Chapter 6


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Chapter 6

  1. 1. Understanding Color Chapter 6: Illusion and Impression
  2. 2. An optical illusion is a purely visualexperience that is mistaken for an objective reality.
  3. 3. The simplest illusions are caused by involuntary responses of the eyes tooverstimulation by something specific, like a single hue or extreme contrast.
  4. 4. Current thinking is that all illusions have aphysiological basis and are caused by a disturbance to the flowof information betweenthe eyes and the brain.
  5. 5. Opticalillusions alsodepend on thearrangementof designelements:forms, lines,and colors.
  6. 6. Color illusions occur when colors thathave specificrelationshipsare arranged in ways that mislead the eyes.
  7. 7. Technology like holography make the illusion of depth possible.
  8. 8. But impressions or representations of depth on a screen or page are not actual illusions.
  9. 9. They are actually only drawing conventions called pictorial depth cues like: overlapping,
  10. 10. linear perspective,
  11. 11. shading and shadow,
  12. 12. texture gradients,
  13. 13. and atmospheric perspective.
  14. 14. Of these pictorial depth cues, only atmospheric (or arial) perspective has a hue component.
  15. 15. Objects farther away appear less distinct, lighter, and bluer.
  16. 16. Remember that the more pictorial depth cues in an image, the more likely it is to be perceived as representing depth.
  17. 17. Motion parallax is a real-world depth cue that includes motion and time.
  18. 18. Motion parallax can only take place on a screen (or in real time!)
  19. 19. The most convincing illusions of depth result when a full array of depth cues is reinforced by thespatial effects of colors.
  20. 20. One way to characterize thenature of colors is to think of them in terms of “near” or “far.”
  21. 21. Some colors have inherent qualities of “nearness” or “farness.”Light blues seem to move away and warm colors of any value close in.
  22. 22. But in color compositions, the hue, value, andsaturation of each form in relation to its ground or surrounding colors influence whether it is perceived as advancing or receding in space.
  23. 23. In general...
  24. 24. Hue:Warm huesadvancerelative tocooler ones.
  25. 25. Saturation:Brilliant colors(saturatedcolors andstrong tints)appear to comeforward relativeto muted colorsor grays.
  26. 26. Value:In a simple image of a figure against a ground, the figure will advance no matter whether it is lighter or darker than its background.
  27. 27. This interpretation of “near and far” is an aspect of visual processing called figure-ground perception.
  28. 28. The brain sorts visualinformation into darkand light areas anddetermines theiredges, then translatesthis into adetermination of whichpart of the image isfigure and which isbackground.
  29. 29. A dark figure comes forward on a light ground.A light figure comes forward on a dark ground.
  30. 30. When figures of different value are laid against the same ground, the difference between each in relation to the ground determines which will advance and which will recede.
  31. 31. The figure that is MOST DIFFERENT from the ground will seem to advance the most.
  32. 32. The greater the value contrast with the ground, the more a figure will advance.
  33. 33. This is one of the reasons why atmospheric perspective is so powerful.
  34. 34. Which figure advances and why?
  35. 35. Dark or light color also influences how the size of a figure is perceived.
  36. 36. Lighter colored figures appear larger than dark ones.
  37. 37. (This is why women love to wear black!)
  38. 38. Color alone doesnot create an effectof depth. It is asecondary indicatorthat supports oneor more pictorialdepth cues. Thespatial effects ofcolors can bereduced orreversed bypictorial depthcues.
  39. 39. In this example, thefigure-groundperception trumpsany spatial effectsof the colors.
  40. 40. In this painting by Gauguin, the hot colors in the backgroundadvance, and the cooler colors in the front recede, but spatial order is maintained by overlap and figure-ground clues. The space, however, does seem shallower due to the color arrangement.
  41. 41. The key to predicting when a color will advance or recede lies in the phrase “all other factors being equal.” The dominant quality of a color determines whether it seems to move forward or backward.
  42. 42. A transparence illusion is a three-dimensional illusion that takes place when two opaque colors and an interval between them are arranged in such a way that one color appears to betransparent and lying on top of another.
  43. 43. A transparence illusion depends equally on two ideas: • the pictorial depth cue of overlap • the intervals of a parent-descendant color series
  44. 44. The guidelines of spatial effects determine which color in a transparence illusion will appear to be on top of the other.
  45. 45. A color that is high in value, warm, or brilliant will appear to be on top when paired with a darker, cooler or duller one.
