What is RGB: Understanding the RGB Color Model and the Fundamentals of LED Color Reproduction

One of the most significant milestones in display technologies was the invention of LEDs. These tiny semiconductor materials revolutionized the production of colored images by digital display systems. Particularly, this happened due to the production of color models. In this article, we explore the primary color model which is composed of red, green, and blue colors.

What is RGB?

RGB is an acronym derived by taking the first letters of three colors. These colors are also known as the primary colors from which digital displays reproduce the range of colors that we see. R stands for red, G for green, and B for blue.

Light can either be visible or invisible. The visibility of light is primarily influenced by what is known as the wavelength of light in the electromagnetic spectrum.

Chances are that you know the electromagnetic spectrum. If not, this is the range of frequencies in which light travels through. In other words, the light you see or doesn’t travel in a wave. The science of this travel is not quite relevant for this article.

In the electromagnetic spectrum, there is a range of colors that the human eye can see. This range, otherwise known as the visible spectrum, exists in the range of 380 to 700 nanometers. In other words, any light that falls between these ranges can be seen with the naked eye.

This wavelength also determines the color of the light produced. For instance, in the case of RGB colors, they have different wavelengths, hence the different colors.

The wavelengths of these primary colors are;

  • Red: 620–780 nm
  • Green: 490–570 nm
  • Blue: 440–490 nm

As you can see, these colors also have a range. This means that the colors have color intensity with low and high intensities. This is why you see faint shades of these colors when looking at an image on a display.

RGB as a Color Model

Color models use mathematical values to derive color by combining different colors. In simpler words, multiple colors get mixed together to produce another color. For instance, green and blue form the yellow color. This model is quite efficient and fast — factors that are attributed to the LED controller. 

The RGB color is not the only type of color model out there. One of the reasons why this is the case is because LEDs are capable of producing up to 16 million colors. Through color mixing technologies, the three colors, (blue, red, and green), are converted to a lot of colors.

The ability of an LED display to produce color depends on other factors such as the pixel density and type of LED. Therefore, these colors could exist in a wide range, what is known as color gamut.

Primary Colors of an LED Display 

LEDs are manufactured in red, green, and blue. These colors are controlled by the type of metal substrate from which the semiconductor is made.

Blue and green LEDs are made from indium gallium nitride (InGaN). This is mostly for micro and mini LED chips. Red LEDs on the other hand are made from aluminum indium gallium phosphide (AlInGaP).

These materials behave differently when excited by photons. That is why they produce different colors in the visible spectrum. These primary colors are responsible for producing the millions of colors that we see when looking at a display. 

Role of Human Perception in Interpreting RGB Signals

Your eyes also play a crucial role in color reproduction. As long as you have perfect vision, you can make out most of the colors that arise from the color mixing of an LED controller. 

The human eye uses photoreception to help the brain translate light waves. When light reaches the light-sensitive cells in the eye (rods and cones), it gets converted to electrical energy which is transported to the brain using the nervous system.

You could be surprised to learn that cone cells are also in three types; red, blue, and green. This is a more simplified description of the actual types. The types are categorized based on short, medium, and long light wavelengths.

When light enters the eye, it stimulates the three types of cones to varying degrees based on their wavelength. For instance, if the light has a long wavelength in the visible spectrum, the brain records it as red. However, the brain has adapted to seeing a wide range of colors from the continuous exposure it undergoes through life.

This color perception of the eye is known as the Trichromatic vision theory. It is a theory that says that the human eye only sees three colors, red, blue, and green. The other colors, also known as secondary, are produced by combining the wavelength of these primary colors.

Components of an RGB Color Model

The colors of the RGB model are also known as channels. Why channels? One of the reasons is that digital devices encode and decode color in a series of codes. Each primary color has a channel with a range of low to high-intensity colors.

The channels are also responsible for the color of the pixel in the image. This concept is best described in this article about bit depth.

Color channels of the RGB model have three channels. Of course, these channels are based on the three colors that make up this model. These channels are also responsible for the color reproduction of LED displays which happens via additive color mixing.

  • Red channel. This channel represents the intensity of red light in an image. During color mixing, it is responsible for producing a variety of warm colors such as shades of orange and yellow.
  • Blue channel. Blue represents the intensity of the blue light in an image. This is responsible for producing cool colors. 
  • Green channel. This one represents the intensity of the green light in an image. Green has a wide range of colors that it helps produce during the color-mixing process.

The RGB Color Model 

Another name that is used to refer to the RGB color model is an additive color model. This model was adopted from trichromacy — the human perception of colors. It was easy to invent this model since scientists had already established how eyes perceive color through this theory of trichromacy.

The RGB color model is responsible for sensing reproduction, and display of other colors in digital display systems. The RGB color model can be in an output or input device. These devices play a vital role in the perception of color by the human eye. 

Another characteristic of the RG color models is that the color production and sensing are dependent on the device used. This means that different devices reproduce different RGB values based on their software capabilities. This explains why colors look different on different devices. 

Foundations of Digital Color Representation

Color is encoded and stored as numeric values. This is important since computers understand and translate every component into digital values. Understanding this concept is crucial in your quest to understand what RGB is. 

