that 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 (especially 560 nm), medium (530 nm), and short (420 nm) wavelengths respectively.
  30. 30. SOLO Theory of Colors 1859 In 1859, Maxwell, then 28 years old, presented his Theory of Color Vision, acknowledged as being the origin of quantitative color measurement (Colorimetry). In this work, Maxwell demonstrates that all colors arise from mixtures of the three spectral colors — red (R), green (here abbreviated to V [verde]), and blue (B), for example — on the assumption that the light stimulus can be both added and subtracted. He allocates each of the three main colors to a corner of a triangle, into which we have then placed a curve of spectral colors which is provided with technical data. A line of this type will reappear later in the CIE System. This is important, because all associated insights go back to Maxwell who, with his triangle, introduced the first two-dimensional color system based on psychophysical measurements. In 1849 Maxwell began his work on the subject. This work was presented to the Royal Society of Edinburgh in 1855 in his paper entitled, Experiments on Color, as perceived by the Eye, with remarks on Color-blindness. He demonstrated, using a colored top (figure 5.2.1), that any natural color could be produced from the three primary colors - red, green and blue. Most of this work was not new and merely reiterated what was already known. However it was excellently produced and was a good prelude to his later work. Maxwell's major paper in optics, On the Theory of Color Vision, was presented to the Royal Society of London in 1860 and was awarded the Rumford Medal. It showed that color blindness was due to individuals being unable to recognize red light and conclusively proved his theory of three primary colors. Most of the experiments for this work were conducted in Maxwell's London home with the help of his wife, Katherine Mary Dewar daughter of the Principle of Marchisal College, Aberdeen. These were wonderfully constructed and made use of a color box designed by Maxwell himself. James Clerk Maxwell (1831 – 1879)
  31. 31. 31 SOLO Photography 1861 James Clerk Maxwell produces the first color photograph by photographing a subject through red, yellow, and blue filters, then recombining the images. Maxwell analysis of color perception led to his invention of the trichromatic process. The trichromatic process is the basis modern color photography. http://micro.magnet.fsu.edu/optics/timeline/people/maxwell.html http://micro.magnet.fsu.edu/optics/timeline/1834-1866.html http://www.edinphoto.org.uk/1_P/1_photographers_maxwell.htm For his demonstration, he arranged for three photographs of a tartan ribbon to be taken by the professional photographer, Thomas Sutton. Each was made using a black+white slide. These slides were exposed respectively through red, green and blue filters.
  32. 32. 32 SOLO Color Theory W. Benson, “Principles of the Science of Color”, Concisely Stated To Aid and Promote Their Useful Application in the Decorative Art, London 1868; In 1868, Benson proposed the first of his many color-cubes. He considered this arrangement to be the "natural system of colors", as the title of Chapter 7 of his Principles of the Science of Color states. At the outset, Benson cited the preliminary work of Mayer, Runge and Chevreul, but then proceeds in long sentences to justify his own preference for an alternative geometry. "In order to use the normal methods of geometrical representation of all combinations which can be formed from three independent variables, a point must be chosen which represents zero or black — the absence of all light. From this point, three lines must be drawn at right angles to each other. Along these lines, and on all parallel coordinates, the colors red, green and blue shall increase in intensity, commencing at zero. The intensities of red, green and blue, which collectively give white, shall be the same, and are therefore represented by equal distancing along the three right-angled coordinates. The end points of these three lines will thus be the places for the full red, the full green and the full blue, while the lines themselves contain the shades of these three colors towards black... The corner of the cube opposite the black would be the full white, and the corners lying opposite red, green and blue would be sea-green, pink and yellow. The central point would be a medium grey." The fact that pink is given priority over purple is probably connected with its brightness. 1868
  33. 33. SOLO 1874Theory of Colors Wilhelm Max Wundt 1832--1920 Wilhem Max Wundt was a student of Helmholtz. Color space 1893 Color space 1874
  34. 34. SOLO 1876 Theory of Colors Ernst Wilhelm von Brücke (1819—1892) A change to the perception of colors under the effects of in-creased light intensity or the apparent brightness of hues changes as illumination changes. With increasing intensity, wavelengths below 500 nm shift more toward blue, and above 500 hues shift more toward yellow. Reds become yellowier with increasing brightness. Johann Friedrich Wilhelm von Bezold (1837- 1907) Bezold-Brücke Phenomenon 1874
  35. 35. 35 SOLO 1879Theory of Colors Rood was well suited to the job of bridging the gap between art and science, as he had a successful career as a teacher, scientist, and amateur painter. Rood explained many concepts that were still relatively unknown, such as the difference between additive and subtractive color mixing. He talked much about the physical color spectrum and he thoroughly described the three color making attributes of hue, saturation, and value. These three color making attributes were noticeable absent from Chevreul's work. Unlike Chevreul's book, Rood's Modern Chromatics is still considered to be scientifically accurate today. Ogden Nicholas Rood (1831–1902) was an American physicist best known for his work in color theory. He studied in Berlin and Munich before his appointment as Chair of Physics at Columbia University, a position he held from 1863 until his death. His book on color theory, Modern Chromatics, with Applications to Art and Industry, was published in 1879, with German and French translations appearing in 1880 and 1881, respectively. Rood divided color into three constants: purity, luminosity, and hue—equivalent to James Clerk Maxwell's tint, shade, and hue (Harrison, 640). Ogden Nicholas Rood )1831–1902(
  36. 36. SOLO 1883-1897Theory of Colors Alois Höfler (1853--1922) Alois Höfler (1853-1928), the Austrian educationalist and philosopher, produced many texts on both psychology and general science and made a name for himself by publishing the Berliner Kant-Ausgabe (1903). In 1897, his textbook Psychologie appeared, in which he introduced his first color system — a double pyramid with rectangular base (an octahedron). He later proposed a further, derivative color solid with a triangular base (tetrahedron). White (W.) and black (BK.) are found at the tips of both constructions, with grey appearing in the middle. Höfler also sought a relationship between the harmony of colors and music. In his books, he explicitly points to the sequence white-grey-black since he discovers here a "quasi-straight line", meaning a straight line limited at both ends. Such a line, however, appears unfamiliar to music and musical notes. The rectangle — the system of four — operates with the four elementary perceived colors: yellow (Y), red (R), blue (B) and green (G). Of these four psychological colors, only the yellow reappears, along with cyan (C) and purple (P), in the artists' triangle, which thus contains the subtractive primary colors. The purpose of Höfler's arrangement is not to provide an organisational or identification system, and neither does he consider that color variations can be subordinated, for instance to the geometrical properties of a sphere. He is more concerned with "certain alternative internal relationships" between the colors. His color-octahedron not only represents Hering's basic colors, but also their relationship as opposing colors. Höfler's solid should be seen as an expression of the relationship between colored sight on the one hand and the psychological effect of colors on the other. For this reason, many psychological textbooks have adopted his pyramids to provide information on our perception of colors.