  46. 46. If the middle color isan interval betweenwarm and coolparents, the warmerparent color appearsto be on top.
  47. 47. If the middle color isan interval of valuebetween the parentcolors, the lighterparent color appearsto be on top.
  48. 48. If the middle color isan interval betweenchromatic andachromatic parents,the chromatic parentwill appear to be ontop.
  49. 49. Shifting the middle interval closer to one parent orother alters the apparent degree of transparency of the top color.
  50. 50. Certain hues suggest transparency. Cool hues, especially tints of blue and green, often seem transparent.
  51. 51. Hues that areboth warm anddark seem moredense andopaque.
  52. 52. And the mediummakes adifference.Brilliance andtransparency aremore easilydisplayed on ascreen...
  53. 53. ...and opacity isshown moreconvincingly onpaper.
  54. 54. Fluting is an illusionthat occurs in a series of uniform vertical stripes with progressive steps of value.
  55. 55. This is because of thesimultaneous contrast between different values.
  56. 56. You always see a darker line on the darker side and alighter line where thelighter value touches the darker.
  57. 57. This does not occur when colors are arranged in a random order.
  58. 58. Vibration is an effectthat takes place when blocks of brilliant and complementary (or near-complementary) colors that are close in value are placed together.
  59. 59. Vibration is caused by several things: theinability to find edges, the conflict of trying to reach equilibrium in opposing and brilliant colors at the same time, and the effect of natural eye movements called saccades.
  60. 60. Saccade is pronounced “sa-Kahd”
  61. 61. Saccade is pronounced “sa-Kahd” They are involuntary eye movements thatoccur constantly and rapidly, but we are not at all aware of them.
  62. 62. The effect can be eliminated by separating the colors so that they no longer touch.
  63. 63. Vanishing boundaries occur whenareas of similar hue and close value areplaced next to (or on top of) one another.
  64. 64. Vanishing boundaries arenot uncomfortable in the same way as vibration.
  65. 65. The eyes do not need to seek equilibrium in two different ways at the same time.
  66. 66. The illusion ofluminosityoccurs in part asthe result of theinability to findedges.
  67. 67. Effects ofluminosity followthe guidelines ofspatial effects:lighter colorsmove forwardrelative to dark...
  68. 68. ...and more vivid colors move forward relative to dull ones.
  69. 69. Softer, glowinglight isachieved bybarelydiscernibleprogressivevalue intervalsfrom light todark.
  70. 70. When the halo is a series of intervals justat the threshold of vision, the effect is of a shimmering light source.
  71. 71. (You also see how lighter values move forward in this figure.)
  72. 72. Dark and light areas arranged in this way illustrate glowing light, but a brilliant hue arranged in the same way has a much more dramatic impact.
  73. 73. Remember that we are talking about the“impression” of light in subtractive color. Additive light actually glows.
  74. 74. The Bezold effect, or spreading effect, describes what happens when the value of an entire composition isaltered by adding, removing, or changing one color only.
  75. 75. Unlike most illusions and special effects it is an effect of line.
  76. 76. It takes place when internal design elements are outlined, or separated from the ground by dark or light line.
  77. 77. When the forms are enclosed by a light line, all colors appear lighter, and vice versa.
  78. 78. The presence of a darkor light outline changes only the perception of the overall value of a composition.
  79. 79. Hue andsaturation are not affected.
  80. 80. Because every image is created by the placementof different values, changing a block of color from dark to light creates a new and different image – not a lighter or darker version of the original.
  81. 81. An optical mix, (or partitive color,) is created when two or more colors, in tiny masses or patches just at thethreshold of vision, are used together to create a wholly new color.
  82. 82. The color masses inan optical mix are sotightly configuredthat they are verydifficult to distinguishas individualelements, but the donot entirely blend.
  83. 83. Optical mixes are sometimes called retinal mixesbecause color is mixed in the eyes, not in a jar or on a palette. La Grande Jatte, Georges Seurat, 1884
  84. 84. The success of an optical mix depends on the size of its color masses relative to the distance from which the whole will be ordinarily seen.
  85. 85. The size of the color masses or patches dependstotally on the distance from which the work will be viewed.
  86. 86. Optical mixes that are below the thresholdof vision play an enormous role in industry and design.
  87. 87. Most color printing is achieved by the optical mixing of process colors.
  88. 88. Even your computer screen is really using opticalmixing with the millions of red, green and blue pixels that make up all colors seen.
  89. 89. The End