What is Delta E? And Why Is It Important for Color Accuracy?

What is Delta E?

As you’re looking for a high-end monitor, you probably find yourself wondering, “What is Delta E?” In short, it’s a measurement of how much a displayed color can differ from its input color. A lower Delta E means better color accuracy. How good is good enough? It depends on your needs (and we give a handy guide to Delta E values below).

So you can learn more about Delta E below. Or view our selection of professional-grade ColorPro monitors.

In the consumer and business electronics space, there’s no shortage of terms to confuse shoppers. We’ve previously discussed a handful of topics, such as lumens and resolution. However, one of the more abstract terms you can encounter in the space is Delta E (also commonly written as ΔE, or E*).

Delta E is a measure that plays a significant role in evaluating color accuracy. Creative professionals such as photographers, video editors, and graphic designers should all pay attention to this standard as it’s an essential part of choosing a professional-grade monitor.

Although creative professionals need to understand the meaning of Delta E; given the complex nature of the topic, it’s easy for the definition to get lost in translation. With that in mind, let’s take a closer look at what Delta E is and how you can use the metric to make an informed decision when purchasing visual equipment.

What is Delta E?

Delta E is a standard measurement — created by the Commission Internationale de l’Eclairage (International Commission on Illumination) — that quantifies the difference between two colors that appear on a screen. When you’re shopping for a projector or digital display, you’ll want to find a device with a Delta E level that is as close to zero as possible.

Delta E levels are the difference between the displayed color and the original color standard of the input content. Lower Delta E figures indicate greater accuracy, while high Delta E levels indicate a significant mismatch.

The “E” in Delta E stands for “Empfindung,” which is the German word for sensation. Delta is a Greek word that stands for the incremental change of a variable. As a whole, the term Delta E means a difference in sensation.

Delta E is measured on a scale from 0 to 100, where 0 is less color difference, and 100 indicates complete distortion. As explained in this guide by Zachary Schuessler, standard perception ranges are as follows:

  • <= 1.0: Not perceptible by the human eye
  • 1-2: Perceptible through close observation
  • 2-10: Perceptible at a glance
  • 11-49: Colors are more similar than the opposite
  • 100: Colors are exactly the opposite

Why is Delta E Important to Professionals?

It’s essential for professionals to understand the meaning of Delta E because as explained earlier, this metric is the foundation of color accuracy. It’s a single figure that can be used to quantify whether a display correctly shows colors, rather than relying on subjective views.

Going beyond aesthetics and viewability, when a person has a collection of monitors with low Delta E amounts, it means that they can perform high-end tasks such as editing graphics and videos, across multiple monitors, without any noticeable distortion.

Delta-E-Measure-Monitor-s

How to Calculate Delta E in Color

Delta E (the total color difference) is based on delta L*, delta a*, and delta b* color values, all of which provide a complete numerical descriptor of the color in a rectangular coordinate system. The meanings are as follows:

  • dL* represents a lightness difference between the sample and standard colors.
  • da* represents the difference in redness or greyness between the sample and standard colors.
  • db* denotes blueness-yellowness differences between the sample and standard colors.

In the case of the levels mentioned above, the higher the value, the greater the difference in that dimension. Since Delta E revolves around three core elements, it’s easier to calculate than you would expect.

You only have to square the difference between each of the L, a, and b values; then add them together; then take the square root of the sum. The mathematical expression of the formula, however, is a bit more intimidating:

CIE76 color difference formula
Equation courtesy of http://zschuessler.github.io/DeltaE/learn/

This formula provides significant insight into the difference seen between two colors. A more precise formula is Delta E(94). The formula for Delta E(94) is significantly more complex than the standard Delta E formula, which is why it is beyond the scope of this article.

Why You Should Choose a Monitor with Delta E of ≦2

When shopping for professional electronics equipment, you will want to purchase devices with Delta E levels that are less than two, since, at that point, the human eye sees the displayed colors as they were originally intended to be shown.