  37. 37. SOLO 1890Theory of Colors Karl Ewald Konstantin Hering )1834–1918( Hering disagreed with the leading theory developed mostly by Thomas Young and Hermann von Helmholtz. Helmholtz's theory stated that the human eye perceived all colors in terms of three primary colors: red, green, and blue. Hering instead believed that the visual system worked based on a system of color opponency, a proposal now widely recognized as correct. Hering looked more at qualitative aspects of color and said there were six primary colors, coupled in three pairs: red-green, yellow-blue and white-black. Any receptor that was turned off by one of these colors, was excited by its coupled color. This results in six different receptors. It also explained afterimages. His theory was rehabilitated in the 1970s when Edwin Land developed the Retinex theory that stated that whereas Helmholtz's colors hold for the eye, in the brain the three colors are translated into six.
  38. 38. SOLO Color Theory The Hue is the property of light by which the color of an Object is classified as Red, Yellow or Blue in reference to the spectrum. Or as a gradation or variety of a color. Or as the Rainbow color, just like all the Hue's of the Rainbow The Hue is the term used in the world of color for the classification of Red, Yellow, Green etc. Also, although Red and Yellow are two completely different, mixing both results is Orange. ( Orange is sometimes referred to as Yellow-Red The continuum of these results in the color wheel shown as the diagram.HUE's Form a Color Wheel Albert Munsell was a art teacher and artist who published a simple color system in 1905 and an atlas of colors in 1915. His book was successful at creating a standardized set of colors that continues to be used by artists and publishers. to this day. The Munsell standardized colors make it easy for people to communicate in the language of color. Although other tools exist to define colors, most notably the CIE 1931, they are slightly more difficult to work with in comparison to the Munsell system. The simplicity of the system as helped it gain wide acceptance by artists, designers, photography, printers and more Albert Henry Munsell )1858–1918( 1905-1915
  39. 39. SOLO Color Theory 1905-1915 The three dimensions of the Munsell color system are: 1. Hue: Related to wavelength or dominant wavelength. Hue is denoted by a combination of letters and numbers making up a 100 step scale (figure 5). There are ten letter categories used to denote hue, with each of these further subdivided (by the use of numerals 1 to 10) into ten subgroups. If the numeral denoting the hue subgroup is 5, then it can be omitted (eg. 5R is the same hue as R). 2. Value: Value is specified on a numerical scale from 1 (black) to 10 (white) and this attribute is related to reflectance and luminosity (or lightness). 3. Chroma: Chroma is the Munsell term corresponding to saturation. It is indicated numerically on a scale of 0 to the various maxima dependent on the saturation obtainable with available pigments. For example, a colour may have a notation 2GY 6/10. This means it is a green/yellow that is quite close to being a yellow; it has a value of 6 (ie. almost midway in the black/white scale) and a chroma of 10 (ie. it is saturated).
  40. 40. SOLO Color Theory Albert Munsell was a art teacher and artist who published a simple color system in 1905 and an atlas of colors in 1915. His book was successful at creating a standardized set of colors that continues to be used by artists and publishers. to this day. The Munsell standardized colors make it easy for people to communicate in the language of color. Although other tools exist to define colors, most notably the CIE 1931, they are slightly more difficult to work with in comparison to the Munsell system. The simplicity of the system as helped it gain wide acceptance by artists, designers, photography, printers and more Albert Henry Munsell )1858–1918( 1905-1915 Some features of the Munsell system are used in commercially available paint and pigment mixing guides like the Color Wheel.
  41. 41. SOLO Color Theory 1914 Paul Klee (1879 – 1940) Paul Klee painted his first pure abstract, in the Style of Kairouan (1914), composed of colored rectangles and a few circles.[24] The colored rectangle became his basic building block, what some scholars associate with a musical note, which Klee combined with other colored blocks to create a color harmony analogous to a musical composition. His selection of a particular color palette emulates a musical key. Sometimes he uses complementary pairs of colors, and other times “dissonant” colors, again reflecting his connection with musicality. Klee's color theory, based on a continuous principle of movement, stands out as an individual position in the history of such theories. Starting with the six colors of the rainbow, he renders this natural phenomenon in a related circle divided into six parts. The relationship between the colors in the circle results from two different kinds of movement: a circular movement around the edge and a straight one within the diameter of the circle, which he refers to as pendular movement. From the circular form, he derives a triangle of primary colors, which he subsequently expands into an "elemental star" including the non-colors black and white.
  42. 42. SOLO Color Theory 1916 One such three-dimensional arrangement, which achieved popularity early in the twentieth century, was that devised by the Latvian-German scientist Wilhelm Ostwald (1853-1932), and first published as ‘Die Farbenfibel’ ('The Color Primer') in Leipzig in 1916. ‘Die Harmonie der Farben’ ('The Harmony of Colors') followed in 1918. Wilhelm Ostwald Color System Ostwald's color circle consists of a sequence of 24 hues divided into eight groups of three, named yellow, orange, red, purple, blue, turquoise, seagreen and leafgreen. In his lightness scale, a standard white sample (denoted a) is linked to a standard black sample (denoted p) by 13 grey steps, judged visually to be equal in interval (and lettered b to o; the sequence is usually abridged to eight steps, a, c, e, g, i, l and p). Ostwald's color wheel Wilhelm Ostwald (1853-1932),
  43. 43. SOLO Color Theory 1916 Wilhelm Ostwald Color System Ostwald's color wheel One such three-dimensional arrangement, which achieved popularity early in the twentieth century, was that devised by the Latvian-German scientist Wilhelm Ostwald (1853-1932), and first published as ‘Die Farbenfibel’ ('The Color Primer') in Leipzig in 1916. ‘Die Harmonie der Farben’ ('The Harmony of Colors') followed in 1918.
  44. 44. SOLO Color Theory 1919 Wilhelm Ostwald (1853-1932) — who came from the Baltic — received the Nobel prize for chemistry Ostwald, who had met Albert H. Munsell in 1905 on a journey to America, attempted to devise a system — just as the American painter had done — based on perception and equalising the respective differences between individual colors. Expressed in our modern technical language, we can say that Ostwald attempted to construct a perceptual color- system using non-empirical methods. In place of Munsell's three parameters, he selected an alternative group of variables: namely, color-content, white-content and black-content. He also introduced the special term "full color", by which he meant a color which permitted the sensation of one single color-tone (Munsell's "hue") and was not tempered by white or black. To be more accurate, we could say that a full color is an optimally pure color — in other words, of maximum saturation and at the same time bright. Full colors are, of course, ideal colors which cannot be reproduced by actual pigments. (When Ostwald published his Color Primer, his full colors contained about 5% white and slightly less black, as he himself admitted.) We can thus formulate the guiding principle behind Ostwald's theory of color in the following way: the most universal mixture is the mixture of full colors, white and black. Each pigmented color can be characterized by specifying the color-content (at a certain color-hue), white-content and black-content. In his Farbfibel, Ostwald proceeds systematically, drawing a distinction between chromatic and achromatic colors. He arranges his achromatic colors in the form of a grey scale along a line containing eight gradations, which conform to a geometrical sequence. In other words, the influence of visually dominant white does not decrease uniformly from above downwards, but does so geometrically, with the perceived mid-point between black and white being characterized by a proportion of approximately 20% white. (To avoid confusion, we have omitted the letters used here by Ostwald to identify these gradations.) The basis of the sequence is the so-called Weber-Fechner Law of Psychophysiology, although its application is technically limited. In fact, Ostwald abandoned his grey sequence which used this law as a basis. Friedrich Wilhelm Ostwald )1853–1932(
  45. 45. SOLO Color Theory 1917 Shinobu Ishihara (1879--1963) Shinobu Ishihara created the Ishihara Color Test to detect Color Blindness. The Ishihara Color Blindness test – named after a Japanese Professor at the University of Tokyo – is the most well known tool to test for red-green color blindness. Mr Ishihara developed this test almost 100 years ago. It was first published in 1917 and is used since then to check if someone is suffering from protanopia or deuteranopia, the two different kinds of red-green color vision deficiencies. A collection of 38 plates filled with colored dots build the base of this test. The dots are colored in different shades of a color and a number or a line is hidden inside with different shades of an other color. But enough theory, take the color blindness test by Mr Ishihara yourself and be surprised (or not) of the result. A plate from the Ishihara Test for color blindness. Can you see the number 74? However, whether you see the number or not, don’t take this as a final indication: it is only one plate of many plates in the full test and the colors on your computer screen might not be exactly right. A plate from the Ishihara Test for color blindness. Can you see the number 12?
