The roses lose their redness. Beside a wall of red blooms, a white cat encounters a visual display whose color carries less force than it does for human observers, because feline eyes distinguish reds poorly. Beauty has different audiences. What appears richly red to people need not produce an equally distinct color sensation in the animal sitting beside it.
Color is not everything. Cats have cone photoreceptors supporting broadly dichromatic vision, with greater sensitivity to short and medium wavelengths than the capacity humans possess to separate reds from greens. The difference matters here. A rose remains visible through its outline, brightness and contrast against surrounding leaves, even when its redness supplies little useful information to feline eyes. Exact shades resist translation. Describing every red flower as gray oversimplifies a perceptual experience that depends on illumination, the reflecting surface and visual processing, rather than a simple substitution of one human color name for another.
Dimness changes the advantage. A feline retina contains abundant rod photoreceptors, which respond sensitively to light but do not provide the color discrimination associated with cones under brighter conditions. Reflections help as well. Behind the retina, the tapetum lucidum returns some incoming light through the photoreceptors, increasing the opportunity for detection when illumination is scarce, though cats cannot see in complete darkness. White fur changes nothing. As the light fades across the rose wall, its celebrated redness matters less than the edges and faint contrasts that remain available to the waiting cat.
