Principles of Color Television

Three Basic Colors of TelevisionBlueRed Green11 %30%59 %

Three Color CharacteristicsHue adjusted color sometime called tint control (from green to red) Brightness illumination of the picture that includes sharpness of edges including the contrast controlSaturation -

Lights430 Terahertz (430 X 10 Hz) to 750 Terahertz (750 X 10 Hz)430 Terahertz is considered as a wavelength750 Terahertz correspond to the color red and the higher frequency400 nm seen deep blueSome colors do not correspond to any one given wavelength of light (example brown and purple)

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Electromagnetic Spectrum

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

Subtractive color mixingSubtractive 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.

Spectrum of White light

Additive Mixing

Result of Additive Mixing

Result of 3 color additive mixingWhitePale yellowGraypinkPale greenBluishGreen100%White50%White50 %Saturatedred50%Saturated Yellow

Luminance LevelDark yellow producing a shade of gray approaching black Y= 0.59G + 0.39R + 0.11BFor equal EnergyY = 0.59(1) + 0.30(1) + 0.11(1)=1.00For 50 % red 100% blue 100% greenY = 0.59G + 0.30R + 0.11B= 0.59(1) + 0.30(1) + 0.11(1)= 0.59 + 0.15 + 0.11=0.85

Object size and colorA 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

continuationLuminance signal information has required bandpass from 0 to 4.2 MHZThe narrower the bandwidth of the color information the less complex the color tv system need be.

Color Television Transmission

Matrix Y Color Transmitter

G-Y Matrix(R Y) + Y = R(B Y) +Y = B(G Y) + Y = G

Y color Receiver

Balance Modulator

Color Burst color synchronizing

Phase relationshipThe 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 transmittedPhasor a sine and cosine waves can be represented by a straight line.

Three phasors propertiesLengthSpeed of counter clockwise rotationRelative angular position

Performance of the chrominance signalY =0.59G + 0.30R + 0.11B=0.599(0) +0.30(0) + 0.11(0) = 0.41R Y = 0.70R 0.11B 0.59G=0.70(1) 0.11(1) 0.59(1) = 0.59B Y 0.89B 0.30R 0.59G=0.89(1) 0.30(1) 0.59(0) = 0.59

COLOR PHASE ANGLE

Misconvergence

Low green adjustment

High adjustment of blue

Dominant Red missing green

Dominant Blue Missing Green

Missing Red

Too much Blue adjustment

Low red adjustment

Low green and blue adjustment

Low red and green color adjustment