Bit Depth: The Core Aspect of Digital Imagery and Its Impact on Visual Perception of Color

Pixels are among the major elements that influence the visual perception of a digital image. These pixels convey vital information known as bit depth, among other technical data. It is essential to learn about this information since it comes in handy when choosing display panels. In this article, you will learn about bit depth and how it impacts image color.

What is Bit Depth?

Bit depth is defined as the number of bits that define the pixel in an image. We will learn more about bits and colors when looking at the fundamentals of bit depth. 

Bit depth stipulates the range of colors that an image can carry. In other words, how many colors can the naked eye identify with little to no ambiguity? The quantity of these bits determines the range of colors visible. That means a high bit depth results in a clear and colorful image. In the display world, this level of coloration is referred to as true color. 

The human eye is able to clearly perceive up to 10 million colors. Most modern displays, especially LED displays, can show up to 16 million colors. This means that the color of an image with enough bit depth will be reproduced as it is on the display.

Colors have shades. This means that one color, for instance black, has a dark and light hue. For the naked human eye, it would be hard to identify these shades for multicolor images. The pixels of multi-color images have a high bit depth. However, monochrome images, usually have very little bits. It could be as little as 1 bit. A 1-bit image has black and white shade. 

Throughout the article, we will reference terms such as bits, binaries, primary colors, depth, and other technical parameters to help you understand this terminology. It will soon become clearer that bit depth is not as complicated as you would have thought.

Fundamental Concepts of Bit Depth 

Technical concepts like bit depth need a lot of context to understand. This context can be built by looking at the building blocks and their definitions. Let us explore some of the major building blocks to help us paint a better picture (no pun intended) of bit depth.

Bits and colors

The term binary can be used to define bits. Binary means two. In other words, on and off. In the context of shades of color, bits are considered binary. For every bit, there are two shades of color. As the bit amount (bit depth) increases, the shades increase in the same multiple. 

To enumerate, 1 bit of color has two shades — black and white. Two bits have four shades. The shades are black, white, blackish-gray, and whiteish-gray. For monochrome images, these shades will continue increasing with every multiple bit. 

When describing bits, shades of color are assigned values. For instance, black is assigned the value 0, and white is assigned 255. An image pixel that has a color ranging from 0 to 255 is considered a grayscale image. These images have 8 bits in every pixel. 

You might be wondering what about other colors such as red, and yellow. These colors are defined by the concept of color channels and models. 

There are generally two major color channels;

  • RGB channel (primary colors) – These are primary colors in the visible spectrum. They are used in computer graphics since they are more accurate.
  • CYMK channel – Used for print media.

Other channels that are not so common include HSV and YIQ. These two deal mostly with how humans perceive color rather than actual color physics and reproduction.

Primary colors (RGB) 

Red, Green, and Blue are considered primary colors of the visible spectrum. Primary in this case means that other colors, such as yellow, orange, and brown, are derived from a mix of the RGB color model. 

As a side note, LED displays are based on the RGB model. This helps LED displays like RGB video walls to showcase accurate colors of images. This is what contributes to the vibrance, brightness, and contrast seen in these displays.

Each color in the RGB model represents the intensity of that color information inside the image pixel. This intensity is indicated by a value which ranges from 0 to 255. Therefore, when added together, it means that each channel has a possibility to produce 256 colors. The 0 to 255 range applies to the 8-bit color channel system only. 

An 8-bit LED display will have the possibility to showcase 16 million colors of a digital image. This value is calculated using this formula; 

256^3 = 16,777,216

This system of assigning color channel values is effective at identifying the possible colors that a display can reproduce. Color reproduction software used in digital image generation has these values when creating pixel data and the display image decoder picks them up for translation during signal broadcasting.

Additive color and Subtractive color models

Color model is another concept related to color that you need to know. The two most common color models known are additive and subtractive color. In this context, the phrase color model is used to describe the relationship between color and medium of expression. More specifically, the color of the image in relation to the medium used to display the image. 

