NTSC COLOR BARS

TRANSMISSIONENGINEERING

Picture Monitor

White Black

100

90

80

70

60

50

40

30

20

10

0

-10

-20

-30

-40

Waveform Monitor+10

0

+7.5

-40

-20

0

+20

IRE Scale

100

90

80

70

60

50

40

30

20

10

0

-10

-20

-30

-40

+100

+20

-20

+100

+38

+12

+100

+89

+7

+77+72

+46

-5

-16 -16

+7.5

Waveform MonitorPicture Monitor

FULL FIELD COLOR BARS

IRE Scale

100

90

80

70

60

50

40

30

20

10

0

-10

-20

-30

-40

+100

+69

+56

+48

+36

+28

+15+7.5

+31

-31

+20

-20

+44

-44

+41

-41

+41

-41

+44

-44

+31

-31Luminance - only

Chrominance - only

Waveform Monitor Display

IRE Scale

Picture Monitor

Black Video

100

90

80

70

60

50

40

30

20

10

0

-10

-20

-30

-40

Waveform Monitor+100

+7.5

-40

-20

0

+20

BLACK BURST SIGNAL

IRE Scale

NTSCCOMPOSITE VIDEO

• For color television, the composite video signal includes the 3.58 MHz chrominance signal

• The color signal has a color sync burst on the back porch of horizontal sync

• This burst consist of 8 to 11 cycles of the 3.58 MHz color subcarrier signal

• Its purpose is to synchronize the 3.58 MHz color oscillator in the receiver

• The burst and the C signal are both 3.58 MHz, but the burst has no information

Introduction

100%100%

75%75%

67.5%67.5%

12.5%12.5%

Carrier AmplitudeCarrier Amplitude SyncSync

Front PorchFront Porch

Back PorchBack Porchwith color burst with color burst

Horizontal RetraceHorizontal Retraceor blankingor blanking

Introduction

Back PorchBack Porchwith color burst with color burst

Horizontal Blanking Horizontal Blanking IntervalInterval

Color Color BurstBurst

BreezewaBreezewayy

Horizontal Horizontal Sync PulseSync Pulse Back Back

PorchPorch

End of End of Active VideoActive Video

Start of Start of Active Active VideoVideo

Front Porch

Leading EdgeLeading Edge

Trailing Trailing EdgeEdge

Introduction

• The color television system begins and ends with red, green and blue for color information in the scene

• RGB are primary colors that combined to form different mixtures

• Primary colors produce a wide range of color mixtures when they are added together

Basic Video Color

RED

BLUEGREEN

Basic Video Color

MAGENTAYELLOW

(R+G)

CYAN(G+B)

Basic Video Color

(R+B)

59% GREEN

30% RED

100% WHITE

11% BLUE

41%

70%

89%

R

G

B

Basic Video Color

Red + CyanGreen + Magenta

Blue + Yellow

WHITE = R+G+B

100%white

Basic Video Color

30% RED

59% GREEN

11% BLUE

89%

70%

41%

• Any color has three characteristics to specify the visual information– hue or tint, which is what we generally call

the color– saturation, indicates how concentrated,

vivid, or intense the color is– Luminance, indicates the brightness, or

what shade of gray the color would be in a black-and-white picture

Basic Video Color

White

• White light can be considered as a mixture of the red, green and blue in the proper proportion

Basic Video Color

Hue

• The color itself is its hue, or tint– Green leaves have a green hue

– Red apple has a red hue

• The color of any object is distinguished primarily by its hue

Basic Video Color

Saturation• Saturated color are vivid, intense, deep or

strong• Indicates how little the color is diluted by

white– vivid red is fully saturated– when the red is diluted by white, the result is pink,

which is really a desaturated red

• Note: a fully saturated color has no white

Basic Video Color

Chrominance - Chroma• The term is used to combine both “hue “and

“saturation”• In color television, the 3.58 MHz color signal,

specifically, is the chrominance signal• In short, the chrominance includes all the color

information, without the brightness• The chrominance and brightness together

specify the picture information completely

Basic Video Color

NORMAL

Basic Video Color

Chrominance - Chroma

DESATURATED

Chrominance - Chroma

Basic Video Color

SATURATED

Chrominance - Chroma

Basic Video Color

Luminance• Refers to the “brightness” or amount of

light in the picture• The dark portion of an image has a low

luminance, while the light portion has a high luminance– different color also have different luminance

levels or “shades of gray” as viewed on a monochrome picture monitor

Basic Video Color

Basic Video Color

Chrominance - Chroma

Basic Video Color

Luminance

Colorplexed Composite Video

R

G

B

1.0

0

0

1.0

1.0

0

1.00.89

0.700.59

0.410.30

0.110

Y voltage Relative luminance

of each color

59% GREEN

30% RED

100% WHITE

11% BLUE

41%

70%

89%

Colorplexed Composite Video

0.450.59

0.63

0

C signal

0.590.45

0.63

0.59

0.59

0.63

0.63

0.45

0.45

1.00.89

0.700.59

0.410.30

0.110

Y voltage

1.0

0.44

1.34 1.331.18

1.000.93

0.56

0.34- 0.18

00.07

T = Y +/- C

• The early generator produced color bars that were fully saturated at 100%.

• This value means that R,G and B signals into the encoder are at 100% level for peak white, or 100 IRE units.– This method places an unnecessary burden on the transmission

equipment because of the peak excursion on the modulated 3.58 MHz chroma signal

– Ex. Yellow, the maximum level is 33% above peak white,owing to high luminance

– Also, low luminance of the blue bar result in signal amplitudes 33% below black setup

EIA Standard Color Bar

EIA Standard Color Bar

• The standard color-bar signal has been reduced to what is now called 75% color bar

• It simply means that the amplitudes of the R, G, and signals into the encoder are at 75 IRE units

EIA Standard Color Bar

EIA Standard Color Bar

EIA Standard Color Bar

• The values marked on the step, such as +77 for white and +28 for red, are the Y luminance levels for each of the bar– For white bar, subtract 100 IRE to from 7.5 IRE setup yields

92.5 units of signal variation– then taking the 75% of 92.5 units gives 69.375 units– finally, putting back the 7.5 units of setup yields 76.875– approximately/rounded off to 77 IRE units– For red bar, take 30% of 69.375 units for the white bar, which

equals 20.813 units.– then we put back the 7.5 units setup, yields 28.313 units– his value is rounded off to 28 IRE unit

EIA Standard Color Bar

EIA Standard Color Bar

+15

+28+36

+48+56

+6977

Y CYG

MG R

B

EIA Standard Color Bar

100 10089

7772

46

-16-16-5

+7+12

+38

+15

+28+36

+48+56

+6977

Y CYG

MG R

B

3 H 3 H 3 H

Vertical Blanking Interval(vertical retrace/blanking)

Vertical traceVertical trace

VITS

• Vertical Synchronization - 9 lines– Lines 1-3 (3H) - leading equalizing pulse– Lines 4-6 (3H) - vertical sync pulse– Lines 7-9 (3H) - trailing equalizing pulse

• Lines 17,18 & 19 used for test signals– Vertical Interval Test Signal (VITS)

• odd fields– Line 17 - multiburst signal– Line 18 - sine-squared pulse

• even field– Line 17 - multiburst signal– Line 18 - modulated stair- steps signal

VITSLine Assignment

– Vertical Interval Reference Signal (VIRS)• odd fields

– Line 19 - chroma and luminance reference

• even fields– Line 19 -chroma and luminance reference

• Therefore lines 10,11,12,13,14,15 & 16 are free for other uses.

Line Assignment

VIRS