All of us rely on tone (brightness, lightness) to interpret what we see. Visual artists have gone to great lengths in tonal modelling, but macOS Tahoe offers only bleached-out white or blacked-out black.
tone
Lightness is key to the depiction of materials, textures, edges, and form. Illusions can confound the viewer, and it is vital to map the lightness of your motif to that of your painting.
The Eclectic Light Company 