11End Chap. 7 – Visual perceptionskip ch. 8 for nowBegin Chap. 9 – Color (Read Ch. 9)Lecture 18Thursday, Oct. 21Nov.2 : exam review; Nov. 4: exam II We went through all these viewgraphs. 2Lecture plan2Exam II, Nov. 4, will cover • Ch. 4 (camera), • Ch. 5 (the eye), • Ch. 6 (optical instruments), • Ch. 7 (visual perception),• Ch. 9 & 10 (color & color perception). •We save Ch. 8 for later. We are here23timeFlash of lightTemporal response of the eyeEnd of Chap. 74Watching a movietimeOverlap in time1/24 secondTV scan rate is 60 per second35Review – 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 surface) or brightness (sources) 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?CMY print cartridge1937Ink 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) → red40Take a break:Watch some stop-motion animationMusic: Grindin’http://vimeo.com/962537040214141Ch. 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 here4242Color 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