Textile coloration - what is Textile coloration

It helpful to think of Color Space in terms of a color tree.COLOR SPACE The Lightness scale is arrangedfrom top to bottom.. Color SpaceIf we look at a cross section of the color tree, we

TEXTILE COLORATION

CMC (Colour Measurement Combination):

DL(-) = DARKER; DL(+) = LIGHTER; Da(+) = REDDER; Da(-) = GREENISH; Db(-)= BLUEISH.

Color are divided in following class

PANTONE BOOK (TCX, TPX):

This book is used for shade matching Sometime buyer gave the pantone no in their order Pantone no indicates the shade of the garments It’s a universal shade matching book

Full name : Pantone Textile Color Selector

Color numbering system : 6 digit + suffix

First two digits : 11 to 19 (range of lightness)

Middle two digits : 01 to 64 (range of hue)

Last two digits : 01 to 65 (range of chroma)

Color combination Chart on basis On factory

Color

dyes

Black White Blue/green Brawon Avg RSPCL

COLOR SPACE

It helpful to think of Color Space in terms of a color tree.

COLOR SPACE

The Lightness scale is arrangedfrom top to bottom The Light-ness scale forms the first dimen-sion of this color space

The Lightness value of a color isreferred to by the letter L Black will have low L value and white willhave a high L value

Color Space

If we look at a cross section

of the color tree, we can see

Hue (color) is arranged in continuous scale from red to violet This dimension is

referred by the letter H

Chroma, referred to by letter C,

is increasing outwards from the centre point, where neutral

starting with grey, and gradually increasing in saturation to the periphery

If we work with a cross section

of the color tree as CIELab space,this space is divided by two

axes which intersect at a grey neutral area in the centre

“a” is the red-green axis which

is red on the positive side and green on the negative side

“b” is the yellow-blue axis which

is yellow on the positive end andblue on negative end

Today the most widely used of

the opponent-type scales is the

CIELab color scale It was

adopted in 1976 and identifies

object color using three

coordinates (L*a*b*)

The tristimulus XYZ values of a

color, when converted to L*a*b* values, do a better job of

describing the color as seen by

an observer

Color Difference

CIELAB (L*a*b*) values are used to represent product colors.They can be plotted in Color Space and then used to calculate color differences between the established product “standard” and a “batch”

Color Difference

A color difference measurement is calculated by subtracting the L*a*b* of standard from the batch Differences seen in the

previous examples are illustrated below.

Batch Std Diff Visual Terms

L*= 40 50 - 10 Darker a*= 20 30 - 10 Less Red b*= 30 20 10 Yellower

We can now calculate the totall color difference between theStandard and the Batch by calculate the distance between thesamples in all three dimensions.(L,a,b)

Color Difference

The difference between the L value of the Std and Batch is

called delta L* or DL* In this example DL* = -10 The difference between the “a” value is also calculated to determine a redness

-greenness This difference is called delta a* and it represented

by symbol Da* Here Da* = -10 The same calculation is also

performed to determine the yellow-blueness of the Std and

Batch This difference is called delta b* or Db* In this example

Db*=10.

DL*,+ DL = Lighter Da*, + Da* = Redder or Less Green

- DL = Darker - Da* = Greener or Less Red

Db*, + Db*= Yellower or Less Blue

- Db*= Bluer or Less Yellow

In the conclusion, DL*, Da* and Db* can be describe as:

is higher the chroma in color

Chroma difference is referred by

DC*, if DC* is positive a batch has

a higher chroma (stronger); if negative DC* a batch is weaker than Std

As Hue difference is an angular difference, it is not in

CIELAB unit and therefore the preferred component, so

DH* can be calculate by DH*=[(DE)2 -(DL*)2-(DC*)2 ]1/2

Total Color Difference

A color difference equation using DL*, Da* and Db* to calculate the Total Color Difference between Std and the Batch This Total Color Difference is called delta E and itrepresented by symbol DE* DE* can be calculated using

this equation;

DE* = [(DL*)2 + (Da*)2 + (Db*)2 ]1/2

With reservation it can be said that color difference DE* >1

Color Tolerance

Individual delta’s of CIELAB can be use for set up color

tolerance instead of single number DE* The step to settingcolor tolerance will be discuss as follows;

1 Select a large population of sample from actual

production which show all the possible process variations

2 Visually acceptable & unacceptable are separated when

compare to standard

3 Instrumental color difference measurement of these

samples are made and then plotted to define a tolerance area with acceptability limits

4 Data collected is then plotted in CIELAB chroma (a*/b*)

diagram In time it will define a tolerance area

All the trials falling

within the elliptical

area are considered

“visually acceptable”

and those outside are

visually unacceptable

The key to this type of

work is defining the

individual tolerance

area for a given STD

color

Color Tolerance

Color Tolerance

A tolerance area shaped like a box is inadequate in containing only the

visually acceptable samples Experience has show that observer do not accept and reject based on the neat, symmetrical

tolerance boxes

When color differences are plotted they invariably from

something closer to an ellipse in shape, rather than a

rectangle or square