Why Do Objects Have Color or Appear Different Colors?

Top view of colorful Lego bricks

The world is full of color, but few people stop to wonder why and how. We’re used to the way we see colors, so we rarely go out of our way to question why they look the way they do. Yet, the process for how objects obtain color is complex and fascinating.

Not all animals see color the same way we do, either. Most mammals see fewer colors than us, while certain insects can see colors we can’t.

The colors we see have to do with light and our eyes working together. Let’s take a closer look at how the colors around us exist.

Light shining through prism

Why Do Objects Have Color?

Objects have colors because they’re reflecting certain wavelengths of light more than others.

Every object is made up of different materials, including atoms and electrons. The makeup of an object causes it to do different things when light hits it, such as reflecting or absorbing wavelengths that we perceive as colors. When wavelengths reflect off an object, that’s what causes it to appear as a specific color.

Here are a few things that can happen when light hits an object:

  • Reflection – Most objects will reflect light to some extent. Objects that have more free electrons in them will be more reflective because the electrons vibrate to send light out of the object at the same frequency it came in. Metals and mirrors are the most reflective objects. When light reflects off objects, the wavelengths that shine back at you are the ones that determine the color of the object.
  • Absorption – Light wavelengths can also be absorbed into some objects. Most of the time, some wavelengths get absorbed and some reflect, but opaque objects will absorb most or all of the light. Items that absorb all wavelengths will look black.
  • Transmission – Sometimes, the light’s energy will be significantly higher or lower than the electrons inside, preventing them from reflecting or absorbing light. Instead, the light will pass through the object without changing its appearance. Objects that go through transmission are transparent, such as glass.
  • Refraction – Refraction occurs when the wavelengths of light are redirected. When light passes through the item, it may go through it, but it will look bent. Some examples are a glass of water or a transparent triangular prism. This action is the least common occurrence on this list.

All these actions influence what color an object looks like, but if you’re looking at an object that’s a color of the rainbow, that’s because some reflection is going on. Objects only have color to us when light hits them, which is why everything looks black or gray when the lights are off.

Objects have color because of the wavelengths that reflect off them, along with how our eyes and brains perceive them. Different colored objects have different processes going on.

How Do Objects Appear as Different Colors?

Wavelengths absorbing and reflecting on different colored objects

On the visible spectrum, there’s a range of wavelengths that appear as different colors to us. The longest, most stretched-out wavelengths are red, and the shortest, most frequent wavelengths are violet. In between, you’ll find the other colors of the rainbow, including orange, yellow, green, cyan, and blue.

When light hits an object, those wavelengths are either absorbed or reflected based on what the item is made of. For example, if light shines on a banana, all colors except yellow will be absorbed into the fruit while yellow reflects back toward our eyes. Thus, the banana looks yellow.

If all wavelengths are reflected, the object looks white. All colors of the rainbow combined in lights make white. That’s why the sun and light bulbs look white even though they can send all the colored wavelengths to objects.

If all the colors of light get absorbed, the object will look black. As mentioned earlier, if the wavelengths go through transmission or refraction, the item will be see-through.

These rules are only true if a white light is shining on the object. If a colored light is used, the results will differ. For example, if a white light is shone on a red apple, it’ll look red because red wavelengths will reflect while everything else gets absorbed. However, if only a green light is shone on the apple, it’ll look black because green will be absorbed, but there’s no red to reflect.

The Eye’s Role

Eye seeing colored visible light

After the wavelengths reflect off the object, they’ll enter your eyes to help you process what color you’re looking at. The eye has millions of cells that are sensitive to light. Some of those cells are known as cones and others are rods. They’re named after how they’re shaped. Cones and rods are found in the retina, and they work together to help you see color no matter how light or dark the space around you is.

Rods are more sensitive than cones, so they help you see during dim lighting. Most of the colors rods help you see are close to black and white. Cones can handle higher amounts of light intensity, so they can help you see colors under bright lights. You need both cones and rods to fully experience the colorful world around you.

What About Colors Not in the Rainbow?

Of course, we can see a wide range of colors that aren’t part of “ROY G BIV.” For many colors, we’re seeing more than one wavelength to make up that color. For example, blue and green in lights make cyan, so to see a cyan object, both green and blue will reflect back at us while all the other colors are absorbed.

However, not all colors can be mixed that way. For instance, you’ll never see a brown light, and there’s no way to mix brown using other lights. Yet, you can see brown objects. The same is true for other dark colors. The reason is that our eyes don’t work alone, but instead, they also rely on our brains for context.

In most cases, brown objects are just orange lights that our eyes are interpreting as brown. If the lights around the orange are brighter, it might look more brown. If the orange is producing more light than the colors around it, it looks orange. This is the case for many darker colors, such as gray, navy blue, and mustard yellow.

So, objects have colors because of the wavelengths they absorb and reflect but also because of how our eyes and brains perceive the wavelengths.

Mixing Colored Lights

Mixing colored lights on projector

Wavelengths of light mix to give us unique colors, but did you know that mixing lights is much different than mixing other art mediums like paint?

Mixing lights uses the RGB color model, which is a form of additive mixing. In RGB, the primary colors are red, green, and blue, so they differ from the red, yellow, and blue you likely learned in early art classes. When mixing light through RGB, the colors get lighter rather than darker.

When an equal amount of red, green, and blue are combined, they make white, just like all the light wavelengths do. The secondary colors of RGB are yellow, cyan, and magenta. Some tertiary colors include orange, violet, and rose. Mixing colored lights can show us how reflecting multiple wavelengths helps our eyes perceive objects of different colors.

How Do You Mix Colored Lights?

When mixing paint, you swirl the two paint colors together until they create a new hue. Yet, if you have two colored lights, all you have to do is shine one color on top of the other and they’ll make a new color. Changing the brightness of each color can influence how the color turns out.

You can either use two colored lights or you can create any color on the spectrum by combining red, green, and blue at different brightnesses.

Can Any Animals See Colors the Same as Humans?

Closeup of chimpanzee face with eyes looking directly at the camera

As mentioned earlier, some animals can see more or fewer colors than we can. For example, dogs can’t see red and green well, but dragonflies can see more colors than we can. So, are there any animals that can see colors the same as humans?

Primates are the closest-related animals to humans, so they’re also the ones with the most similar color vision. Many primates, such as apes and chimps, can see the same colors we can. Primates that don’t share as much human DNA have slightly worse color vision, struggling to see some reds and greens. Most mammals are colorblind to red and green.

Birds and insects are believed to see more colors than humans, but it’s hard to compare because insects have different types of vision than people. Most animals see and interpret colored objects like humans would, except with fewer colors. Insects, arachnids, and other creepy crawlies have compound eyes that cause them to process colors differently.

Admiring the Colorful World Around Us

Most people see the world in many colors, but we don’t stop to think about the reasoning behind it. A lot is going on between light, objects, our eyes, and our brains. It’s hard to believe there are so many steps that lead us to processing items as the colors they are.

So, now that you know what goes into giving objects colors, it’s a good opportunity to relax and appreciate the many colors of our daily lives, especially since most animals do not see the world the same way we do.