  46. 46. SOLO Color Theory 1921 Johannes Itten (1888 --1967) Johannes Ittens color circle is based on 12 paint colors, The primary colors Red-Yellow-Blue. The secondary colors Orange-Green-Violet. The tertiary colors Yellow/Orange-Red/Orange-Red/Violet- Blue/Violet-Blue/Green-Yellow/Green. In science: Ittens names of color are not correct. From 1919 to 1922, Itten taught at the Bauhaus, developing the innovative "preliminary course"[ which was to teach students the basics of material characteristics, composition, and color. In 1920 Itten invited Paul Klee and Georg Muche to join him at the Bauhaus.[4] He also published a book, The Art of Color, which describes these ideas as a furthering of Adolf Hölzel's color wheel. Itten's so called "color sphere” went on to include 12 colors.
  47. 47. SOLO Color Theory Here is an animated RGB color cube. Notice how the colors get lighter as COLOR HAS THREE DIMENSIONS OR QUALITIES: *HUE *VALUE *INTENSITY RED YELLOW VIOLET HUE: The name given to a color. VALUE: The Lightness or Darkness of a Color + = HUE WHITE TINT + = HUE BLACK SHADE SHADE: Made by adding black to a color so that it is darker. TINT: Made by adding white to a color so that it is lighter. INTENSITY: The brightness or dullness of a color.
  48. 48. 48 SOLO Color Theory Here is an animated RGB color cube. Notice how the colors get lighter as The Color Wheel A color circle, based on red, yellow and blue, is traditional in the field of art. Sir Isaac Newton developed the first circular diagram of colors in 1666. Since then scientists and artists have studied and designed numerous variations of this concept. Differences of opinion about the validity of one format over another continue to provoke debate. In reality, any color circle or color wheel which presents a logically arranged sequence of pure hues has merit. PRIMARY COLORS Red, Yellow and Blue In traditional color theory, these are the 3 pigment colors that can not be mixed or formed by any combination of other colors. All other colors are derived from these 3 hues SECONDARY COLORS Green, Orange and Purple These are the colors formed by mixing the primary colors. TERTIARY COLORS Yellow-orange, red-orange, red-purple, blue-purple, blue-green and yellow-green. These are the colors formed by mixing a primary and a secondary color. That's why the hue is a two word name, such as blue-green, red-violet, and yellow-orange. R e d - v io le t V io le t B lu e - v io le tB lu e B lu e - g r e e n G r e e n Y e llo w - g r e e n Y e llo w Y e llo w - o r a n g e O r a n g e R e d - o r a n g e R e d R e d - v io le t V io le t B lu e - v io le tB lu e B lu e - g r e e n G r e e n Y e ll o w - g r e e n Y e ll o w Y e llo w - o r a n g e O r a n g e R e d - o r a n g e R e d R e d - v i o le t V io le t B lu e - v io le tB lu e B lu e - g r e e n G r e e n Y e llo w - g r e e n Y e llo w Y e l lo w - o r a n g e O r a n g e R e d - o r a n g e R e d
  49. 49. Color TheorySOLO 1931 CIE 1931 color space In the 1920's, W. David Wright (Wright 1928) and John Guild (Guild 1931) independently conducted a series of experiments on human sight which laid the foundation for the specification of the CIE XYZ color space. The experiments were conducted by using a circular split screen 2 degrees in size, which is the angular size of the human fovea. On one side of the field a test color was projected and on the other side, an observer-adjustable color was projected. The adjustable color was a mixture of three primary colors, each with fixed chromaticity, but with adjustable brightness. The observer would alter the brightness of each of the three primary beams until a match to the test color was observed. Not all test colors could be matched using this technique. When this was the case, a variable amount of one of the primaries could be added to the test color, and a match with the remaining two primaries was carried out with the variable color spot. For these cases, the amount of the primary added to the test color was considered to be a negative value. In this way, the entire range of human color perception could be covered. When the test colors were monochromatic, a plot could be made of the amount of each primary used as a function of the wavelength of the test color. These three functions are called the color matching functions for that particular experiment.
