Hello, everyone! Today, we’re diving into a fun question: What color is a banana? You might think it’s a simple answer, but it actually depends on the lighting. Let’s explore how light affects what we see.
Imagine you have red, green, and blue lights. When you shine all three on a banana, it looks yellow, which is what we usually expect. But if you use only red light, the banana appears red. With green light, it looks green, and with blue light, it turns black. Isn’t that interesting?
Originally, I wanted to show how different colors of light mix to create new colors. But this led me to discover something even cooler about how we see colors. I learned two important things: color vision is more amazing than I thought, and understanding it will change how you see colors forever!
Humans can see over a million colors, but let’s start with the basics. What exactly is color? We often say something is red or blue, but there’s more to it. Physics tells us that color is a specific wavelength of light. Isaac Newton showed this by using a prism to split white light into a rainbow.
In the visible light spectrum, violet has the shortest wavelength, and red has the longest. Machines can measure these wavelengths to identify colors, but our eyes work differently.
Let’s look at how our eyes perceive color. At the back of our eyes, we have special cells called cones that detect light. These cones send signals to our brain through the optic nerve. We have three types of cones, each sensitive to different light wavelengths: short, medium, and long.
If we only had one type of cone, everything would look black and white. But with three types, our brain can compare signals and see a wide range of colors.
Scientists used to think each cone sent a specific color signal to the brain, like a camera. But they found out it’s more complex. For example, yellow light can be absorbed by both long and medium cones, creating a perception of yellow.
When red and green light mix, they can also create the sensation of yellow. This is how screens display yellow by combining red and green pixels.
Our brains perceive colors in unique ways. Some color combinations, like blue and red, create purple. But we can’t see a color that’s both blue and yellow or red and green. These colors are opposites in our visual system.
Our brains use three channels to describe colors: redness vs. greenness, blueness vs. yellowness, and lightness vs. darkness. This helps us see millions of colors with just three types of cones.
Our brains are amazing at recognizing colors under different lighting conditions, whether it’s bright daylight or a warm sunset. Unlike cameras, our eyes and brains work together to interpret colors based on memories and comparisons.
The color of an object depends on its properties and the light around it. Our perception of color is a fascinating and complex process. Thanks for joining me on this colorful journey. Keep exploring and stay curious!
Gather red, green, and blue cellophane sheets. Shine a flashlight through each one onto a white surface to see how the colors mix. Try combining two or three sheets to observe the resulting colors. Discuss how this relates to the way light affects the color of a banana.
Use a prism to split white light into a spectrum of colors. Observe the rainbow created and identify the colors. Discuss how this demonstrates Isaac Newton’s discovery and how it relates to the concept of color as a wavelength of light.
Look at images of objects under different lighting conditions (e.g., daylight, sunset). Describe how the colors appear to change. Discuss how our brains interpret these colors based on lighting and previous experiences.
Use an online simulator to explore how the three types of cones in our eyes detect different wavelengths of light. Experiment with mixing colors and observe how the brain perceives them. Discuss the complexity of color perception.
Create a color wheel and identify opposite colors (e.g., red vs. green, blue vs. yellow). Use colored pencils or paints to mix these opposites and observe the results. Discuss why certain color combinations are perceived as opposites by our visual system.
Sure! Here’s a sanitized version of the transcript, removing any informal language and ensuring clarity while maintaining the essence of the content:
—
Hello, everyone. Today, we will explore the question: What color is a banana? The answer is that it depends on the lighting conditions. Here, I have red, green, and blue lights. When illuminated by all three, the banana appears yellow, which is not surprising since bananas are typically yellow. However, under red light, the banana looks red; under green light, it appears green; and under blue light, it looks black.
I initially intended to create a simple video demonstrating how different colors of light can combine to produce other colors. However, this led me to uncover more complex questions about color vision itself. I realized two key points: a) color vision is far more intricate and fascinating than I had previously thought, and b) to understand how it works, we will embark on a journey together. If you stay with me, I can assure you that you will never perceive colors the same way again.
Humans can differentiate between over a million colors, but let’s start with a fundamental question: What is color? For instance, what defines red or blue? We can point to objects and say they are red, but that does not fully answer the question. Physics provides another perspective on color. We did not truly understand color as a property of light until Isaac Newton demonstrated it by refracting white light through a prism, creating a rainbow.
In physics, color is defined as a unique wavelength of electromagnetic radiation within a specific part of the spectrum. Among the visible light spectrum, violet has the shortest wavelength, while red has the longest. A laboratory machine can determine the inherent color of light by measuring its wavelength. However, our eyes do not perceive color in the same way machines do.
Consider this example: two boxes, one containing a gray “X” and the other a green “X.” What if I told you both “X”s are actually the same color? This phenomenon does not deceive a machine, but it does deceive us, indicating that there is more complexity involved.