Images can either be printed or displayed on a digital medium like a screen. For digital images, the color technicalities are described by the additive model. On the other hand, the subtractive model is used to describe print media. This will become clear in a moment.

Additive models use RGB colors to produce various colors of digital imagery. This is because the RGB channels are the primary colors used for digital image color production. 

Color mixing is the term used to describe the color reproduction of two intensities of primary colors. Some of the common mixes are; 

  • Cyan = Green and Blue
  • Magenta = Red and Blue
  • Yellow = Red and Green

The intensity value of the colors being mixed has to be 255. In other words, for the resultant color to be created, the intensities of the colors being mixed have to be at the highest. This mixing happens automatically at the subpixel level for high-end displays. 

In the subtractive color model, the CYMK channel is used for color reproduction. Colorants like paints and inks are used for color mixing to produce different colors. 

The CYMK channels contain cyan, magenta, yellow, and key (black) colors. These colors are mixed either manually or automatically to regenerate new colors. Since colors like cyan, magenta, and cyan are non-primary colors, the CYMK model is not as accurate as RGB. Therefore, you might find colors have different hues and saturation when printed.

Bit depth and color gamut

The term color gamut is used to describe the range of colors that can be reproduced by a digital display system. This means the range of colors, based on RGB channels, that are perceptible by the human eye. 

Bit depth and color range are related in many ways. One influences the other. However, it is important to note that bit depth is associated with the color accuracy of an image, while color range or gamut is tied to the color reproduction features of a display. That said, both are used in the same context to show the relationship between the accuracy of color perception.

As of the publishing of this article, the highest bit depth known was 48 bits per pixel. Such a high bit depth per color channel results in insanely huge color ranges. Specifically, a 48-bit system will reproduce 281 trillion colors. This number is way beyond what the current display systems can showcase. Meaning, that some of the colors will be misrepresented or lost in the reproduction.

Displays that have a wide color gamut are able to accurately display the encoded colors of high-bit depth images. Images with high bit depth are known to have high bits for each primary color channel. This results in visible differences between colors that would otherwise seem similar.

Shades of Color

Color is influenced by the intensity and brightness of light. Every color has different shades, which are informed by variations in the brightness and intensity of the light from the medium. For this to happen, the hue and saturation of the color have to remain constant. 

The best way to understand shades of color is to consider the greyscale image. Gray is a color between black and white. Therefore, when looking at a grayscale image, you will notice different shades of gray. This example can help you understand how bits define the overall color of an image.

To put this into context, a 1-bit grayscale image will have two shades of gray, while an 8-bit will have 256 shades of gray color. Therefore as you can see, the theory holds. Meaning, that the higher the number of bits, the higher the color range, and vice versa. This can be demonstrated by comparing a low and high-bit image.

Comparing low vs. high-bit image

The bit depth of an image is influenced by several factors. One of these factors is human perception. While vision is not universal, there are tell-tale signs that the majority of the human eyes can pick up to differentiate low and high-bit images.

This image shows the difference between low and high-bit images. The image on the left has 1 bit per pixel, which results in two shades of color. The 8-bit image, however, has more shades of color due to the high bit depth.

Key Aspects of the Science of Color 

Color depth, another word for bit depth, is studied under calorimetry. This field of study is also known as color science. It is concerned with several aspects that relate to how color is produced, perceived, transmitted, and interpreted by mediums. Let us learn about some of the key concepts of color science.

Color Physics

The physics of color is quite interesting but at the same time complex. You see, color cannot exist without light. Therefore, you need to understand light to understand the physics of color.

Light is electromagnetic radiation of specific radiation wavelengths in the visible spectrum. These radiation wavelengths are responsible for how the human eye interprets light. Other factors that come into play for light to be seen as color include additive color mixing, perception, and a part of the eye called the cone.

The length of the electromagnetic wave produced by light determines which colors the light-sensitive cells in the eye will see. For the primary colors, RGB, red has the longest while blue has the shortest wavelength. Therefore, red is much more visible than blue and green.