  50. 50. Color TheorySOLO 1931 CIE 1931 color space Although Wright and Guild's experiments were carried out using various primaries at various intensities, and a number of different observers, all of their results were summarized by the standardized CIE RGB color matching functions r (λ), g (λ) and b (λ), shown in the plot on the right (CIE 1931). Note that r (λ) and g (λ) are zero at 435.8, r (λ) and b (λ) are zero at 546.1, and g (λ) and b (λ) are zero at 700 nm. These color matching functions are the amounts of three standard monochromatic primaries needed to match the monochromatic test primary at the wavelength shown on the horizontal scale. The three monochromatic primaries are at standardized wavelengths of 700 nm (red), 546.1 nm (green) and 435.8 nm (blue). The last two wavelengths were chosen because they are easily reproducible monochromatic lines of a mercury vapor Gamut of the CIE RGB primaries and location of primaries on the CIE 1931 xy chromaticity diagram. CIE 1931 color space. The 700 nm wavelength, which in 1931 was difficult to reproduce as a monochromatic beam, was chosen because it is at the peak of the eye's red response, and therefore small errors in wavelength of this primary would have little effect on the results. The color matching functions and primaries were settled upon by a CIE special commission after considerable deliberation (Fairman 1997). The cutoffs at the short- and long-wavelength side of the diagram are chosen somewhat arbitrarily; the human eye can actually see light with wavelengths up to about 810 nm, but with a sensitivity that is many thousand times lower than for green light. These color matching functions define what is known As the "1931 CIE standard observer". Note that rather than specify the brightness o f each primary, the curves are normalized to have constant area beneath them. This area is fixed to a particular value by specifying that g (λ) = V (λ) where V(λ) is the photonic
  51. 51. Color TheorySOLO 1853 In 1853, Grassmann published a theory of how colors mix; it and its three color laws are still taught, as Grassmann's law. Grassman's work on this subject was inconsistent with that of Helmholtz. Grassmann's Law in Optics Hermann Günther Grassmann (1809–,1877) In optics, Grassmann's law is an empirical result about human color perception: that chromatic sensation can be described in terms of an effective stimulus consisting of linear combinations of different light colors. ( ) ( ) ( ) ( ) ( ) ( )∫ ∫ ∫ ∞ ∞ ∞ = = = 0 0 0 λλλ λλλ λλλ dbIB dgIG drIR Grassmann's law can be expressed in general form by stating that for a given color with a spectral power distribution I(λ) the RGB coordinates are given by: Red requires some negative values for the function
  52. 52. 52 Color TheorySOLO 1931 In the study of the perception of color, one of the first mathematically defined color spaces was the CIE 1931 XYZ color space, created by the International Commission on Illumination (CIE) in 1931 The human eye has photoreceptors (called cone cells) for medium- and high-brightness color vision, with sensitivity peaks in short (S, 420–440 nm), middle (M, 530–540 nm), and long (L, 560–580 nm) wavelengths (there is also the low-brightness monochromatic "night-vision" receptor, called rod cell, with peak sensitivity at 490-495 nm). Thus, in principle, three parameters describe a color sensation. The tristimulus values of a color are the amounts of three primary colors in a three-component additive color model needed to match that test color. The tristimulus values are most often given in the CIE 1931 color space, in which they are denoted X, Y, and Z. Any specific method for associating tristimulus values with each color is called a color space. CIE XYZ, one of many such spaces, is a commonly used standard, and serves as the basis from which many other color spaces are defined. Tristimulus values CIE 1931 color space In the CIE XYZ color space, the tristimulus values are not the S, M, and L responses of the human eye, but rather a set of tristimulus values called X, Y, and Z, which are roughly red, green and blue, respectively. (Note that the X,Y,Z values are not physically observed red, green, blue colors. Rather, they may be thought of as 'derived' parameters from the red, green, blue colors.) Two light sources, made up of different mixtures of various wavelengths, may appear to be the same color; this effect is called metamerism. Two light sources have the same apparent color to an observer when they have the same tristimulus values, no matter what spectral distributions of light were used to produce them. The CIE standard observer
  53. 53. 53 Color TheorySOLO 1931 CIE 1931 color space CIE_1931_XYZ_Color_Matching_Functions.svg )SVG file, nominally 446 × 271 pixels, file size: 54 KB( CIE1931xy_blank.svg The CIE has defined a set of three color-matching functions called , , and , which can be thought of as the CIE XYZ tristimulus values X, Y, and Z., ( ) ( ) ( ) ( ) ( ) ( )∫ ∫ ∫ ∞ ∞ ∞ = = = 0 0 0 λλλ λλλ λλλ dzIZ dyIY dxIX The tristimulus values for a color with a spectral power distribution I (λ) are given in terms of the standard observer by Color matching functions The CIE xy chromaticity diagram and the CIE xyY color space Since the human eye has three types of color sensors that respond to different ranges of wavelengths, a full plot of all visible colors is a three-dimensional figure. However, the concept of color can be divided into two parts: brightness and chromaticity. For example, the color white is a bright color, while the color grey is considered to be a less bright version of that same white. In other words, the chromaticity of white and grey are the same while their brightness differs. The CIE XYZ color space was deliberately designed so that the Y parameter was a measure of the brightness or luminance of a color. The chromaticity of a color was then specified by the two derived parameters x and y, two of the three normalized values which are functions of all three tristimulus values X, Y, and Z: ( ) ( ) ( )ZYXZz ZYXYy ZYXXx ++= ++= ++= / / / The derived color space specified by x, y, and Y is known as the CIE xyY color space and is widely used to specify colors in practice.
  54. 54. 54 Color TheorySOLO 1931 CIE 1931 color space CIE_1931_XYZ_Color_Matching_Functions.svg )SVG file, nominally 446 × 271 pixels, file size: 54 KB( The CIE has defined a set of three color-matching functions called , , and , which can be thought of as the CIE XYZ tristimulus values X, Y, and Z., ( ) ( ) ( ) ( ) ( ) ( )∫ ∫ ∫ ∞ ∞ ∞ = = = 0 0 0 λλλ λλλ λλλ dzIZ dyIY dxIX The tristimulus values for a color with a spectral power distribution I (λ) are given in terms of the standard observer by Color matching functions The CIE xy chromaticity diagram and the CIE xyY color space Since the human eye has three types of color sensors that respond to different ranges of wavelengths, a full plot of all visible colors is a three-dimensional figure. However, the concept of color can be divided into two parts: brightness and chromaticity. For example, the color white is a bright color, while the color grey is considered to be a less bright version of that same white. In other words, the chromaticity of white and grey are the same while their brightness differs. The CIE XYZ color space was deliberately designed so that the Y parameter was a measure of the brightness or luminance of a color. The chromaticity of a color was then specified by the two derived parameters x and y, two of the three normalized values which are functions of all three tristimulus values X, Y, and Z: ( ) ( ) ( )ZYXZz ZYXYy ZYXXx ++= ++= ++= / / / The derived color space specified by x, y, and Y is known as the CIE xyY color space and is widely used to specify colors in practice.
  55. 55. Color TheorySOLO 1931 CIE 1931 color space 1=++ ++= zyx ZzYyXxColor 
  56. 56. 56 Color TheorySOLO 1931 CIE 1931 color space Because three dimensional objects can’t be illustrated very well a two dimensional representation had to be found. The Y parameter of the so-called tristimulus values X, Y and Z is a measure of the brightness. This helped to easily calculate the new chromaticity values x and y by the following rules: ( ) ( ) ( ) yxZYXZz ZYXYy ZYXXx −−=++=⇒    ++= ++= 1/ / / The corresponding chromaticity diagram is shown in the right picture. The outer curved line is called spectral locus and corresponds to the well known color spectrum, shown with corresponding wavelengths. The straight line on the lower part between blue and red is called purple line. This line relates to all colors which can only be mixed up by blue and red which are not part of the color spectrum.
  57. 57. Color TheorySOLO 1931 CIE 1931 color space The new color space would be chosen to have the following desirable properties: 1. The new color matching functions were to be everywhere greater than or equal to zero. In 1931, computations were done by hand or slide rule, and the specification of positive values was a useful computational simplification. 2. The y(λ) color matching function would be exactly equal to the photopic luminous efficiency function V(λ) for the "CIE standard photopic observer" (CIE 1926). The luminance function describes the variation of perceived brightness with wavelength. The fact that the luminance function could be constructed by a linear combination of the RGB color matching functions was not guaranteed by any means but might be expected to be nearly true due to the nearlinear nature of human sight. Again, the main reason for this requirement was computational simplification. Diagram in CIE rg chromaticity space showing the construction of the triangle specifying the CIE XYZ color space. The triangle Cb-Cg-Cr is just the xy=(0,0),(0,1),(1,0) triangle in CIE xy chromaticity space. The line connecting Cb and Cr is the alychne. Notice that the spectral locus passes through rg=(0,0) at 435.8 nm, through rg=(0,1) at 546.1 nm and through rg=(1,0) at 700 nm. Also, the equal energy point (E) is at rg=xy=(1/3,1/3). 3. For the constant energy white point, it was required that x = y = z = 1/3.
