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Principles of Color Television

Principles of Color Television. Three Basic Colors of Television. Blue Red Green. 59 %. 11 %. 30%. Three Color Characteristics. Hue – adjusted color sometime called tint control (from green to red)

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Principles of Color Television

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  1. Principles of Color Television

  2. Three Basic Colors of Television • Blue • Red • Green 59 % 11 % 30%

  3. Three Color Characteristics • Hue – adjusted color sometime called tint control (from green to red) • Brightness – illumination of the picture that includes sharpness of edges including the contrast control • Saturation -

  4. Lights • 430 Terahertz (430 X 10 Hz) to 750 Terahertz (750 X 10 Hz) • 430 Terahertz is considered as a wavelength • 750 Terahertz correspond to the color red and the higher frequency • 400 nm seen deep blue • Some colors do not correspond to any one given wavelength of light (example brown and purple) 12 12

  5. Electromagnetic Spectrum

  6. Color Mixing • When sunlight passes through a glass prism will separate into multitude of color components. The display is called saturation

  7. Subtractive color mixing • Subtractive mixing – make use of filtering action that dyes pigments and inks. Ex: pictures, photographs, color movies. • Additive mixing – superior to subtractive mixing. Using the primary colors as the base.

  8. Spectrum of White light

  9. Additive Mixing

  10. Result of Additive Mixing

  11. Result of 3 color additive mixing 50% Saturated Yellow 50 % Saturated red 100% White 50% White White Gray pink Pale yellow Pale green Bluish Green

  12. Luminance Level • Dark yellow producing a shade of gray approaching black • Y= 0.59G + 0.39R + 0.11B • For equal Energy • Y = 0.59(1) + 0.30(1) + 0.11(1) • =1.00 • For 50 % red 100% blue 100% green • Y = 0.59G + 0.30R + 0.11B • = 0.59(1) + 0.30(1) + 0.11(1) • = 0.59 + 0.15 + 0.11 • =0.85

  13. Object size and color • A 23 in television picture tube can show a video signal of 0.5 MHz or less correspond to horizontal picture tube object sizer ranging from 0.34 in or more. • Object sizes ranging from 0.34 in to a minimum of 0.12 in corresponding to the half cycle of video frequency of 1.5 MHz. • Only two colors orange and cyan can provide complete color reprodution

  14. continuation • Luminance signal information has required bandpass from 0 to 4.2 MHZ • The narrower the bandwidth of the color information the less complex the color tv system need be.

  15. Color Television Transmission

  16. Matrix Y Color Transmitter

  17. G-Y Matrix • (R –Y) + Y = R • (B – Y) +Y = B • (G – Y) + Y = G

  18. Y color Receiver

  19. Balance Modulator

  20. Color Burst color synchronizing

  21. Phase relationship • The amplitude of the composite chrominance signal represents the color Saturation information and its phase corresponds to the actual color of hue information of the picture being transmitted • Phasor – a sine and cosine waves can be represented by a straight line.

  22. Three phasors properties • Length • Speed of counter clockwise rotation • Relative angular position

  23. Performance of the chrominance signal • Y =0.59G + 0.30R + 0.11B =0.599(0) +0.30(0) + 0.11(0) = 0.41 • R –Y = 0.70R – 0.11B– 0.59G =0.70(1) – 0.11(1) – 0.59(1) = 0.59 • B – Y 0.89B – 0.30R – 0.59G =0.89(1) – 0.30(1) – 0.59(0) = 0.59

  24. COLOR PHASE ANGLE

  25. Misconvergence

  26. Low green adjustment

  27. High adjustment of blue

  28. Dominant Red missing green

  29. Dominant Blue Missing Green

  30. Missing Red

  31. Too much Blue adjustment

  32. Low red adjustment

  33. Low green and blue adjustment

  34. Low red and green color adjustment

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