Colour model

IIITM GWALIOR POWERPOINT PRESENTATION

ON COLOR MODELS

Monika lagwal

CSE

POWERPOINT

PRESENTATION

on

Color model

COLOR MODEL IN

COMPUTER GRAPHICS

Any system for representingcolors as ordered sets ofnumbers.

A color model is an orderly system for creating a whole range of colors from a small set of primary colors.

There are two types of color

models, those that are subtractive

and those that are additive.

Additive color models use light to display color while subtractive

models use printing inks. Colors perceived in additive models are

the result of transmitted light. Colors perceived in subtractive

models are the result of reflectedlight.

COLOR MODELS

THE MOST COMMON COLOUR

MODELS ARE

1.RGB,

2.CMYK,

3. HSB.

THERE ARE SEVERAL OTHERS, E.G.

CMY,HSV,HLS ETC

RGB MODEL

In the RGB model notice that the

overlapping of additive colors (red,

green and blue) results in subtractive

colors (cyan, magenta and yellow.

THE INTENSITY OF EACH OF THE RED,

GREEN AND BLUE COMPONENTS ARE

REPRESENTED ON A SCALE FROM 0 TO

255 WITH 0 BEING THE LEAST INTENSITY

(NO LIGHT EMITTED) TO 255 (MAXIMUM

INTENSITY). FOR EXAMPLE IN THE ABOVE

RGB CHART THE MAGENTA COLOR

WOULD BE R=255 G=0 B=255. BLACK

WOULD BE R=0 G=0 B=0 (A TOTAL

ABSENCE OF LIGHT).

THE MAIN PURPOSE OF THE RGB COLOR MODEL

1.FOR THE SENSING,

2.REPRESENTATION,

3.DISPLAY OF IMAGES IN ELECTRONIC

SYSTEMS, SUCH AS TELEVISIONS AND

Computers.

4. photography.

Use RGB For Screen Displays

CMYK COLOR MODELThe CMYK printing method is also known as "four-color process" or simply "process" color.

For printed material

Uses ink to display color

Colors result from reflected lightCyan + Magenta + Yellow=Black

In the CMYK model notice that the overlapping of

subtractive colors (cyan, magenta and yellow) results in

additive colors (red, green and blue).

THE CMY(K) COLOR MODEL

Used in electrostatic and in ink-jet plotters that deposit pigment on paper

Cyan, magenta, and yellow are complements of red, green , and blue

Subtractive primaries: colors are specified by what is removed or subtracted from white light, rather than by what is added to blackness

Cartesian coordinate system Subset is unit

cube

white is at origin, black at (1, 1, 1):

K = black, which is used instead

of equal amounts of CMY

Magenta

Red

YellowGreen

Cyan

Blue

Black

(minus green)

(minus blue)

(minus red)

B

G

R

Y

M

C

1

1

1

Some examples of 4 Color Process printing in

various stages is below:

COLOR PROCESS PRINTING.

ADVANTAGE:

1. REQUIRES ONLY 4 FILM POSITIVES AND SCREENS

AND, THUS, MAY BE MORE ECONOMICAL.

DISADVANTAGES:

A) CAN ONLY PRINT EFFECTIVELY ON WHITE SHIRTS (UNLESS

USE EXPERTISE DISCHARGE METHOD OF PRINTING).

B) CANNOT GUARANTEE PMS COLOR MATCHES.

C) THE PRINTED IMAGE IS NOT AS VIBRANT AS THAT USING

SPOT COLOR PRINTING SINCE THE INKS USED ARE

TRANSPARENT, NOT OPAQUE.

D) CANNOT CREATE THE COLOR WHITE USING CMYK.

THEREFORE, A SPOT COLOR WHITE WOULD HAVE TO BE

PRINTED IF WHITE IS NEEDED.

E) GENERALLY DOESN'T PRINT AS WELL ON 5.6 OZ FABRIC AND

LIGHTER

SINCE FABRIC WEAVE IS NOT TIGHT ENOUGH

A comparison of RGB and CMYK color

models.

The HSB Color Model

The HSB color model defines three

fundamental properties of color: Hue,

Saturation, and Brightness.

It is predicated on the principle that every

real color originates from a single pure

color (Hue), which is then mixed with

various amount of white or/and black

color to give various shades of that pure

color.

HUE IS THE NAME OR PURE VALUE OF THE COLOR SUCH AS RED,

GREEN, YELLOW, ETC. IT IS MEASURED IN DEGREES FROM 0 TO

360. (0 IS RED, 60 IS YELLOW, 120 IS GREEN, 180 IS CYAN, 240 IS

BLUE AND 300 IS MAGENTA.)

SATURATION IS THE PURITY OF THE COLOR AND IS THE AMOUNT

OF PURE COLOR MIXED WITH WHITE COLOR. IT VARIES FROM

WHITE TO PURE COLOR. IT IS MEASURED IN PERCENT FROM 0 TO

100. THE HIGHER THE PERCENTAGE, THE MORE PURE WILL BE THE COLOR.

BRIGHTNESS DETERMINES THE INTENSITY OF THE COLOR AND

IS THE AMOUNT OF PURE COLOR MIXED WITH BLACK COLOR. IT

VARIES FROM BLACK TO PURE COLOR. IT IS MEASURED IN

PERCENT FROM 0 TO 100. THE HIGHER THE PERCENTAGE, BRIGHTER THE COLOR.

THE HSV COLOR MODEL

Hue, saturation, value

(brightness)

HSB-space invented by Alvy

Ray Smith—described in his

1978 SIGGRAPH paper, Color Gamut Transformation Pairs.

Hex cone subset of cylindrical

(polar) coordinate system

THE HLS COLOR MODEL

Hue, lightness,

saturation

Maximally saturated hues are

at S = 1, L = 0.5

Less attractive for sliders or

dials

Conceptually easier for some

people to view white as a

point

THANK YOU