There is one concept that is highly referenced when discussing color representation. The concept of pixels and their ability to store color. When you get in the weeds of the topic, you quickly realize that it is a complex phenomenon. However, we have to understand it if we need to comprehend the fundamentals of RGB color models.

Pixels that make up an image store values corresponding to color. These are the values that the digital display uses to translate the color information of the whole image. For example, in RGB color models, the pixels are assigned three values, each for its corresponding channel.

The 8-bit Color System

LED displays reproduce color using the 8-bit system. This means that each of the 3 channels has 8 bits of color, which results in a possible 256 color intensities. That means, for every color in the RGB model, there are possibly 256 shades of this color.

We are getting 256 because computers store values in 0 and 1s. Therefore, each bit has either a 1 or 0 value. Arithmetically, 2 power 8 is 256. With this, we can calculate the possible colors of an LED display by multiplying 256 by 256 by 256, which is the number of the primary colors. This gives us approximately 16 million possible colors.

A better way to think about the 8-bit color system using the 0 – 255 color scale. In this context, 0 means no light while 255 represents the highest intensity of that light. When 0 and 255 are added, we get 256 possible colors. 

The 8-bit system is also called 24-bit since 8 is multiplied by 3. This term is also used to refer to the bit depth of an image. 

Color Models in Computer Graphics

Each color model used in computer graphics falls in the category of either additive or subtractive. Let us discuss these two types in more detail.

Additive Color Models

The term additive refers to the technique used by the computer to generate color from the primary colors. This is why additive color is attributed to the RGB color model.

Additive colors are the results of the additive color mixing. These colors are known as additives since the mixing algorithm creates new colors from existing colors. For visual perception, the same concept applies, but this time what is being mixed is light.

Each color reproduced in this model has a mix of either 2 or 3 colors. Some colors are more complicated to reproduce. In these conditions, a color correction algorithm is applied to solve the artifact. 

The HSV/HSB model is another color model that is considered additive. It stands for Hue, saturation, and value/brightness. Rather than defining color based on light intensity, the HSV model describes color based on dimensions. This means the color is not based on how high or low the nanometers are in the visible spectrum. HSV is what enables us to create color gradients.

Subtractive Color Models

The other type of color mixing is known as subtractive. For the most part, this type of color mixing is applied to non-digital color outputs. They include paintwork. In subtractive color mixing, pigments, dyes, or inks are mixed manually to produce darker colors.

Technically, subtractive color refers to the process where another color is produced by subtraction of light wavelengths from an incident color. What you see is the color of the unabsorbed wavelengths of light.

In this model, red, green, and blue are regarded as secondary colors. For the most common subtractive color model, CYM, the colors cyan, magenta, and yellow are the primary colors that are mixed. 

Some of the common subtractive color models include; 

  • CMY and CMYK color models. This is an acronym that stands for cyan, magenta, yellow, and black. These colors overlay to create color, and this is the basis of subtractive color. CYM and CYMK are quite different models.

The major difference between additive and subtractive color is that the additive begins with no color while subtractive begins with white. The changes in light wavelengths are what produce the different colors we see.

Grayscale Model

In this model, color is defined using one component — its lightness. Specifically, the primary color in this model is gray. Therefore, all images that have different shades of gray are known as grayscale images, which are made from the grayscale model. 

Grayscale is different from monochromatic images. For the latter, it means that the image has only one color channel. For instance, an image could only have the red channel of the RGB color model and still be categorized as monochromatic. This model is used in applications where specific color information is unnecessary.

What is RGB Lighting?

Lighting is one of the primary uses of LED semiconductor devices. These light-emitting diodes (LEDs) are known for their luminescence, which is supported by their power efficiency, and range of light wavelength, among other features. 

RGB lighting is the use of red, blue, and green semiconductor materials to produce different lights. It is used mostly in LED strip lights such as COB and CSP LEDs.

Most RGB lights produce white light. This happens through the fusion of blue, red, and green lights to form a white light. In other cases, the light strip is made of a blue LED, which is then transformed into a white color by phosphor. 

There are three basic types of RGB lights;

  • Classic RGB: This is the standard RGB where the composition is only 3 LEDs; blue, red, and green.
  • RGB + W: This means that on top of the primary color diodes, there is a white diode used for pure white color.
  • RGBW. This type has four LEDs all in the same construction. It is different from the RGB + W since the white diode is not separate.

How RGB Lighting Works

RGB lighting applies the same principles used in digital display color formation. This explains why you see RGB lights produce so many colors. These LED luminaires are controlled with an LED controller. This is a device that has presets such as colors, intensities, and other settings you would need when controlling RGBs.

RGB lights have a diffuser that prevents the light from being too aggressive. In other words, it dims the color of the light produced. 

RGB lighting is over 90% more effective than incandescent bulbs. This efficiency is primarily due to the high lumen efficacy of these luminaires. Lumen efficacy is a metric calculated to tell how well and efficiently a light source produces visible light. This metric is calculated as a ratio of luminous flux (light brightness) to power consumed.