  58. 58. Color TheorySOLO 1931 CIE 1931 color space The new color space would be chosen to have the following desirable properties (continue): Diagram in CIE rg chromaticity space showing the construction of the triangle specifying the CIE XYZ color space. The triangle Cb-Cg-Cr is just the xy=(0,0),(0,1),(1,0) triangle in CIE xy chromaticity space. The line connecting Cb and Cr is the alychne. Notice that the spectral locus passes through rg=(0,0) at 435.8 nm, through rg=(0,1) at 546.1 nm and through rg=(1,0) at 700 nm. Also, the equal energy point (E) is at rg=xy=(1/3,1/3). 4. By virtue of the definition of chromaticity and the requirement of positive values of x and y, it can be seen that the gamut of all colors will lie inside the triangle [1,0], [0,0], [0,1]. It was required that the gamut fill this space practically completely 5. It was found that the z (λ) color matching function could be set to zero above 650 nm while remaining within the bounds of experimental error. For computational simplicity, it was specified that this would be so.
  59. 59. Color TheorySOLO 1931 CIE 1931 color space Diagram in CIE rg chromaticity space showing the construction of the triangle specifying the CIE XYZ color space. The triangle Cb-Cg-Cr is just the xy=(0,0),(0,1),(1,0) triangle in CIE xy chromaticity space. The line connecting Cb and Cr is the alychne. Notice that the spectral locus passes through rg=(0,0) at 435.8 nm, through rg=(0,1) at 546.1 nm and through rg=(1,0) at 700 nm. Also, the equal energy point (E) is at rg=xy=(1/3,1/3). In geometrical terms, choosing the new color space amounts to choosing a new triangle in rg chromaticity space. In the figure on the right, the rg chromaticity coordinates are shown on the two axes in black, along with the gamut of the 1931 standard observer. Shown in red are the CIE xy chromaticity axes which were determined by the above requirements. The requirement that the XYZ coordinates be non-negative means that the triangle formed by Cr, Cg, Cb must encompass the entire gamut of the standard observer. The line connecting Cr and Cb is fixed by the requirement that the function be equal to the luminance function. This line is the line of zero Diagram in CIE rg chromaticity space showing the construction of the triangle specifying the CIE XYZ color space. The triangle Cb-Cg-Cr is just the xy=(0,0),(0,1),(1,0) triangle in CIE xy chromaticity space. The line connecting Cb and Cr is the alychne. Notice that the spectral locus passes through rg=(0,0) at 435.8 nm, through rg=(0,1) at 546.1 nm and through rg=(1,0) at 700 nm. Also, the equal energy point (E) is at rg=xy=(1/3,1/3). CIE 1931 color space - Wikipedia, the free encyclopedia Page 5 of 8 http://en.wikipedia.org/wiki/CIE_color_space 9/18/2006 luminance, and is called the alychne. The requirement that the function be zero below 650 nm means that the line connecting Cg and Cr must be tangent to the gamut in the region of Kr. This defines the location of point Cr. The requirement that the equal energy point be defined by x = y = 1/3 puts a restriction on the line joining Cb and Cg, and finally, the requirement that the gamut fill the space puts a second restriction on this line to be very close to the gamut in the green region, which specifies the location of Cg and Cb. The above described transformation is a linear transformation from RGB space to XYZ space.
  60. 60. Color TheorySOLO 1931 Color Blindeness, Confusion Lines and CIE 1931 color space In 1855 J. C. Maxwell said: “Find two for a colorblind undistinguishable colors. Mark them on the CIE diagram and draw a line through them. This line will connect all colors which can’t be told apart by the colorblind person. You then can find more lines and all of those lines are either parallel or meet in a single point.” A.König analyzed in 1892 the confusion lines and the so-called intersection point (also called co-punctal point) on three persons affected by color blindness. In the year 1935 F. H. G. Pitt did some further research and found the confusion lines and corresponding intersection points for protanopic and deuteranopic persons.
  61. 61. Color TheorySOLO 1931 Color Blindeness, Confusion Lines and CIE 1931 color space D. Farnsworth (1955) and L. C. Thomson & W. D. Wright (1953) completed the work by adding the results for tritanopic persons. D-15 Farnsworth
  62. 62. Color TheorySOLO 1931 Color Blindeness, Confusion Lines and CIE 1931 color space (continue – 1) Many studies followed and up to today these confusion lines are the main source while constructing tests on color blindness. If you have a look at the diagram on the right side you can see the confusion lines associated to protanopic (red-blind) persons. The colors connected by one line can’t be distinguished by a protanope. If you would draw another line through the co-punctal point (intersection point), all colors on that line would look the same to a red-blind person too. You can also see that there is a line going through a point called W. This is the so called white-point. Of course white can be told apart from red, even by a colorblind. But we have to take into account that the chromaticity diagram doesn’t include lightness. This means all colors along a line need the correct lightness adjustment to be undistinguishable by each other. Otherwise a colorblind can see a difference evenso it would be only a difference in brightness and not a different color perception.
  63. 63. Color TheorySOLO 1931 Color Blindeness, Confusion Lines and CIE 1931 color space (continue – 2) The diagram of lines for deuteranopes (green-blind) looks quite the same as for protanopes. Both types of color blindness share a strong confusion on red and green colors, therefore the name red- green color blindness The last diagram looks totally different. The shown lines are connecting undistinguishable colors for tritanopes (blue-blind). Because the intersection point is at the blue end of the color spectrum, the color perception is completely different to the ones of red- or green-blind persons. Confusion Lines – Deuteranopia Confusion Lines – Tritanopia When you have a close look at all three diagrams you can also see, that the count of confusion lines differs. This is due to the following fact: Each line shows the smallest difference between distinguishable colors. This means not only the colors on one line, but all the colors between two lines are undistinguishable by persons affected by a certain type of color blindness You can also see, that the lines are not exactly the same. Especially the intersection point is outside the range of the visible colors.
  64. 64. Color Theory Color Blindeness Normal Color Vision Red-Blind/Protanopia Green-Blind/Deuteranopia Blue-Blind/Tritanopia Blue-Weak/Tritanomaly Red-Weak/Protanomaly Green-Weak/Deuteranomaly Monochromacy/Achromatopsia Blue Cone Monochromacy SOLO
  65. 65. Color TheorySOLO Color Blindeness People with normal color vision are called “Trichomats” because they require three primates to match any arbitrary sample. The Trichromatic Eye has three cone types, each containing a photopigment which responds to a restricted range of wavelengths. There are several types of Color Deficiency due to Cone Abnormalities. In addition, the elderly see colors differently, but are not color blind in the usual sense of the term. Finally, brain damage can create a very rare condition called Achromatopsia.
  66. 66. Color TheorySOLO Color Blindeness
  67. 67. Color TheorySOLO Color Blindeness Types of colour vision deficiency Males Females Overall ~ 8 % ~ 5% Anomalous trichromasy protanomaly 1%< / FONT> 0.01% deutanomaly 5% 0.4% tritanomaly rare rare Dichromasy protanopia 1% 0.01% deuteranopia 1.5% 0.01% tritanopia 0.008% 0.008% Monochromasy rod monochromasy rare rare cone monochromasy rare rare atypical monochromasy very rare very rare Prevalence of congenital colour deficiencies
  68. 68. Color TheorySOLO Color Blindeness Anomalous Trichomats There is a subpopulation of “Trichomats”, who still requires three primaries to match a sample, but whose matches are abnormal because they use one primary far more than would be expected. While having all three cone types, one cone type is rarer, has a reduced amount of pigment, or has a pigment tuned to an unusual wavelength. The “Anomalous Trichomats” can see all Hue Categories, so they are not Color Blind in a real sense. But they may have difficulty in discriminating colors, which a Normal would easy distinguish.
