Color fatness

COLOR FATNESS

Colour

• Colour is a sensory perception. Light falls on an object and,depending on the colour of the object, waves are partially absored. The light that is not absorbed falls on the

colour receptors in the eye. These convert the incident light stimuli,which are then sent via nerves to the brain. Here the stimuli are interprited, and a colour perception is formed.

Colour Communication

• Munsell Color System

• Pantone

• CIE Lab (CIE L*a*b*)

• CIE LCh (CIE L*C*h)

CIE L*a*b* Scale

CIE 1976 L*a*b* is a color scale based on the Opponent Color Theory. This theory assumes that the receptors in the human eye perceive color as the following pairs of opposites.

• L scale: Light vs. dark where a low number (0-50) indicates dark and a high number (51-100) indicates light.

• a scale: Red vs. green where a positive number indicates red and a negative number indicates green.

• b scale: Yellow vs. blue where a positive number indicates yellow and a negative number indicates blue.

Measuring Colour using CIE L*a*b*

The L value for each scale

therefore indicates the level

of light or dark, the a value

redness or greenness, and

the b value yellowness or

blueness.

All three values are

required to completely

describe an object‘s color. A

three-dimensional

representation of L, a, b

color space is shown here.

CIE LAB Color Space Diagram

To assess colour differences between samples, the difference in location of samples in CIE L a b colour space is used widely in textiles. Total colour difference,ΔE,is the actual distance in CIE L a b colour space between samples.

ΔE ﹦ [ (ΔL)² ＋(Δa)² ＋(Δb)²] ^½