Let’s briefly review the anatomy of the eye. At the back of the eye, in the retina, there are specialized photoreceptor cells called cones that absorb photons—tiny units of light—and transmit electrical signals through the optic nerve. We do not have individual receptors for all the millions of colors we can perceive; instead, we rely on three types of cones, each sensitive to different ranges of light: short, medium, and long wavelengths.
If we had only one type of cone, a photon of one color would send the same signal to our brain as a photon of another color, resulting in a black-and-white perception. However, by comparing the signals from the three types of cones, our visual system can distinguish individual colors.
Scientists once believed that when an image reaches the retina, each cone sends its distinct color signal to the brain to create an image, similar to how a camera operates. However, they discovered that this would limit the range of colors we could perceive, which does not account for all the colors we actually see.
This complexity arises because the same color of light can be absorbed by multiple cones. For example, yellow light, with a wavelength of around 580 nm, can be absorbed by both the long-wavelength cone and the medium-wavelength cone. The specific cone that absorbs a photon depends on probability. As more yellow photons enter the eye, both cones register the light, leading to a combined perception of yellow.
Now, consider what happens when red and green photons enter the eye. Both colors can be absorbed by the long or medium cones, resulting in a similar perception of yellow. In fact, this is what occurs on your screen right now, where light from red and green pixels combines to create the sensation of yellow.
Returning to our banana, it reflects green and red light while absorbing blue light, which is why it appears black under blue light. However, under red and green light, the banana appears yellow because it reflects both colors to our eyes.
When we observe an object and perceive a certain color, we are actually seeing a combination of various colors of light reflecting off of it, often without realizing it. Our visual system interprets these signals by weighing certain colors against one another.
An Austrian scientist noted that certain color combinations simply do not exist. For example, we can perceive blue and red together as purple, but we cannot visualize a color that is simultaneously blue and yellow. Similarly, while we can perceive red and yellow together as orange, we cannot perceive a color that is both red and green. To our visual system, blue and yellow, as well as red and green, are opposites.
Our brains perceive the color spectrum differently than we might expect. Each color can be described by its position on three channels: redness versus greenness, blueness versus yellowness, and lightness versus darkness.
To illustrate this, consider a visual exercise with a flag. As you focus on the center, allow your eyes to relax. After a few moments, I will remove the flag. Do not move your eyes; just observe what happens. You may notice afterimages, where the colors you saw are replaced by their opposites. This demonstrates how our visual system treats certain colors as opposites, where the presence of one color diminishes the perception of its counterpart.
We can observe this phenomenon in the shadows cast by colored lights. When overlapping blue and red lights, we see a bluish-red. When green and blue overlap, we see a greenish-blue. However, when red and green overlap, we only perceive yellow, which is the opposite of blue.
This system of four primary colors, processed through three channels, allows us to distinguish millions of hues with just three types of color-sensing cells in our eyes. Furthermore, once these signals are processed by our brains and compared with our memories, we can accurately identify colors under varying lighting conditions, whether in bright daylight or warm sunset.
Our brains do not function like computers, and our eyes do not operate like cameras. While cameras can mathematically integrate red, green, and blue light to produce a direct value for each pixel, our perception of color relies on the combination of three different cells and the comparison of four colors across three channels.
In conclusion, the color of an object is determined by its inherent properties, but our perception of color is also influenced by various factors, making it a complex and fascinating subject. Thank you for joining me on this exploration of color vision. Stay curious!
—
This version maintains the informative nature of the original transcript while ensuring clarity and professionalism.
Color – The property of an object that depends on the light it reflects and how it is perceived by our eyes. – The color of the apple appeared red because it reflected red light to our eyes.
Light – A form of energy that travels in waves and can be seen by the human eye. – Light from the sun helps plants grow by providing the energy they need for photosynthesis.
Vision – The ability to see, which involves the eyes and the brain working together to interpret light signals. – Our vision allows us to see the world in vibrant colors and shapes.
Wavelength – The distance between two consecutive peaks of a wave, such as light or sound. – Different colors of light have different wavelengths, with red having the longest and violet the shortest.
Cones – Photoreceptor cells in the retina of the eye that are responsible for color vision. – Cones in our eyes help us distinguish between different colors in bright light conditions.
Brain – The organ in our body that processes information received from the senses, including vision. – The brain interprets signals from the eyes to help us understand what we are seeing.
Perception – The process by which the brain interprets sensory information to form an understanding of the environment. – Our perception of color can change under different lighting conditions.
Spectrum – The range of different colors of light, arranged by wavelength. – A rainbow shows the spectrum of visible light, from red to violet.
Colors – Different visual perceptions that result from the way light interacts with the eyes. – The colors of the sunset ranged from deep orange to soft pink.
Signals – Messages sent by the eyes to the brain to be interpreted as images. – The eyes send signals to the brain, allowing us to see and understand our surroundings.
