Measurement of the Imperceptible Threshold for Color Vibration Pairs Selected by using MacAdam Ellipse

TL;DR

This work addresses generating color-vibration pairs that appear imperceptible to humans by incorporating perceptual nonuniformities captured by the MacAdam ellipse. The authors define color-vibration pairs along the ellipse’s long axis using $\mathbf{p}^{\pm}_n(r)$, with luminance fixed at $Y=0.4$ and colors mapped through $xyY$ to $XYZ$ then to sRGB under a $2^\circ$ CIE observer with D65. An experiment with $n=10$ observers and 46 test pairs finds a 50% flicker percept threshold at $r=24.4$, suggesting a roughly $24\times$ tolerance relative to spatial discrimination. The results provide a scalable, perceptually informed guideline for selecting imperceptible color-vibration pairs and can be extended by interpolating across MacAdam ellipses for broader color coverage.

Abstract

We propose an efficient method for searching for color vibration pairs that are imperceptible to the human eye based on the MacAdam ellipse, an experimentally determined color-difference range that is indistinguishable to the human eye. We created color pairs by selecting eight colors within the sRGB color space specified by the ellipse, and conducted experiments to confirm the threshold of the amplitude of color vibration amplitude at which flicker becomes imperceptible to the human eye. The experimental results indicate a general guideline for acceptable amplitudes for pair selection.

Figures (2)

• Figure 1: Images of 8 colors defined by the MacAdam ellipses used to generate color vibrations in the experiment.
• Figure 2: Percentage of responses perceived flicker relative to $r$. The blue dots indicate the mean, and the blue line shows the perceptual curve fitted by the sigmoid function.