What are metamers in color science?

• A. A type of material used to filter colors.
• B. Different spectral distributions of light that produce the same cone responses, making colors visually identical.
• C. The same spectral distribution under different lighting conditions.
• D. Colors that cannot be distinguished by the human eye.

Answer: (B)

Metamers arise because color perception compresses the spectrum into signals from three kinds of cones in the eye. A metamer is a pair (or set) of different spectral power distributions that, when viewed under the same lighting, trigger the same responses from all three cone types. Because the brain interprets color from these three signals, the two spectra look the same even though their wavelengths differ. This explains why two paints or lights can appear identical under one lighting condition but may diverge under another, and it underpins why color matching is possible with different spectral compositions. The other options describe ideas that aren’t about how color perception reduces spectral content to cone responses, such as filtering materials, identical spectra under different illumination, or colors that can’t be distinguished due to vision deficiencies.