  69. 69. Color TheorySOLO Color Blindeness Dichromats The second class of color abnormal is the Dichromat, a person who requires only two primaries to match any sample. These people are missing one of the three cones types. Unlike color anomalous individuals, Dichromats are true Color Blinds in the sense that there are some Hues which they cannot perceive. Lights which would appear different to a Trichromatic will appear identical to a Dichromatic, if they create the same activation ratio in their remaining Two Cone Clases. Protanopes and Deuteranopes are Red-Green Color Blind and see only Yellows and Blues. The Tritapone is analogously Blue-Yellow Color Blind. Dichromats have a Point on the Spectrum called the “Neutral Point” where the light appears achromatic. The point is about the same for both classes, 495 nm for Prontanopes and 500 nm for Deuteranopes, wavelengths which would appear slightly bluish Green to Normal.
  70. 70. Color TheorySOLO Color Blindeness Monochromats Monochromats can match any light with a single primary. They generally have no Cones and make all matches using Rods. They are very rare, 1 in 10,000,000. With only a single receptor type, they can have no Color Vision and are truly Color Blind because they distinguish only Brightness Levels. Their vision is so generally poor that the color section for visual design is the least of their problems.
  71. 71. Color TheorySOLO Generic Color Models RGB uses additive color mixing, because it describes what kind of light needs to be emitted to produce a given color. Light is added together to create form from out of the darkness. RGB stores individual values for red, green and blue. RGBA is RGB with an additional channel, alpha, to indicate transparency. Common color spaces based on the RGB model include RGB, Adobe RGB and Adobe Wide Gamut RGB. CMYK uses subtractive color mixing used in the printing process, because it describes what kind of inks need to be applied so the light reflected from the substrate and through the inks produces a given color. One starts with a white substrate (canvas, page, etc), and uses ink to subtract color from white to create an image. CMYK stores ink values for cyan, magenta, yellow and black. There are many CMYK color spaces for different sets of inks, substrates, and press characteristics (which change the dot gain or transfer function for each ink and thus change the appearance). YIQ was formerly used in NTSC (North America, Japan and elsewhere) television broadcasts for historical reasons. This system stores a luminance value with two chrominance values, corresponding approximately to the amounts of blue and red in the color. It is similar to the YUV scheme used in most video capture systems and in PAL (Australia, Europe, except France, which uses SECAM) television, except that the YIQ color space is rotated 33° with respect to the YUV color space. The YDbDr scheme used by SECAM television is rotated in another way
  72. 72. Color TheorySOLO Generic Color Models (continue) YPbPr is a scaled version of YUV. It is most commonly seen in its digital form, YCbCr, used widely in video and image compression schemes such as MPEG and JPEG xvYCC is a new international digital video color space standard published by the IEC (IEC 61966-2-4). It is based on the ITU BT.601 and BT.709 standards but extends the gamut beyond the R/G/B primaries specified in those standards. HSV (hue, saturation, value), also known as HSB (hue, saturation, brightness) is often used by artists because it is often more natural to think about a color in terms of hue and saturation than in terms of additive or subtractive color components. HSV is a transformation of an RGB color space, and its components and colorimetry are relative to the RGB color space from which it was derived. HSL (hue, saturation, lightness/luminance), also known as HLS or HSI (hue, saturation, intensity) is quite similar to HSV, with "lightness" replacing "brightness". The difference is that the brightness of a pure color is equal to the brightness of white, while the lightness of a pure color is equal to the lightness of a medium gray.
  73. 73. Color TheorySOLO Generic Color Models (Yuv) Yuv and YCrCb: Digital Video • Initially, for PAL analog video, it is now also used in CCIR 601 standard for Digital Video. • Y (luminance) is the CIE Y primary, related to R, G, B by: BGRY 11.0587.0299.0 ++= • Chrominance is defined as the difference between a color and a reference white at the same luminance. It can be represented by u and v – the color differences YRvYBu −=−= ; • YCrCb is a scaled and shifted version of Yuv and used in JPEG and MPEG (all components are positive) ( ) ( ) 5.0402.1/;5.0772.1/ +−=+−= YRCrYBCb
  74. 74. Color TheorySOLO Generic Color Models (YUV) Color Space YUV • Used for video encoding for some standards such as NTSC, PAL, SECAM. • Axes: ( ) ( ) ( ) ( )299.01/615.0 114.01/436.0 114.0587.0299.0 −−= −−= ++= YRV YBU BGRYConversion from RGB: In Matrix form                     −− −−=           B G R V U Y 10001.051499.0615.0 436.028886.014713.0 114.0587.0299.0 Y: Luma U: Blue Chroma V: Red Chroma                     −−=           V U Y B G R 003211.21 58060.039465.01 13983.101
  75. 75. Color TheorySOLO Generic Color Models Color Space YCbCr & YPbPr • Used for video encoding for digital video encoding, digital camera. • Axes: ( ) ( ) ( ) ( )YRCr YBCb GBGGRY −= −= −++−= 713.0 564.0 114.0299.0Conversion from RGB: In Matrix form                     −− −−=           B G R Cr Cb Y 081282.0418531.0499813.0 064296.0232932.0168636.0 114.0587.0299.0 Y: Luma Cb: Blue Chroma Cr: Red Chroma
  76. 76. Color TheorySOLO Generic Color Models (YIQ) Color Space YIQ • Used for video encoding for some standards such as NTSC. • Axes: • I – Q channels are rotated from the U – V channels by 33º in YUV Conversion from RGB                     − −−=           B G R Q I Y 311135.0522591.0211456.0 321263.0274453.0595716.0 114.0587.0299.0 Y: Luma I: Blue Chroma Q: Red Chroma The Y component represents the luma information, and is the only component used by black-and-white television receivers. I and Q represent the chrominance information The YIQ system is intended to take advantage of human color-response characteristics. The eye is more sensitive to changes in the orange-blue (I) range than in the purple-green range (Q) — therefore less bandwidth is required for Q than for I. Broadcast NTSC limits I to 1.3 MHz and Q to 0.4 MHz. I and Q are frequency interleaved into the 4 MHz Y signal, which keeps the bandwidth of the overall signal down to 4.2 MHz. In YUV systems, since U and V both contain information in the orange-blue range, both components must be given the same amount of bandwidth as I to achieve similar color fidelity.                     − −−=           Q I Y B G R 706.11070.11 6474.02721.01 6210.09563.01
  77. 77. Color TheorySOLO Generic Color Models (CMYK) Color Space CMYK The CMYK color model, referred to as process color or four color, is a subtractive color model, used in color printing, also used to describe the printing process itself. CMYK refers to the four inks used in most color printing: cyan, magenta, yellow, and key black. Though it varies by print house, press operator, press manufacturer and press run, ink is typically applied in the order of the abbreviation. Cyan, magenta, yellow, and key (black). Layers of simulated glass show how semi-transparent layers of color combine on paper into spectrum of CMY colors Conversion from RGB ( ) ( ) ( ) ( ) ( )YMCK CbYY CrCbYM CrYC ,,min 1287718.1255 1287142.01283441.0255 1284021.1255 = −−−= −+−+−= −−−=
  78. 78. Color TheorySOLO Generic Color Models (CMYK) Color Space CMYK CMYK refers to the four inks used in most color printing: cyan, magenta, yellow, and key black CMY(K). A subtractive color model Dye Color Absorbs Reflects Magenta Green Blue and Red Yelow Blue Red and Green Cyan Red Blue and Green Black all none
  79. 79. Color TheorySOLO Generic Color Models (HSL and HSV) HSL and HSV are two related representations of points in an RGB color model that attempt to describe perceptual color relationships more accurately than RGB, while remaining computationally simple. HSL stands for Hue, Saturation and Lightness, while HSV stands for Hue, Saturation and Value Comparison of the HSL (left) and HSV (right) color models An HSV color wheel (left) allows the user to quickly select a multitude of colors. The conical representation (right) of the HSV model is well-suited to visualizing the entire HSV color space as a single object. Notice that the triangle in the left image corresponds to one face of the cone cross section in the right image. Value is the maximum value of the R, G and B. Saturation is the difference between the maximal and minimal of the R, G and B. Hue is a function of the color of the maximal of R, G and B, adjusted by the other two.
