Figure 2

Spectral power distributions of visual stimuli that are metamers of each other. Each stimulus intensity for L-, M-, and S-cones is identical, and each stimulus intensity for rods of (A,B) is also identical. Numerical values in the figure indicate melanopic/photopic ratio (M/P ratio) defined by \(4557\int i(\lambda )P(\lambda )d\lambda /683\int V(\lambda )P(\lambda )d\lambda \). These values represent the stimulus intensity on melanopsin per 1 cd/m².