The technical foundation of SMS
For those who need to know exactly how it works.
This page documents the scientific, mathematical, and procedural foundations of the Spot Matching System (SMS). It is intended for technical professionals, print specialists, color scientists, and production environments where measurable accuracy is required.
Spectral data methodology
SMS colors are defined using measured spectral reflectance data rather than visual appearance or ink recipes.
Each color is measured across the visible spectrum using ISO-compliant spectrophotometric instruments. The resulting spectral curve represents how the color interacts with light under defined conditions.
This spectral definition ensures that:
- Colors are material-independent
- Colors are device-independent
- Reproduction does not rely on visual matching
Spectral data acts as the single source of truth from which all other representations (LAB, RGB, CMYK) are derived.
LAB & ICC handling
SMS uses CIE LAB as the core working color space because it is device-independent and closely aligned with human visual perception.
From the spectral definition:
- LAB values are calculated under defined illuminant and observer conditions
- ICC profiles are used to translate LAB values into device-specific color spaces
ICC profiles ensure consistent translation across:
- Displays (sRGB / Rec.709)
- CMYK printing (ISO 12647, G7, Japan Color)
- Digital production workflows
SMS does not embed fixed CMYK values. Instead, CMYK values are derived dynamically based on the target output condition.
Measurement instruments
SMS measurements are performed using ISO-certified spectrophotometers operating under standardized conditions.
Key requirements:
- Measurement condition M1
- Illuminant D50
- Controlled UV content
These conditions account for optical brighteners in modern substrates and ensure reproducibility across locations and time.
Measurement instruments must be:
- Regularly calibrated
- Verified against reference standards
- Operated under controlled environmental conditions
Verification process
Verification is the process of confirming that a produced color matches the SMS definition within defined tolerances.
Verification involves:
- Measuring the produced sample
- Comparing measured values to the SMS reference
- Evaluating ΔE differences
Verification replaces visual approval with measurable confirmation.
If values fall within tolerance, the color is correct — regardless of subjective perception.
ΔE tolerances
SMS uses ΔE (Delta E) as the quantitative measure of color difference.
ΔE defines:
- How far a produced color deviates from the reference
- Whether a deviation is acceptable or not
Accuracy does not mean perfection.
It means remaining within agreed
tolerances.
Defined tolerances allow:
- Objective decision-making
- Clear acceptance criteria
- Elimination of disputes
Standards compliance
SMS aligns its technical framework with international standards to ensure consistency and interoperability.
Key standards include:
- ISO 12647 (print production)
- ISO 3664 (viewing conditions)
- CIE colorimetric standards
- ICC color management framework
Standards provide the shared reference that allows measured color to function globally across suppliers, devices, and regions.
SMS READY certification
SMS READY certification indicates that a device, workflow, or supplier is capable of producing and verifying SMS colors correctly.
SMS READY environments:
- Operate within defined standards
- Use calibrated instruments
- Follow verified workflows
Certification ensures that SMS colors behave predictably throughout the supply chain.