Tone Value Increase Target Derivation for Uncoated Papers
Deriving uncoated paper TVI targets demands separating optical light scattering from capillary ink absorption using M1 spectral data to set inverse RIP curves.
Spectral Reflectance
Optical Measurement
Wavelength-dependent light reflection measurement quantifies the percentage of incident light reflected from a paper surface or printed ink film across visible light spectrum wavelengths. Color scientists evaluate spectral reflectance to characterize paperboard brightness, shade, optical brightener response, and metamerism characteristics independent of specific lighting environments. Precise spectral curves provide complete optical fingerprints that inform precise ink formulation and substrate grading.
Wavelength Analysis
Spectrophotometers shine controlled light onto paperboard samples and measure reflected light intensity at narrow wavelength intervals across the visible spectrum. Optical analysis software plots percentage reflection values against wavelength curves to identify subtle color variations undetectable by standard trichromatic filter densitometers. Paper mills monitor spectral curves during pulping and coating operations to maintain consistent substrate whiteness and compensate for raw fiber tint shifts.
Formulators analyze spectral data from printed ink films to calculate exact pigment combinations needed to match target brand colors on specific paper substrates. Measuring spectral data under multiple illuminant conditions reveals metameric color shifts where sample matches under daylight but diverges under store lighting. Quality control automated scanning systems scan high-speed paper webs continuously to flag spectral variance before rolls are cut into sheets.
Substrate Boundary
Optical measurement protocols apply to physical light reflection analysis of paper substrates and printed ink surfaces. Analysis of spectral reflectance provides the fundamental optical data required for accurate color management across paperboard converting operations.