Color Systems

Subtractive Color The removal of light waves to perceive color: –Local or physical attributes of pigments, dyes, or inks reflect certain primary (RGB) wavelengths while absorbing others. –When pigments are all overlapped they absorb all light wavelengths to form black.

Subtractive Primaries The primary colors in the subtractive system are Cyan, Yellow, and Magenta (The same colors used in printing) Notice what colors are prevalent as middles to Red, Green and Blue in the Visual Spectrum.

Additive Color Based on Maxwell’s “Trichromatic theory” Red, Green and Blue become primary wavelength colors when mixed together form white. Applications: TV, Computer Graphics, Web Design, Holography, Stage Lighting, Photography

Color images The goal of the designer is to accurately reproduce colors as they appear in the original subject (whether it be an original work or from nature) or to have full power over how they are changed 1 st generation images typically have better color because they are original (digital cameras) 2 nd generation images are usually dependant on the designer and media to create accurate color

Things that an affect the control of color: Photography: –Grain –Exposure –Density Transparencies Resolution (dpi / ppi) Color / Bit Depth Gamut Shift

More on gamut: Gamut refers to the color range dependent on color model Human perception is roughly 16.7 million colors The challenge to the designer is to increase the range of colors in their media in order to more accurately reproduce their image

Color systems as they relate to computer applications: RGB –Additive Color system and should be used for any media that reproduces color with light. –RGB combined at varying intensities to create any color in the visible spectrum (demonstrate) –Device Dependant – various factors can affect the appearance of the color

Web Safe Dependant on type of monitor, many colors can be perceived differently so “Web Safe” colors are basic colors that are typically perceived the same on all monitors.

CMYK “Process Color” (subtractive color system) Overlapping of layers of inks (Cyan, Magenta, Yellow, and Black) in varying percentages to create color (demonstrate) Full mixture of pigments gives a muddy brown and not black so black ink was added to extend the range of printable colors Device Dependant

Hexachrome “Hifi” color (High-fidelity color) Standard printers have 4 inks (CMYK), hifi adds two more colors to extend the gamut. These colors were historically green and orange, however more recent printers have warmer and cooler versions of the subtractive primaries and options for increasing the gamut in any direction one wishes. Developed by PANTONE

Special Color Libraries Usually used in 2 or 3 color documents to more accurately produce colors. Uses user defined “spot” colors

L*a*b* color space Defined by an international standards making body in 1931 and renamed in 1976 Defines the physical characteristics of color without considering any specific output device L* - Luminance of color expressed by a percentage a* - Defines the color on a red/green axis (-128 to 128) b* - Defines the color on a yellow/blue axis (-128 to 128)