Modeling spectral filtering effects on color-matching functions: Implications for observer variability

TL;DR

This paper presents a novel computational method to model spectral filtering effects on color-matching functions, revealing how observer variability, such as lens yellowing, can be efficiently represented by a single filter, reducing experimental complexity.

Contribution

The study introduces a new approach to estimate spectral filters transforming unfiltered to filtered CMFs, linking observer differences to age-related lens yellowing with improved efficiency.

Findings

Good agreement between estimated and measured filter characteristics.

Identified a 'yellow' filter that explains differences between CMF datasets.

Observer variability can be modeled with a single spectral filter.

Abstract

This study investigates the impact of spectral filtering on color-matching functions (CMFs) and its implications for observer variability modeling. We conducted color matching experiments with two observers, both with and without a spectral filter in front of a bipartite field. Using a novel computational approach, we estimated the filter transmittance and transformation matrix necessary to convert unfiltered CMFs to filtered CMFs. Statistical analysis revealed good agreement between estimated and measured filter characteristics, particularly in central wavelength regions. Applying this methodology to compare between Stiles and Burch 1955 (SB1955) mean observer CMFs and our previously published "ICVIO" mean observer CMFs, we identified a "yellow" (short-wavelength suppressing) filter that effectively transforms between these datasets. This finding aligns with our hypothesis that observed differences between the CMF sets are attributable to age-related lens yellowing (average observer age: 49 years in ICVIO versus 30 years in SB1955). Our approach enables efficient representation of observer variability through a single filter rather than three separate functions, offering potentially reduced experimental overhead while maintaining accuracy in characterizing individual color vision differences.