Color Models: RGB and CMYK

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Questions and Answers

What is the outcome when you add portions of red, green, and blue in the RGB color model?

Cyan

White (correct)

Magenta

Black

What is the principle of the CMYK color model?

Reflective color

Subtractive color (correct)

Additive color

Absorptive color

When is it best to use the RGB color model?

When designing a website

When displaying on a computer monitor (correct)

When printing a document

When creating a logo

What does HSL stand for in the HSL color model?

Hue, Saturation, Lightness Signup and view all the answers

What does a saturation value of 0 indicate?

A color with mostly grey Signup and view all the answers

What is the range of the hue value in the HSL color model?

0 to 360 Signup and view all the answers

What is the effect of increasing the saturation value in the HSL color model?

The color becomes more intense Signup and view all the answers

What is the difference between HSL and HSV color models?

A color with maximum lightness in HSL is pure white, but a color with maximum value/brightness in HSV is analogous to shining a white light on a colored object Signup and view all the answers

What does the 'L' component in the LAB color model represent?

Luminosity from black to white Signup and view all the answers

What is the purpose of the lightness value in the HSL color model?

To adjust the brightness of the color Signup and view all the answers

What is the purpose of the YUV color model?

To separate brightness and color information, especially for video Signup and view all the answers

What is the alternative color model to HSL?

HSV Signup and view all the answers

What is the formula for deriving Luma (Y) in the YUV color model?

Y = 0.2125R + 0.7145G + 0.0721B Signup and view all the answers

What are the three values that represent any color in the YUV color model?

Y, U, and V Signup and view all the answers

What does the 'B' component in the LAB color model represent?

Blue from -128 to +127 Signup and view all the answers

What is the advantage of the HSL and HSV color models?

They are more closely aligned with the way human vision perceives color-making attributes Signup and view all the answers

What is the basis of color reproduction in monitors?

Standard red, green and blue as primaries Signup and view all the answers

What is the purpose of using indexed color?

To reduce the size of image without using lossy compression Signup and view all the answers

How many colors can be represented by an 8-bit color component?

256 colors Signup and view all the answers

What is the term used to describe 216 colors that are guaranteed to reproduce accurately on all platforms and browsers?

Web-safe palette Signup and view all the answers

How do TVs and computer monitors produce colors?

By using optical mixing of red, green, and blue light Signup and view all the answers

What is the minimum number of bits required to represent 256 grays in an image?

8 bits Signup and view all the answers

What is the term used to describe the number of bits used to represent each color component?

Color depth Signup and view all the answers

What is the advantage of using a 24-bit color representation?

It can represent millions of colors Signup and view all the answers

Study Notes

RGB Color Model

Also known as "additive color"
Colors are added together to achieve further colors, with the outcome being white
Our eyes receive no reflected light, perceiving black when no colors are added

CMYK Color Model

Subtractive color model
Starts with all colors and subtracts to achieve white
Colors absorb light

When to Use RGB vs CMYK

Use RGB for computer monitor output
Use CMYK for printed materials

HSL Color Model

Supported in modern browsers
Stands for Hue, Saturation, and Lightness
Hue is a degree on the color wheel (0-360)
Saturation is the intensity of a color (0-100%)
Lightness is how much light is given to the color (0-100%)

HSV Color Model

Alternative way of specifying color
Hue is the actual color (0-360)
Saturation indicates the amount of grey in a color (0-100%)
Value (brightness) refers to how much white or black is mixed in the color

HSL vs HSV

HSL: maximum lightness is pure white
HSV: maximum value/brightness is shining a white light on a colored object

LAB or CIE Color Model

L: lightness from black (0) to white (100)
A: from green (-128) to red (+127)
B: from blue (-128) to yellow (+127)

YUV Color Model

Defines a color space in terms of one Luma (Y) and two chrominance (UV) components
Can separate brightness and color information
Luma is derived from an RGB color by taking a weighted average of the red, green, and blue components

Color

A particular color is defined by the proportions of red, green, and blue light it contains
TVs and computer monitors use pixels made up of three dots of different types of phosphor, emitting red, green, and blue light

RGB Color Storage

Represent any color with three numbers (r, g, b)
Use as pixel's stored value in bitmapped image
Can choose number of bits for each of r, g, and b
More bits per component means more colors can be distinguished, but image files will be larger

Color Depth

8 bits (1 byte) per component -> 256 colors
24-bit -> millions of colors
If r = g = b, color is a shade of grey

Indexed Color

8-bit color only permits 256 colors
Instead of storing (r, g, b) for each pixel, store an index into a palette or Color Lookup Table (CLUT)
Index can be small, usually a single byte

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Description

Understand the difference between RGB and CMYK color models, also known as additive and subtractive color models, and how they work.