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Digital Media

Digital Media. Lecture 7: Color part 2 Georgia Gwinnett College School of Science and Technology Dr. Jim Rowan. Refer to Supplemental text:. g. y. r. w. c. m. b. You have a blue ball and walk into a room lit with a red light. What color is the ball while in the room?.

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Digital Media

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  1. Digital Media Lecture 7: Color part 2 Georgia Gwinnett College School of Science and Technology Dr. Jim Rowan

  2. Refer to Supplemental text:

  3. g y r w c m b • You have a blue ball and walk into a room lit with a red light. What color is the ball while in the room?

  4. Color Models other than RGB • CMYK • cyan • magenta • yellow • key (black) • HSV, HSB, HSL • Hue • Saturation • value. brightness, lightness

  5. g y r w c m b • Colored light shining on a white surface • One red light, one blue light and one green light… • Arranged to overlap… • Creating Cyan, Magenta and Yellow and… • White

  6. g y r w c m b Yellow = Red + Green Yellow = White - Blue Cyan = Green + Blue Cyan = White - Red White = Red + Green + Blue Magenta = Red + Blue Magenta = White - Green This color model can be used as an Additive model appropriate for use with light This color model can also be used as a Subtractive model appropriate for use with ink and paint... things that absorb light

  7. leaving magenta light leaving leaving leaving magenta light cyan blue light light removes green removes green removes red white light removes red white light white light magenta ink white paper cyan ink white paper

  8. CMYK model • Cyan • Magenta • Yellow • Key (black) • While you should be able to make black by mixing Cyan, Magenta and Yellow… • Paint (and ink) is not perfect • Subtractive model • Used by the printing industry

  9. HSV model • Another way of looking at color • Hue • The color described as degrees from red • Saturation • How pale the color is • Think of it as adding white to the color • Brightness • How intense the color is • Thinks of it as adding black to the color

  10. Adjusting the Hue

  11. Adjusting the Hue

  12. Adjusting the Hue

  13. Adjusting the Hue

  14. Adjusting the Saturation

  15. Adjusting the Value

  16. Full-On Red in RGB model

  17. Full-On Green in RGB model

  18. Full-On Blue in RGB model

  19. The transition from B&W to Color TV • B&W just needs intensity changes to make white-gray-black • intensity varies as the electron beam is drawn across the screen • Color is RGB+Intensity for each • could transmit each color with its intensity and it would work for color tv but • can’t use the same signal model for color because the B&W tv’s wouldn’t work • Solution: Transmit the necessary color information during the retrace. • Color is transmitted as luminance and two colors • B&W tv’s simply ignore it because the beam is off

  20. RGB Channels • Allows the use of the brightness and contrast of each individual color to be manipulated using levels and curves • Allows a very fine level of control • Very time consuming • Color balance, hue and saturation adjustments on the whole image is a shortcut

  21. Channels Red Green Blue http://en.wikipedia.org/wiki/Channel_(digital_image)

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