Turning the color red into the color green can seem like an impossible task. At first glance, these colors appear completely different and unrelated. However, with some clever mixing of light physics, color theory, and optical illusions, it is possible to transform red into green in surprising ways. In this article, we will explore several methods for making red look green, including combining paint pigments, manipulating wavelengths of light, using afterimages, and leveraging color contrasts. While the physics of color remain unchanged, our perception of color can be altered with the right techniques. Read on to learn how you can turn red into green through science, illusion, and trickery of the eyes and brain.
Mixing Paint Pigments
One way to blend red into green is by mixing paint pigments. In painting, mixing colors follows the subtractive color model. This means that combining paints with different hues will subtract wavelengths of light and create a new color. To make green paint from red paint, you need to add a color that contains cyan and yellow wavelengths of light. Blue paint contains both cyan and some yellow. By mixing blue paint with red paint, the cyan cancels out the red wavelengths, while the yellow is preserved. This subtractive mixing produces a shade of green. The more blue paint added, the greener the mix will become.
For example, here is a simple mixing chart showing how red and blue paints blend to make green:
| Red Paint | Blue Paint | Resulting Color |
|---|---|---|
| 10 drops | 1 drop | Muddy brown |
| 5 drops | 5 drops | Dark green |
| 1 drop | 10 drops | Teal green |
As more blue is added compared to the red, the paint mix turns from a brown to a rich green. This demonstrates how two very different colors can combine to form green through precise paint mixing.
Manipulating Wavelengths of Light
Another way to turn red into green is by manipulating wavelengths of light directly. Red and green correspond to distinct wavelengths of visible light. Red has wavelengths around 700 nm, while green is around 500 nm. By starting with red light and selectively filtering out the red wavelengths, while preserving the middle wavelengths, you can produce green light.
There are a few ways to manipulate light wavelengths:
- Using prisms and diffraction gratings to split light into a rainbow spectrum, then blocking the red section of the spectrum.
- Placing red light through a green-pass optical filter that only allows green wavelengths through.
- Using LED light sources and adjusting relative intensity of red vs. green LEDs to create an overall green appearance.
For example, you could shine a red laser pointer through a prism, then place a piece of cardboard as a barrier in the red section of the rainbow. The remaining light that passes through will be mainly concentrated around the green portion of the spectrum, and appear green. Advanced color-changing optics can selectively filter wavelengths, essentially converting one color of light to another color.
Afterimages
The human visual system can also be tricked into seeing red as green through afterimages. Afterimages are an optical illusion that occurs after staring at a bright color for a period of time. The rods and cones in your eyes become fatigued and less responsive to that color. When you then look at a white surface, you will see an illusory afterimage in the opposite color.
To turn red into green using afterimages:
- Stare at a bright red image for 30 seconds or longer.
- Quickly shift your gaze to a blank white wall or piece of paper.
- You will see a ghostly green afterimage on the wall, opposite to the red color that was stared at.
This works because your eyes become desensitized to the red light. When they are then exposed to white light which contains red, green and blue wavelengths, the red is perceived weaker. This causes the white light to take on a greenish hue. Afterimages are a unique way of creating the perception of green out of red through fatigue of the eyes’ photoreceptors.
Color Contrasts
The color that appears on something depends heavily on its context and surroundings. Placing a red object on a green background can cause the red to take on a greenish appearance. This demonstrates the principle of color contrasts – colors influence each other when viewed together.
The red object reflects mainly red light to your eyes. However, some of the green background light is also reflected from the edges of the object. This adds a subtle green cast to parts of the red object. Additionally, after staring at the green background, your eyes become adapted to green. This causes the complementary red to seem shifted towards green when you view the object.
Some examples of using color contrast:
- Surround a red ball with green leaves – the red shifts towards green.
- Shine a red light through green transparent plastic – the light mixes and appears greenish.
- Paint a pink red stripe on a turquoise blue wall – the red stripe takes on a green tint.
Carefully controlling background colors provides a way to influence the apparent color of an object, like forcing red to appear green. Interior designers leverage this technique when selecting paints and fabrics for a room.
Conclusion
While red and green are fundamentally different colors in the physical sense, our visual perception is prone to illusions. By manipulating pigments, wavelengths of light, afterimages, and color contrasts, red can seem to turn green under the right conditions. Science gives us methods to create real green light from red light sources. But our malleable senses also provide shortcuts for faking the effect through contrast and fatigue of retinal cells. So while color itself doesn’t change, we can use these tricks to create the illusion of turning red to green.
