Difference Formula
Mathematical models for color tolerance provide a way to align instrumental readings with the way the human eye perceives shade variations. The cmc 2: 1 formula uses an elliptical volume around the standard color to determine if a production sample is an acceptable match. It applies different weights to lightness and chroma to better mimic visual sensitivity.
Ellipsoidal Volume
Human vision is more tolerant of shifts in brightness than shifts in actual hue. The cmc 2: 1 calculation accounts for this by making the acceptance ellipse longer in the lightness direction. This ensures that a sample that looks like a match to a person also passes the instrument test.
Visual Correlation
Industrial applications prefer this specific ratio for most apparel and textile products. Because the cmc 2: 1 model was developed using thousands of visual observations of fabric, it is more reliable than older linear formulas. It reduces the number of samples that are rejected by the computer but accepted by a trained colorist.
The ratio can be adjusted for specific end uses like automotive trim or thread, but the 2 to 1 setting remains the standard for the garment industry.
Pass Fail Logic
Quality control software uses the resulting numerical value to give an instant decision. Any value below 1.0 generally signifies a commercially acceptable match.