  80. 80. Color TheorySOLO Generic Color Models (HSL and HSV) Conversion from RGB to HSL Let r, g, b ∈ [0,1] be the red, green, and blue coordinates, respectively, of a color in RGB space. max = max (r,g,b) , min = min (r,g,b) s,l ∈ [0,1] h∈ [0,360º] HSL arranged as a double-cone
  81. 81. Color TheorySOLO Generic Color Models (HSL and HSV Conversion from RGB to HSV An HSV color wheel (left) allows the user to quickly select a multitude of colors. The conical representation (right) of the HSV model is well-suited to visualizing the entire HSV color space as a single object. Notice that the triangle in the left image corresponds to one face of the cone cross section in the right image. Let r, g, b ∈ [0,1] be the red, green, and blue coordinates, respectively, of a color in RGB space. max = max (r,g,b) , min = min (r,g,b) s,v∈ [0,1] h∈ [0,360º]
  82. 82. Color TheorySOLO Generic Color Models (HSL and HSV Conversion from HSL to RGB Given a color defined by (h, s, l) values in HSL space, with h in the semi-open interval [0, 360), indicating the angle, in degrees of the hue, and with s and l in the range [0, 1], representing the saturation and lightness, respectively, a corresponding (r, g, b) triplet in RGB space, with r, g, and b also in range [0, 1], and corresponding to red, green, and blue, respectively, can be computed as follows: First, if s = 0, then the resulting color is achromatic, or gray. In this special case, r, g, and b all equal l. Note that the value of h is ignored, and may be undefined in this situation. The following procedure can be used, even when s is zero: The above operation is a modulo, so it can be simply expressed as :
  83. 83. Color TheorySOLO Generic Color Models (HSL and HSV) Conversion from HSV to RGB Given a color defined by (h, s, v) values in HSV space, with h in the semi-open interval [0, 360), and with s and v varying between 0 and 1, representing the saturation and value, respectively, a corresponding (r, g, b) triplet in RGB space can be computed: An illustration of the relationship between the “hue” of maximally saturated colors in HSV and HSL with their corresponding RGB coordinates
  84. 84. Color TheorySOLO Generic Color Models (continue) Run This The GIMP supports several methods of picking colors within the HSV color model, including the color wheel and a colored square with a hue slider GIMP (The GNU Image Manipulation Program) is a free software raster graphics editor. It is primarily employed as an image retouching and editing tool,[3] in addition to offering freeform drawing and retouching tools, GIMP can accomplish essential image workflow steps such as resizing, editing, and cropping photos, combining multiple images, and converting between different image formats. GIMP can also be used to create basic animated images in the GIF format. At present GIMP is entirely suitable for amateur or professional work with images intended for viewing on monitors and printing on inkjet printers; GIMP does not yet offer the CMYK separation and color management functionality which is essential for prepress work. Software support
  85. 85. Color TheorySOLO
  86. 86. Color TheorySOLO
  87. 87. Color TheorySOLO
  88. 88. Color TheorySOLO Since our vision system uses three different sensors to selectively detect the visual spectrum, the color space they define is inherently three dimensional. We can best visualize this three dimensional color space as a cube. One corner represents zero excitation for all three sensors or the color we call black. There is a sensor vector along each of the three edges which leave this zero excitation corner. These vectors represent the extent of the stimulus for the Rho, Gamma and Beta sensors. This cube has white at the corner directly opposite black. It has a primary color (red, green or blue) in the corner opposite its complimentary color (cyan, magenta or yellow - the secondary colors). Here is the visualization of the color space defined by the Rho, Gamma and Beta sensor stimulus vectors The RGB Color Cube
  89. 89. Color TheorySOLO There is a line connecting the black and white corners of the cube. This is the line of neutral gradient or you might think of it as the 21-step stepwedge. Neutral Gradient Line There are lines connecting each of the primary colors (RGB) with their corresponding secondary colors (CMY). These are the lines of primary-secondary gradient. These are the lines along which we make color correction judgments for prints of color images. Primary-Seconday Gradient Lines There is a triangular plane connecting each of the primary colors (RGB). Notice also that all the fully saturated colors live on the surface of the cube. Plane of the Primary Colors
  90. 90. Color TheorySOLO Each of the primary and secondary colors have their own paths from black to white. The RGB primaries move away from the black corner along three separate paths. Whenever a vector moves along a corner of the cube, it is changing in a single variable - in this case, the RGB primary itself. Once the RGB primaries reach their fully saturated corn of the cube, new vectors move diagonally across a cube side, toward the white corner. When a vector moves diagonally across a cube side, it is changing in two variables. To move from any one of the fully saturated primaries toward white, an equal amount of the other two primaries are added. For example to move from the red corner to the white corner, green and blue are added. Plane of the Secondary Colors There is also a triangular plane connecting each of the secondary colors (CMY). Notice that this plane crosses the neutral gradient line at a point closer to white than black and that the plane of the primaries crosses at a point closer to black than white. We generally expect secondary colors to reproduce lighter than primary colors in black and white images. Unlike most other visualizations of color, this one based upon sensor sensitivity vectors meets our expectation. The color cube, while perhaps a little more complex to visualize, is a very good model for gaining a better understanding of color. Primary and Secondary Gradient Vectors Secondary colors move from black to white corners in the opposite way from primary colors. The move from black to fully saturated as diagonals on a cube surface (two variable changes). In moving from fully saturated corners to the white corner, they travel along an edge (single variable change). The fully saturated outer edge of the CIE chart exists as path around the outside surface of the color cube. Edge of Saturated Hues
  91. 91. Color TheorySOLO The color cube defined by our color sensitivity vectors applies equally well to many of the systems we use to record color and to reproduce color because they are also three color systems. Below is an illustration of the 3 vector representation for an RGB value as used with 24-bit color on a computer. The RGB value of [102,140,166] represents 102/255 or 0.40 red, 140/255 or 0.55 green, and 166/255 or 0.65 blue. Three component color is easy to visualize as three vectors describing a location within the color cube. There is no equivalently intuitive description of RGB values on a CIE color chart. The cube is an over simplification, since this color space is as non linear as Einstein's warped time and space that it lives within. Still, the color cube is quite a useful first order approximation concept for understanding how we perceive color. The 216 color palette used by web browsers to down color 24-bit images for 8-bit video cards is a real world realization of this color cube and provides another good way to visualize 3 sensor color space - Web Browser Color Space.