The brain interprets information it is fed by the long, medium, and short cones in the retina into a specific color. When it comes to perceiving secondary colors, these cones “mix” the colors using the same principle used in additive color modeling.

Color Reproduction 

Display technologies are equipped with software and hardware to translate color values contained in the bits into actual colors. This process is called color reproduction. Different displays will have varying degrees and mechanisms of color reproducibility. 

LCD screens for instance have a color filtering layer in their structure. This filter works with the backlight components, in most cases LEDs, to allow specific colors to penetrate. This reproduction technique is effective in displaying accurate color as encoded in the pixel of an image.

Color Psychology

This is a branch of psychology that deals with how color affects human behavior. It is based on the realization that humans respond differently based on a certain color. Over the years, this concept has been used widely in different situations based on the expected responses.

Given that color has such a huge influence on human psychology, aspects like bit depth are quite crucial in mass media. Variations, intensity, accuracy, and consistency need to be observed when dealing with color. By doing so, there is less likelihood that the wrong emotion or response will be triggered accidentally.

Color Perception

Otherwise known as color vision, this concept in color science entails the human perception of different colors. Think of it as the biological processes that happen between the eye and the brain when color is presented.

Perceiving color depends on factors like;

  • Health of the human eye
  • Wavelength of light
  • Brains ability to interpret color
  • Environmental factors and conditions

These factors dictate what color you see. For instance, conditions like color blindness affect the ability of a person to accurately tell mixed colors apart. Such a condition ends up limiting the person to primary colors which are more distinct.

Relationship Between Color and Light 

Light and color are inseparable elements. When discussing the physics of color, we briefly mentioned the relationship between color and light. Let us maintain the theme and explore the concept further.

Color occurs as a result of light. This explains why it is almost impossible to see anything in the dark because the photosensitive receptors in the eye are not stimulated. All this ties back to bit depth as well. Wavelength is the major component of light that influences color. 

How wavelength of light determine its color 

As we learned earlier, the length of the radiation wavelength determines the color we see. There is another concept you need to learn here. The length of the radiation wave also determines the intensity of the color. This means the most visible colors have high intensities according to the color receptors in the retina.

The electromagnetic spectrum is quite wide. In this spectrum, there are wavelengths that are too low that they do not produce enough light that can be seen by the human eye. For instance, ultraviolet rays are invisible since their wavelength is as low as 100 – 300 nm. On the other hand, the wavelength of the visible spectrum ranges between 400 – 800 nm.

The Significance of Bit Depth

So far, we have discovered that the more the bit depth an image has, the higher the range of colors it can store. But what does this actually mean for the everyday person? This question provokes us to think about the significance of bit depth.

Bit depth is significant in the following ways;

  • Color accuracy: In graphics design, color accuracy is critical because it helps avoid inaccurate color representation. This can only be achieved if an image has enough color depth in its pixels to hold color information.
  • Post-production: Images that have a high bit of depth can be edited without having to worry about losing information or introducing artifacts. 
  • Dynamic range: This refers to the range of darkest and lightest values of a color. If an image has few bits per pixel, it will not have a lot of shades for a single color. Therefore, the whole image will have a limited dynamic range.
  • Emerging technologies: Bit depths have started becoming a concern as technology improves. Features like HDR require images to have high bit depths for them to work.

Those are among the significances that demonstrate the importance of bit depth. With that, you can make better decisions about which display panels to purchase.

Impact of bit depth on the color of an image

The color of an image is directly proportional to its bit depth. Still, color has several elements that go beyond what is seen. While some of these elements are not influenced directly by bit depth, it serves as a strong basis for them.

Some of the aspects of color that are impacted by vit depth include posterization, gradation, and smoothness. Low bit depth tends to amplify them while high bit depth ensures that they are unavailable. Posterization, for instance, is the resulting artifact that leads to a visible barrier between two colors in images with low bit depth. 

These aspects can affect the overall visual quality of an image. They can make an image appear blurry, distorted, and inaccurate. Therefore, this reinforces the theme we have maintained that low bit depth has negative implications.

