Gamut

Incomputer graphicsandphotography,thegamut,orcolor gamut/ˈɡæmət/,is a certainsubsetofcolors.Most often it is a subset of colors, which can beaccuratelyrepresented by someoutput device.

Another sense refers to the completesetof colors found within an image.

Introduction

The termgamutwas adopted from music, where in middle ageLatin"gamut" meant the entire range ofmusical notesof which musicalmelodiesare composed. In the 1850s, the term was used for a range ofcolorsorhue,for example byThomas De Quincey,who wrote "Porphyry,I have heard, runs through as large a gamut of hues asmarble."

Incolor theory,the gamut of a device is the portion of thecolor spacethat it can show.

When certain colors cannot be presented within a particularcolor model,those colors are said to beout of gamut.

While processing adigital image,an image is usually recorded inRGB color model.When printing such image has to be converted from an original RGB color space to the printer'sCMYK color space.During this process, the colors, which are out of printer's gamut areconvertedto the in-gamut colors. So, the final image is anapproximationof the original one.

Representation of gamuts

A comparison of the colors enclosed by some color spaces.

Gamuts are commonly represented as areas in the full visible range of colors. The full range of colors is usually shown asCIE 1931 chromaticity diagramshaped like ahorseshoe.

The gamut depends on thebrightness.So a full gamut is represented in3Dspace.

Comparison of gamut of some devices

The list contains some typical devices, wich show pictures, ranging from large to small color gamut:

• Laser video projectoruses threelasersto produce the broadest gamut available today. Because lasers produce trulymonochromaticprimaries.More than three lasers can be used together to increase the gamut range.
• Photographic filmcan reproduce a larger color gamut than typical television or computer.
• CRTdisplays have a roughly triangular color gamut, which covers a large portion of the visible color space. In CRTs, the limitations are due to thephosphorsin the screen which produce red, green, and blue light.
• Printingtypically uses theCMYKcolor space (cyan,magenta,yellow,andblack). Efforts have been made to expand the gamut of the printing process by addinginksof non-primary colors.
• Amonochromedisplay's color gamut is a one-dimensional curve in color space.

Other websites

• Using the Chromaticity Diagram for Color Gamut Evaluationby Bruce Lindbloom.
• Color Gamut Mappingbook by Jan Morovic.
• Quantifying Color Gamutby William D. Kappele
• Stanford University CS 178interactive Flash demoexplaining color gamut mapping.