  92. 92. Color TheorySOLO
  93. 93. Color TheorySOLO
  94. 94. Color TheorySOLO The Color Conversion Process As shown in the illustration above the colors from the original scene had to be compressed throughput the process and the number of colors available from the original to the printed image is dramatically reduced. The color conversion process that takes place within an ICC (International Color Consortium ) workflow manages this compression by re mapping colors to retain the look of the original, even though the color gamut may often be compressed or reduced. The method used to remap colors from one device to another is critical to the success of a Color Management System or CMS.
  95. 95. Color TheorySOLO The Color Calibration Process
  96. 96. Color TheorySOLO The two predominant hardware tools currently used to measure color and profile monitors, scanners, printers and even LCD projectors are Colorimeters and Spectrophotometers. A Colorimeter is a device for measuring the quality of a color by comparison with standard colors or combinations of colors. A Spectrophotometer is an instrument for measuring or comparing the intensities of the colors of the spectrum. It can be used to determine the colors of light a pigment absorbs and transmits.
  97. 97. Color TheorySOLO In general Colorimeters are used for calibrating monitors and can only record emissive light. They are much less expensive than spectrophotometers and also less accurate. Spectrophotometers on the other hand are generally much more expensive and more accurate than colorimeters. Spectrophotometers are most often used to record reflective readings from printed test targets. These targets are made up of colored patches of known values that are printed with your printer and then measured. These measurements are used to create custom profiles for a particular paper, printer and ink set. This profile characterizes the color capabilities of your printer. Colorimeters are all very similar in design and the way they function. Spectrophotometers on the other hand come in a variety of styles and prices. Some read one patch at a time, others can read strips automatically or manually and one will even read the entire target automatically. A recent product offering from GretagMacbeth, the "Eye-One" will read both emissive and reflective data. You can use this all in one device to calibrate your monitor and read reflective print targets for creating custom printer profiles.
  98. 98. 98 Color TheorySOLO
  99. 99. 99 SOLO References Color Theory Wyszecki, G., Stiles, W.,S., “Color Science – Concepts and Methods, Quantitative Data and Formulas”, John Wiley & Sons, 1967 Rodney, A., “Color Management for Photographers – Hands on Techniques for Photoshops Users”, Elsevier, 2005 ASTR 511, Majewski, Lecture Notes (Fall 2005) Gal Ben-David, “Video Engineering Course”, October 2009 Westland, S., Ripamonti., C.,“Computational Color Science Using Matlab”, John Wiley & Sons, 2004 White, R., “How Digital Photography Works”, Que, 2nd Edition, 2007 Jacobson,R.,E., Ray, S.,F., Attridge, G.,G., Axford, N.,R., “The Manual of Photography – Photographic and Digital Imaging”, Focal Press, 9th Edition, 2000 Morović, J., “Color Gamut Mapping”, John Wiley & Sons, 2008
  100. 100. 100 SOLO References (continue - 1) Color Theory http://www.nndb.com/people/016/000095728/ http://en.wikipedia.org/wiki/Johann_Heinrich_Lambert http://en.wikipedia.org/wiki/Ignaz_Schifferm%C3%BCller http://en.wikipedia.org/wiki/Louis_Bertrand_Castel http://www.medienkunstnetz.de/artist/louis-bertrand-castel/biography http://www-history.mcs.st-and.ac.uk/~history/Biographies/Castel.html http://www.lib.udel.edu/ud/spec/exhibits/recent/science.html http://www.amastro2.org/at/ot/othcs.html http://home.wanadoo.nl/paulschils/05.00.html http://www.colorsystem.com/projekte/engl http://www.handprint.com/HP/WCL/color6.html http://www.coloryourcarpet.com/History/ColorHistory.html http://home.wanadoo.nl/paulschils/08.00.html
  101. 101. 101 SOLO References (continue - 2) Color Theory http://www-history.mcs.st-and.ac.uk/Projects/Johnson/Chapters/Ch4_2.html http://en.wikipedia.org/wiki/Color_photography http://en.wikipedia.org/wiki/Color_theory http://www.infoplease.com/ce6/people/A0853151.html http://physics.nad.ru/Physics/English/optics.htm http://psychology.about.com/od/sensationandperception/f/trichrom.ht mhttp://en.wikipedia.org/wiki/Theory_of_Colours http://en.wikipedia.org/wiki/Michel_Eug%C3%A8ne_Chevreul http://www.brown.edu/Courses/CG11/2005/Group161/ColorTheory.htm http://en.wikipedia.org/wiki/Ogden_Rood http://en.wikipedia.org/wiki/Ewald_Hering http://en.wikipedia.org/wiki/Albert_Henry_Munsell httphttp://www.danielgmurphy.com/physics/4_color/d_color_models.html
  102. 102. 102 SOLO References (continue - 3) Color Theory http://www.bauhaus.de/english/bauhaus1919/unterricht/unterricht_klee.htm http://en.wikipedia.org/wiki/Paul_Klee http://en.wikipedia.org/wiki/Wilhelm_Ostwald http://www.coloracademy.co.uk/ColorAcademy%202006/subjects/ostwald/ostwald.htm http://www.colblindor.com/2006/03/15/color-blindness-test-by-dr-shinobu-ishihara/ http://www.colorbasics.com/Munsell/ http://www.colourmed.com/tests.html http://www.colormatters.com/colortheory.html http://www.optics.arizona.edu/opti588/reading/CIE_color_space.pdf http://www.fho-emden.de/~hoffmann/ciexyz29082000.pdf http://en.wikipedia.org/wiki/CIE_1931 http://en.wikipedia.org/wiki/Grassmann's_law_(optics) http://en.wikipedia.org/wiki/Hermann_Grassmann http://webvision.med.utah.edu/ http://www.colblindor.com/coblis-color-blindness-simulator/ http://en.wikipedia.org/wiki/Color_space
  103. 103. 103 SOLO References (continue - 4) Color Theory http://en.wikipedia.org/wiki/YUV http://en.wikipedia.org/wiki/YIQ http://en.wikipedia.org/wiki/HSL_and_HSV http://en.wikipedia.org/wiki/GIMP http://dx.sheridan.com/advisor/cmyk_color.html http://photo.net/learn/optics/edscott/vis00020.htm http://hyperphysics.phy-astr.gsu.edu/hbase/vision/colmeascon.html#c1 http://www.booksmartstudio.com/color_tutorial/colortools.html
  104. 104. January 5, 2015 104 SOLO Technion Israeli Institute of Technology 1964 – 1968 BSc EE 1968 – 1971 MSc EE Israeli Air Force 1970 – 1974 RAFAEL Israeli Armament Development Authority 1974 – 2013 Stanford University 1983 – 1986 PhD AA

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