Design Concepts: Module A: The Science of Color

Goals Understand the origin of natural color Understand the Additive Color Model Understand the Subtractive Color Model Understand how to represent colors using hexadecimal values

The Electromagnetic Spectrum Measure of photons, traveling at the speed of light, carrying some type of energy Measured in terms of wavelength and frequency

The Electromagnetic Spectrum Image source: http://imagers.gsfc.nasa.gov/ems/waves3.html

Image is from http://imagers.gsfc.nasa.gov/ems/visible.html Visible Light Occurs in a small part of the EM spectrum, near the middle Wavelengths are 400nm to 700nm long Image is from http://imagers.gsfc.nasa.gov/ems/visible.html

Image Source: http://imagers.gsfc.nasa.gov/ems/visible.html Visible Light Image Source: http://imagers.gsfc.nasa.gov/ems/visible.html

Image courtesy of Pat Ellison Additive Color Model Used by computers When light energy is added, a color appears brighter Different visible light wavelengths can be combined to create new colors Image courtesy of Pat Ellison

Image courtesy of Pat Ellison Additive Color Model Image courtesy of Pat Ellison

Subtractive Color Model Used in the print media When more color is added, a color appears darker Ink or paint can be thought of a filter that filters out all colors except the color being perceived, which is reflected Image courtesy of Pat Ellison

Subtractive Color Model Image courtesy of Pat Ellison

Primary Colors Technically, pure primary colors are spectral colors which cannot be mixed from other colors A small number of colors can be mixed to create new colors

Primary Colors The Additive Color Model uses Red, Green and Blue (RGB) as Additive Primaries The Subtractive Color Model uses Cyan, Magenta, Yellow and Black (CYMK) as Subtractive Primaries

Some Color Terms Hue – A specific location on the visible spectrum Saturation – Specifies the amount (intensity) of a color

Some Color Terms Value (Brightness) – Specifies the darkness/lightness of a color. Adding WHITE to a color produces a TINT. Adding BLACK to a color produces a SHADE.

The Color Wheel A common way to map color is to use the Color Wheel All hues are depicted as an angle on the wheel (0° represents RED and 360° represents VIOLET)

The Color Wheel Saturation is represented as a percentage Value is represented as a percentage RED, YELLOW and BLUE are the color wheels primary colors

Image courtesy of Pat Ellison Representing a Color Image courtesy of Pat Ellison

Color as a Numeric Constant Digital Color is normally represented as a numeric constant in triplet format, representing RGB values In many graphic programs RGB values are represented as a percentage (0%-100%) or as an integer (0-255) On the web, color triplets are often represented using hexadecimal numbers

Common Hex Values 51 102 153 204 255 0% 20% 40% 60% 80% 100% 00 33 66 RGB 51 102 153 204 255 PERC 0% 20% 40% 60% 80% 100% HEX 00 33 66 99 CC FF

Common Hex Colors RED (Hex: #ff0000) GREEN (Hex: #00ff00) BLUE (Hex: #0000ff) WHITE (Hex: #ffffff) BLACK (Hex: #000000)

Common Hex Colors MAGENTA (Hex: #ff00ff) CYAN (Hex: #00ff00) YELLOW (Hex: #ff0000) GRAY (Hex: #808080)