In general, top-of-the-line displays, that are priced significantly higher than traditional devices, have Delta E levels of one or less. It’s impossible to get down to zero, however. Next to that, however, are the high-end, high-quality devices that have a Delta E of ≦2.

How Do You Measure Colors?

A common question that comes up when people discuss Delta E levels is how to measure colors precisely. While you can use scales and rulers to measure weight and size, light is a bit more ambiguous. Depending on the color space you use, there are different formulas.

In terms of actual hardware to measure light, you can purchase a colorimeter. They measure light through a set of XYZ filters, which are optical filters designed to mimic the optical characteristics of tristimulus (XYZ) values. Tristimulus values are the foundation of color language and are also referred to as the CIE color system.

What is CIELAB?

CIELAB is a color space that is also known as “CIE L*a*b*” or simply “Lab color space.” Created in 1976 by the International Commission on Illumination, the value expresses color as three values. Hunterlab has an extensive article on the topic, but the general elements are as follows.

  • L* represents lightness, with 0 being a perfect black, with 0% reflectance or transmission. A rating of 50% indicates a middle gray, while a 100 rating indicates a perfect white. This indicates 100% reflectance and perfect clarity.
  • a* represents redness-greyness of the color. Positive values of a* are red, while negative values are green. A level of 0 is neutral.
  • b* denotes yellow-blueness of the color. Positive values of b* are yellow, while negative values are blue. 0 indicates neutrality.

Since CIELAB is measured across three dimensions, there’s an infinite number of color possibilities. The CIELAB model also follows perpetual uniformity. This enables the standard to better approximate human vision. This provides a significant advantage over the RGB and CMYK color standards, which are less precise.

The precision provided by CIELAB is at a level where it requires significantly more data per pixel, compared to RGB and CMYK standards. Since the gamut of the standard is higher than most computer displays, occasionally there is some loss of precision; however, advances in technology have made such issues negligible.

The CIELAB model is device-independent meaning that the color definitions are developed independently of how they are created or displayed. The most common application of this color space is when graphics for print need to be converted from RGB to CMYK.

Since the lab space is fully mathematically defined, the CIELAB is copyright and license-free. It’s also entirely in the public domain, meaning that it’s completely free to use and integrate into your projects.

What is Delta E? You'll need to know when working with colors.

Other Color Spaces of Interest: RGB and HSV

Although CIELAB is one of the most common industry standards, it’s far from the only major color space in the industry. The RGB and HSV color spaces are worth discussing here because they also play a significant role in digital graphics quality.

The RGB color space, short for red-green-blue, is an additive color model, which means different proportions of those lights can be used to produce any color. This color model was created specifically for display purposes, such as screens and projectors.

Many displays are comprised of red, green, and blue lights. When seen from afar, usually two feet or further, then the colors merge. When examined closely, the human eye is able to see different sources.

Although RGB is an effective standard, computer graphics professionals found it difficult to use the standard to create sophisticated color shades. That’s why the HSV color space was created. It’s a more convenient representation of the RGB color space.

HSV stands for hue, saturation, and value, and provides a more accurate color perception level compared to other standards. This is because the color space is comprised of more than three components. The HSV color space is comprised of the following elements:

  • Red: falls between 0 and 60 degrees
  • Yellow: falls between 61 and 120 degrees
  • Green: falls between 121 and 180 degrees
  • Cyan: falls between 181 and 240 degrees
  • Blue: falls between 241 and 300 degrees
  • Magenta: falls between 301 and 360 degrees

Although HSV isn’t as commonly known as the RGB standard, many graphics professionals choose to use this color space when working in high-end graphics editing software suites.

Making Sense of It All

Regardless of the color space you use for your projects or displays, be it CIELAB, RGB, or HSV; you’ll always want to consider the Delta E levels of your equipment. If you choose devices with a high Delta E level, then you won’t be able to see image colors in the way that they were intended to be seen.

Since choosing a projector or monitor with a Delta E of less than two is important, you need to ensure that you select a high-quality display like the ViewSonic ColorPro. While these higher-end devices occasionally cost more than devices with low Delta E levels, you’ll find higher satisfaction by purchasing an advanced solution.