Take a break:Watch some stop-motion animationMusic: Grindin’http://vimeo.com/962537012skip chap. 8 for nowChap. 9 – Color (continued)Lecture 18Thursday, March 11Next week: Chapter 10, start reading.March 30: exam reviewApril 1: exam II BA3Ch. 9 - Color• Spectral and non-spectral colors• Intensity distribution curve• Intensity, hue, saturation• Additive primaries: R, G. B.• Subtractive primaries: C, M, Y• Hair, skin, and eye color• CIE diagram• Lighting, painting and printingWe are here4Color in plants and animals Chlorophyll reflects green and absorbs red and blue. The reflected green is not being used. So it is clear that green is NOT the best color of light for growing plants.Carotenoidsare a class of compounds that color carrots, tomatoes, corn, and peppers. Some animals absorb this coloring from plantsand become orange themselves, such as lobsters and flamingos. Autumn colorsoccur when the chlorophyll decays leaving behind the more brightly colored carotenoids. Anthocyaninis another plant color that is often magenta, containing both red and blue. For example, eggplants, some cabbages, and berries contain anthocyanin.Myoglobin, a compound that stores oxygen, is in red meat. "Dark meat" such as chicken legs or hearts, contains more myoglobin. These muscles are used constantly. The breast muscle of chicken is rarely used for flying, and thus is lighter, containing less myoglobin.5Hair, skin, and eye color1. Your pigment is melanin. You have 2 formspheomelanin (yellow/red)eumelanin (black and brown subtypes)Albino persons = no pigment at allThere are additional genes (more than one) affecting how much wehave of each kind.2. The signaling genehas 300 amino acids in the DNA sequence. There are many variations.Variations produce red hair, blonde, auburn, strawberry blonde, etc. 6Skin color and evolutionSunlight creates vitamin D. Europe = less sunlight = less vitamin D Light skin (less melanin) is an advantage. Other chemicals (folate) are broken down by sunlight. Equator = more sunlight = more folate loss Dark is an advantage. (Skin cancer occurs to late in life to affect survival.)Ability to tan: Is also inherited. Red haired people do not tan.7Eye colorSmall amount of pigment = blue eyes. Tiny particles (cells) in the eye scatter blue better, like the atoms that scatter blue light from the sky or from the swimming pool.Pigment hides the blue. More eumelanin pigment = brown eyes. Less brown pigment = hazel, green, etc. 8Hair color• Eumalinin colors hair brown or black. • Pheomelanin colors hair red in small quantities, black in large quantities. And makes freckles.• Low amounts of either results in blonde or strawberry blonde. • Gray occurs with aging as melanin production stops in the hair follicle.9Ch. 9 - Color• Spectral and non-spectral colors• Intensity distribution curve• Intensity, hue, saturation• Additive primaries: R, G. B.• Subtractive primaries: C, M, Y• Hair, skin, and eye color• CIE diagram• Lighting, painting and printingWe are here10CIE diagram(International Commission on Illumination)This is a color triangle with Green at the top, Blue at lower left, Red at (lower) right “x,y” positions on the color triangle represent all the colors that can be reproduced by adding red, green and blue. Limitation: darkness is missing. To be complete you must also specify lightness or brightness.11White: X = 1/3Y = 1/3Spectral colorwavelengths areat the left and right edgesLess saturated colors are near the centerNon spectral colors are at this edge12Projection (additive) TV systems can only reproduce colors insidethe triangle between the 3 colors of the sources (dots).13Comparison of old TV phosphors with LEDs (light emitting diodes)14Properties of the CIE diagramThe spectral colors are on the left and right edgesEqual mixing of two spectral colors on the edge makes the color half way between these two colors (on the line joining the two colors.) Where is magenta on the diagram? It is half way across the bottom, which is an equal mixture of red and blue.What’s greatabout this diagram: two numbers, x and y, can be used to describe a color.What’s missing from the C.I.E. diagram?Because the colors are adjusted to add to 100%, dark colors (that total less than 100%) aren’t represented, for example, black and brown.15Alterbate diagram: Munsell’s color tree: Hue, value and chromaan alternate way to indicate color that includes brightnessCompare to: 16Ink transmission curves400 nm 500 nm 600 nm 700 nm100%Magenta = white – green17Ink transmission curves400 nm 500 nm 600 nm 700 nm100%Cyan = white – red 18Ink transmission curves400 nm 500 nm 600 nm 700 nm100%Yellow ink (unsaturated) = white – blue(contains green, yellow, orange and red)19Additive and subtractive color mixingWhy does one figure have a black background and the other is white?20Concept Question:Cheat sheet21Concept Question:Cheat sheetConcept Question:Cheat sheetConcept Question:Cheat sheetConcept Question:Cheat sheetConcept Question:White is an equal mixture of red, green and blue. What is another metamer for white light?A. Red and cyan;B. Cyan, magenta and yellow;C. Blue and yellow;D. A,B, and CNo cheat sheet26Ch. 9 - Color• Spectral and non-spectral colors• Intensity distribution curve• Intensity, hue, saturation• Additive primaries: R, G. B.• Subtractive primaries: C, M, Y• Hair, skin, and eye color• CIE diagram• Lighting, painting and printingWe are here27Methods of adding colors1. Addition of illumination: stage lighting and 3-color TV projector. Projected colors overlap.2. Partitive mixing: closely spaced dots of colors. TVscreens, laptop screens, pointillist paintings, tight textile weaves, some printing3. Time mixing:a rotating color wheel. It’s hard to find examples.4. Binocular mixing: different color to each eye. The colors "blend" in the brain. 28Partitive mixingis placing colors next to one another so that they are merged in the eye.Examples: Pointillist paintingLCD screensOld TV screens (CRT)Plasma TVsDetail from Circus Sideshow (or Parade de Cirque) (1889) showing pointillism Georges Seurat29Georges Seurat, Sunday Afternoon on the Island of La Grande Jatte, 1884-1886, The Art Institute of Chicago. 30Sources of light, color balanceColor balance important for movies and stage lighting.White light should contain equal amounts R, G and B but often does not.Examples of odd (unbalanced) lighting:Candles and campfires contain an excess