Spectral Standard
Graphic arts standards established by international organizations define a specific power distribution of light to ensure consistent color viewing and measurement. This spectral definition, known as illuminant m1, matches the ultraviolet and visible regions of natural daylight as defined by the D50 standard. It provides a consistent reference point for measuring printed materials on substrates containing optical brightening agents.
By standardizing the amount of ultraviolet energy, it ensures that the fluorescence generated during measurement corresponds to the visual appearance under daylight.
Brightener Activation
Fluorescent molecules in modern printing papers absorb invisible ultraviolet energy and re-emit it as visible blue light to increase perceived brightness. Because older measurement standards did not control the ultraviolet content of the light source, spectrophotometers often yielded inconsistent color data on these brightened sheets. Using illuminant m1 solves this issue by requiring the light source to have a tightly controlled ultraviolet component that closely replicates the D50 spectrum.
This precise activation of optical brighteners allows print houses to predict how the colors will look when displayed in a retail environment. The resulting measurements reduce the need for manual press adjustments and color corrections during production. This alignment between measurement and visual inspection is essential for brand owners who demand uniform color across various packaging materials.
Color Consistency
Digital workflows that manage color across proofing and production devices depend on standard daylight simulation to maintain match accuracy. When substrates with high concentrations of fluorescent whitening agents are measured under illuminant m1, the resulting profiles prevent color shifts that would otherwise occur when the proof is compared to the printed sheet. This standardization minimizes the discrepancies that historically plagued color matching between digital proofs and press sheets.
