Delta-E (ΔE) measures the perceptual difference between two colours as the human eye sees them. A score of 0 is a perfect match; higher values indicate greater visible difference. AMC uses two independent checks — ΔE and max channel deviation — both of which must pass.
CMC 2:1 thresholds (textile/screen printing)
Imperceptible ΔE < 1
No visible difference. Passes all colour-critical applications.
Barely perceptible ΔE 1–2
Only visible to trained eye under controlled conditions. Acceptable for print.
Noticeable ΔE 2–5
Visible on close inspection. Flag for client approval before running.
Clearly different ΔE 5–10
Noticeable to most people side-by-side. Not suitable without sign-off.
Significant mismatch ΔE > 10
Clearly different colour family or tone. Not suitable as a substitute.
Why two checks?
ΔE alone can mask single-channel drift. A colour can have a low ΔE perceptual score while one channel (typically Red or Blue) has shifted enough to read as a different colour family on a specific substrate or under fluorescent warehouse lighting. The max channel cap (15% standard / 10% critical) catches this independently.
Why CMC 2:1? The 2:1 ratio weights lightness (L) at half the sensitivity of chroma (C) and hue (H). This reflects how the human eye is less sensitive to lightness variation on a matt fabric surface than to hue shift — which is exactly the failure mode that matters in screen printing. CIE76 weights all three dimensions equally, which overpenalises slight lightness variance and under-penalises hue shift.
Pantone data note:
Hex values for Pantone Solid Coated codes are sRGB approximations. Always cross-check against a printed Pantone fan deck under D50 lighting for press-critical work. Document the formula and viewing condition in client colour approval forms.