Our brain perceives purple when it receives an equal mix of blue and red light. This phenomenon occurs because purple isn't a spectral color found in the rainbow; rather, it's a color our brains create.
Understanding Color Perception
The Role of Light
- Visible Spectrum: Our eyes can only detect a specific range of electromagnetic radiation, known as the visible spectrum. This spectrum contains colors like red, orange, yellow, green, blue, and violet.
- Spectral Colors: These are pure colors present in the visible spectrum, such as red, blue, and green, each corresponding to a specific wavelength of light.
- Non-Spectral Colors: Colors like purple and magenta are not part of the visible spectrum. They are created by the brain when it processes a combination of different wavelengths of light.
How We See Purple
| Wavelength | Color |
|---|---|
| Red | Red |
| Blue | Blue |
| Red + Blue | Purple |
- Equal Mix: The sensation of purple arises when our eyes receive a mixture of red and blue light simultaneously.
- Brain Interpretation: The brain takes these two signals, neither of which by themselves create the sensation of purple and combines them into what we understand as the color purple.
- Magenta: Similar to purple, magenta is also a non-spectral color. It's our brain's way of perceiving a mix of light from the two ends of the visible spectrum (red and violet/blue).
Examples
- Paint Mix: If you mix red and blue paint, you will perceive purple, this is because the pigments in the paint will absorb all the other colours, and reflect the red and blue light, which then goes into our eyes,
- Stage Lighting: In theatre or concerts, purple lighting effects are achieved by blending blue and red light sources.
Summary
The perception of purple is a fascinating example of how our brains actively create the colors we see. It's not a wavelength that exists by itself in the visual spectrum. Instead, it is an interpretation of a specific combination of light.
