CIELAB

Coordinate System

The vertical L axis spans from zero for absolute black to one hundred for perfect diffuse white. Along the horizontal axes, positive a indicates red while negative a indicates green, and positive b represents yellow while negative b shows blue. Textile colorists use these values to establish the position of a production batch against a master standard.

When the measured values deviate from the target, the direction and magnitude of the difference guide the dyer in adjusting the dye bath concentration. For example, if the L value is too high, the fabric is too light and requires additional dye cycle time.

Factory Standard

Digital dye recipe systems rely on these coordinates to calculate the adjustments needed during the finishing process. Mill operators compare the values of the dyed yarn to the target coordinates to decide if a load needs more dyestuff. The system works well for solid shades but becomes less reliable for textured yarn or heather blends where light scatters unevenly.

Measurement Limit

Spectrophotometers measure the raw reflectance data before converting them into these coordinates under specific light sources. Because of this dependency, the coordinates change if the light source changes. The system does not account for texture or gloss variations which can cause a visual mismatch even when the numbers match.