Lab Dip Approval against Bulk Shade under Three Illuminants
Tri-illuminant shade approval aligns lab dips with bulk by enforcing primary D65 visual matching alongside secondary TL84 and Illuminant A metameric tolerances.
Metameric Index
Numerical Calculation
Quantification of the visual shift between two color samples when viewed under different light sources reveals the stability of a match. The metameric index provides a single value to describe how much a pair of fabrics that look identical under daylight will differ under store lighting.
Illuminant Change
Spectral data from a spectrophotometer allows for the comparison of a production batch against a master standard under D65 and TL84 light. A high metameric index warns the manufacturer that the garment will change hue when a customer moves from the street into a building. This problem occurs because different dye combinations can produce the same visual result under one specific light while having different light reflection properties.
Spectral Data
Reducing this value requires the lab to use the same dye types for the bulk production that were used for the original sample. Calculating the metameric index involves weighing the differences in the reflectance curves across the entire visible spectrum.
Batch Verification
Quality controllers use this data to reject batches that would cause color mismatching in multi component garments. A low metameric index ensures that the sleeves and the body of a jacket match regardless of the environment.