11End Chap. 7 – Visual perceptionskip ch. 8 for nowBegin Chap. 9 - ColorLecture 17Tuesday, March 9Finish reading Chapter 9Next week: Chapter 10March 30: exam review; April 1: exam II 2timeFlash of lightTemporal response of the eyeEnd of Chap. 723Watching a movietimeOverlap in time4Motion effects from Michael Bach’s web page• Silhouette illusion• Motion induced blindness• Motion aftereffect (Waterfall illusion)• Spiral aftereffect (motion channel activated)• Breathing squarehttp://www.michaelbach.de/ot/index.html35Review – time effects• Fatigue• Involuntary eye movement• Successive lightness contrast• Positive and negative afterimage• Fading• Latency and persistence 6Ch. 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 here47Spectral colors8Spectral colorsCorrespond to a particular wavelength• red 650 nm additive primary color• orange• yellow • green 530 nm additive primary color• blue 460 nm additive primary color• (indigo)• violet 400 nmMnemonic: Roy G. Biv59Additive primaries (more later)•Red• Green •BlueRed + Blue + Green = White All colors can be made by projecting these onto a screen so that the light is added. 10Colored light may originate several ways:• A red light emitsonly red light. • A red paint reflectsonly red light. Other wavelengths are absorbed. • A red filter transmitsonly red light.Other wavelengths are absorbed.61111Spectral curve shows the relative amount of each wavelength emitted1212Transmission curve shows the relative amount of each wavelength transmittedTransmission of a red filter 400 nm 500 nm 600 nm 700 nm100%713Non-spectral colors are mixtures • Brown = red + green• Turquoise = blue + green• Silver (shiny gray)• Pink = blue + red + white•Gold•Plum•Tan• White (red + blue + green)?14Spectral curves for nonspectral colorsCurves for cyan and magenta include multiple colors. 400 nm 500 nm 600 nm 700 nm100%815Cyan and magenta are most important nonspectral colors Cyan = blue + green Magenta = red + blue 16Ch. 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 here917How would you “text” someone a color, accuratelyTell them: Intensity, hue, saturationIntensitylightness (a source) or brightness (a surface)Hue: dominant wavelength red, or 650 nmSaturationpurity, is the spectral color narrow (pure color) or broad so that neighboring colors are included 18Saturation• A saturated red is a narrow band of wavelengths• An unsaturatedred is a broad band of wavelengths400 nm 500 nm 600 nm 700 nm100%saturated redunsaturatedred1019Mixing light: additive primariesThe eye averages nearby colors to a central value of wavelength that appears to be a spectral color. Yellow + red = orangeOr, it could be a nonspectral color:Blue + green = cyan, turquoise, teal The eye averages “distant” colors to something nonspectral. Red + blue = magentaRed + green = brown 20Artists’ primariesArtists’ primaries are blue, yellow, and red. This is a different nomenclature from what is used in this course.1121Wikipedia22What color does this spectral curve look like? 400 nm 500 nm 600 nm 700 nm100%1223What color does this spectral curve look like? 400 nm 500 nm 600 nm 700 nm100%Answer: Yellow, although there is no yellow light 24What color does this spectral curve look like? 400 nm 500 nm 600 nm 700 nm100%1325What color does this spectral curve look like? 400 nm 500 nm 600 nm 700 nm100%Answer: White26What color does this spectral curve look like? 400 nm 500 nm 600 nm 700 nm100%1427What color does this spectral curve look like? 400 nm 500 nm 600 nm 700 nm100%Answer: Gray 28Gray filters, some mathA gray filter cuts down the amount of light equally for all colors (wavelengths). Two filters passing 50% placed together pass 25%. Why? 50% of 100% is 50%, and this comes through the first filter. 50% of 50% comes through the second filter, and 0.5 x 0.5 = 0.25, and 0.25 of something is 25% if it.1529What color does this spectral curve look like? 400 nm 500 nm 600 nm 700 nm100%30What color does this spectral curve look like? 400 nm 500 nm 600 nm 700 nm100%gray + red = pink1631MetamersLook the same but have different curves 400 nm 500 nm 600 nm 700 nm100%400 nm 500 nm 600 nm 700 nm100%Two ways to see yellow. 32Complementary colorsThe complement is the color you would add to get white. If R + G + B = White, thenComplement of Red = G + B = cyan Complement of Green = ?1733Complementary colorsComplement of Blue = R + G = YellowYellow + Blue = White 34Ch. 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 here1835Subtractive primariesare the complements of the additive primariesYellowBlueMagentaGreen CyanRedSubtractive primaryAdditive primaryAll colors can be projected using 3 lights of additive primary color, OR 3 subtractive primary inks. 36What are the colors shown on this package?1937Ink transmission curves400 nm 500 nm 600 nm 700 nm100%Magenta = white – green 38Ink transmission curves400 nm 500 nm 600 nm 700 nm100%Cyan = white – red2039How inks make all colorsNo ink = paper = white = R + G + B• Cyan ink + Magenta ink = ?(blocks red) + (blocks green) → blue• Cyan ink + Yellow ink = ? (blocks red) + (blocks blue) → green• Magenta ink + Yellow ink = ? (blocks green) + (blocks blue) →
View Full Document