Additionally, these lights are super efficient because of one of the major properties of LEDs. It is known that LEDs emit light unidirectional light. This means that the light travels in a straight path. As a result, this reduces the need for reflectors and diffusers to manipulate light. These diffusers and reflectors can trap light inside the luminaire, reducing the brightness of the light.

Applications of RGB Lighting 

RGB lights can be used in a variety of applications due to their efficiency. If anything, there is a push for more people to replace their lights with LED-based lights for this particular reason. Since they consume less energy, the push is to adopt them as they preserve energy.

Some of the common applications of RGB lighting include;

PC components and accessories

The ability of RGB lights to produce many colors is a feature that makes them useful in decorative applications. You will find personal computers that are fitted with RGB lights for decorative reasons. These lights serve as a source of lighting and aesthetic appeal. Besides, they can be programmed to light up according to a script.

Lighting fixtures 

A light fixture is a lighting component that is attached to a specific location to provide illumination inside a room. A bulb mounted on the ceiling is a great example. These lights produce bright light, have uniform illumination, and generally function better than other lights.

Outdoor signage 

RGB lights are also used for messaging applications. Traditional outdoor signs that do not have LED displays can be fitted with RGB lights to make them visible in low-light conditions. Also, traffic lights in most countries use RGB light for lighting.

In this application, the RGB strip lights are lined inside the letters on a transparent board. Then, they can be programmed to light up in patterns when displaying the message on the signage. This is among the most common applications of RGB lights.

Backlighting

Although it is mostly a technology of the past, backlighting LCD panels were and still use RGB lights. One difference in this application is that only white light is produced. Also, these RGB lights need to be quite particular for optimal backlighting.

Advantages of RGB LED Products

The demand for RGB products is partly due to the many promising benefits it has over other forms of light. Some of these advantages include;

Energy Efficiency and Cost-effectiveness

As we saw earlier, RGB lights are able to convert the lowest watts into high lumens. This is what energy efficiency means. This is in contrast to incandescent lights which consume a lot of power and produce low brightness. 

Energy-efficient products are also cost-effective. While the initial cost of purchase could be high, the savings down the line make it even. To clarify, your energy bills will be reduced if you switch from traditional lights to LED lights. This also applies to displays made from RGB LEDs.

Enhanced color rendering and vibrancy 

This benefit applies specifically to LED panels. LED displays are quite efficient in color reproduction and representation. The additive color mixing technology that happens to the RGB color model is responsible for this.

Colors produced by LED displays look super accurate from what the brain expects. In fact, 8-bit systems are also known as true color systems. This is due to the ability to produce up to 16 million colors.

Dynamic color control and customization 

The ability to control and customize color in digital displays is something that is credited to the additive color mixing format. In particular, editing colored content to change or manipulate color is possible due to the features of RGB lighting.

Versatility and adaptability 

The versatility of RGB lights is seen in its ability to produce a wide range of colors. This is beneficial in many ways. First, it means that you are not limited to a certain number of colors. This is in relation to RGB lighting. However, the same can be said for RGB as a color model for LED displays.

For adaptability, we are referencing the wide range of applications that RGB lights fit in. Not only that, the conditions of use for RGB is wide. For instance, some RGB are water and dust-resistant, which makes them suitable for outdoor applications. 

Disadvantages of RGB LED Products

RGB is not without flaws. It has some setbacks that could influence your decision-making. Some of the major disadvantages of this technology include;

Limited color gamut 

Color gamut is the range of colors that an LED display can produce or represent. This property also takes into consideration true color. It means that the colors that a device can produce have to be as lifelike as possible. This is independent of the color-mixing properties of the display. The limitation of the gamut for RGBs is because of the hue and saturation of the primary colors. 

When we say that RGB has a limited color gamut, it means that the human eye can see more colors than what an LED display is able to reproduce. Therefore, this means that it has limited capabilities when it comes to color reproduction.

Inadequate Heat Dissipation

Heat dissipation is the removal of heat from high-heat to low-heat regions. This happens mostly in lighting conditions. 

RGBs produce heat alongside light. However, when compared to incandescent bulbs, the heat from RGB lights is quite minimal. Most RGB strip lights are either made using SMD or CoB techniques. These types of LED configurations have limited heat dissipation systems for effective thermal management.

Light Wavelength Gaps

One of the factors that control color reproduction is the wavelength of light. RGB is known to have limitations when it comes to the spectral distribution of light emitted by the RGB color channels. In other words, there is limited color accuracy and light spectrum coverage.

This is why you will find some artifacts developing when working with LED displays. Luckily, these issues can be corrected manually by experienced technicians.

Color inconsistency

Additive color mixing has one drawback; if executed incorrectly or under unfavorable conditions, it can lead to color inconsistencies. Some of the factors that contribute to this are the type of device, temperature variations, and calibration issues. These issues can be avoided by ensuring you are using high-end devices that are properly maintained. 

Conclusion

With the adoption of LED technology, color models such as RGB continue to dominate the industry. It has demonstrated superior reliability over its counterparts. Also, when used in lighting, RGB outshines other types of lights. Therefore, choosing RGB products will prove valuable now and in the long run.

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