Television 1 Jess Role @ UEAB2006

Principles of Color Television

Television 1 Jess Role @ UEAB2006

Three Basic Colors of Television

• Blue

• Red

• Green

11 %

30%

59 %

Television 1 Jess Role @ UEAB2006

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 -

Television 1 Jess Role @ UEAB2006

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

Television 1 Jess Role @ UEAB2006

Electromagnetic Spectrum

Television 1 Jess Role @ UEAB2006

Color Mixing

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

Television 1 Jess Role @ UEAB2006

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.

Television 1 Jess Role @ UEAB2006

Spectrum of White light

Television 1 Jess Role @ UEAB2006

Additive Mixing

Television 1 Jess Role @ UEAB2006

Result of Additive Mixing

Television 1 Jess Role @ UEAB2006

Result of 3 color additive mixing

WhitePale

yellowGray pink

Pale green

BluishGreen

100%White

50%White

50 %Saturated

red

50%Saturated

Yellow

Television 1 Jess Role @ UEAB2006

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

Television 1 Jess Role @ UEAB2006

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

Television 1 Jess Role @ UEAB2006

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.

Television 1 Jess Role @ UEAB2006

Color Television Transmission

Television 1 Jess Role @ UEAB2006

Matrix Y Color Transmitter

Television 1 Jess Role @ UEAB2006

G-Y Matrix

• (R –Y) + Y = R

• (B – Y) +Y = B

• (G – Y) + Y = G

Television 1 Jess Role @ UEAB2006

Y color Receiver

Television 1 Jess Role @ UEAB2006

Balance Modulator

Television 1 Jess Role @ UEAB2006

Color Burst color synchronizing

Television 1 Jess Role @ UEAB2006

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.

Television 1 Jess Role @ UEAB2006

Three phasors properties

• Length

• Speed of counter clockwise rotation

• Relative angular position

Television 1 Jess Role @ UEAB2006

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

Television 1 Jess Role @ UEAB2006

COLOR PHASE ANGLE

Television 1 Jess Role @ UEAB2006

Television 1 Jess Role @ UEAB2006

Misconvergence

Television 1 Jess Role @ UEAB2006

Television 1 Jess Role @ UEAB2006

Low green adjustment

Television 1 Jess Role @ UEAB2006

High adjustment of blue

Television 1 Jess Role @ UEAB2006

Dominant Red missing green

Television 1 Jess Role @ UEAB2006

Dominant Blue Missing Green

Television 1 Jess Role @ UEAB2006

Missing Red

Television 1 Jess Role @ UEAB2006

Too much Blue adjustment

Television 1 Jess Role @ UEAB2006

Low red adjustment

Television 1 Jess Role @ UEAB2006

Low green and blue adjustment

Television 1 Jess Role @ UEAB2006

Low red and green color adjustment