How Bit Depth Influences Color Gamut and Contrast

We have mentioned color gamut and contrast a few times but we have not quite captured the concepts comprehensively. More importantly, we have not explored how they are influenced by the bit depth of an image. Let us do that now.

Color gamut

Displays such as LEDs are capable of reproducing a wide range of colors. This is primarily because of the RGB semiconductor devices that are the basis of LED technology. This concept is also known as color gamut. It refers to the ability of a display to show a wide range of colors as encoded in the bits of an image.

Color gamut is an important feature since it controls how much color information of an image can be perceived. Normally, a display would be able to show limited colors if the image itself is encoded poorly. However, features such as color gamut have supporting algorithms that correct artifacts and other hindrances that affect image quality.

Contrast 

This is another feature that exists in both image and display technologies. Since bit depth is tied to digital imagery, contrast is a determinant in the visual quality of an image. 

By definition, contrast is the difference of illumination seen in different objects. In other words, how clearly is it possible to distinguish two colors of an object? Contrast is important since it helps you see the fine details in an image. 

Bit depth and contrast are related in that the higher the bit depth, the more the contrast in the image. This makes sense because more bits mean that the image pixels can store a wide range of color information. Subsequently, this means that the image processor can be able to pull specific color shades, thereby contributing to more contrast between colors.

Visual Quality of LED Display and Bit Depth

LED displays are superior in the display technology market. Their high pixel densities and color accuracy are some of the features that make them superior to their counterparts. These features ensure that they can accurately display content without losing details.

Content with high bit depth benefits a lot from displays such as those made from LEDs. The processors in these types of displays are able to reproduce content as it was encoded. An example of such a display is the 8-bit LED display. This display has the ability to reproduce up to 256 possible color shades of a particular color channel. 

Image generation tools such as graphic design software are able to produce accurate color images due to the sophisticated color value assigners available. However, this would be worthless without powerful displays to bring out these colors as they were created.

Color Reproduction of Display Technologies

Reproducing color happens automatically for digital imagery. At the basic level, color reproduction happens in the pixel. These pixels are controlled by internal systems that ensure that the color is correct and related to reference signal data.

This means the quality of the LED chips used in a display has a huge impact on the color reproducibility of the display. The best way to demonstrate this is to look at the visual experience of OLED vs. micro-LED displays.

OLED displays have organic LEDs which are susceptible to issues like burn-in effects, image retention, and lack of color accuracy. These issues will lower the image quality of an image regardless of its bit depth.

Micro LED displays on the other hand are made using inorganic LED chips. These chips are less likely to lead to some of the issues seen with OLED displays. Therefore, images shown on micro-LED displays are much more accurate, vibrant, and life-like.

Benefits of Learning about Bit Depth

Concepts explained in this article will benefit a wide range of people. You could either be curious about the industry lingo, looking for industry-specific knowledge, or a casual reader. Either way, you will benefit a lot from the article. Let us look at some of these benefits closely.

Understand industry terminology 

Display technology is an industry with several terminologies that can be quite confusing and intriguing. As such, getting acquainted with some of the terms can help you stay ahead of the curve. This is particularly important if you are in the business of dealing with display panels and such likes.

Make informed decisions

This is a follow-up to the previous advantage. With enough knowledge about industry-specific lingo, you are in a better position to make important decisions based on data.

Decisions such as the type of display to purchase require you to weigh several options. Without proper and helpful information, you can get overwhelmed and have a difficult time deciding what works for you.

Prioritize visual quality 

Color information is essential in defining the quality of an image. Therefore, aspects of color like bit depth will become critical when deciding what is important. Visual quality is something that most consumers care about. Now that you know this and how bit depth fits in the puzzle, you understand why visual quality matters.

Conclusion

Technical concepts like bit depth require an in-depth look for you to understand them comprehensively. This article has covered some of the major ideas that contribute to a better understanding of the concept. You are now more informed about how bit depth influences the color perception of digital imagery.

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