In your search for a computer monitor for graphic design, you may be wondering, “What is Delta E?” In short, it is an index of how much the displayed color deviates from the original color. The lower the Delta E, the more accurate the color. So what level of Delta E is enough? This depends on your needs (and we provide a useful guide to Delta E values below).
In the consumer and business electronics industry, there is a lot of jargon that confuses buyers. We’ve already covered a few topics like lumens and resolution. However, one of the more abstract terms you are likely to encounter in this field is Delta E (usually written as ΔE or E*).
Delta E is an index that plays an important role in evaluating color accuracy. Creative professionals such as photographers, video editors, and graphic designers need to pay attention to this standard as it is an essential factor in choosing a dedicated monitor.
While creative professionals need to understand the meaning of Delta E; Given the complexity of the topic, it is easy to lose the meaning of this definition in translation. With that in mind, let’s take a closer look at Delta E and how to use it to make informed decisions when purchasing display equipment.
Table of Contents
What is Delta E?
Delta E is a standard measurement index created by the International Commission on Illumination (Commission Internationale de l’Eclairage) to determine the degree of deviation between two colors on a screen. When shopping for a projector or digital display, you’ll want to find a device with a Delta E rating as close to zero as possible.
Delta E level is the deviation between the displayed color and the standard base color of the input content. A lower Delta E index means the color is more accurate, and a higher Delta E index means greater deviation.
The “E” in Delta E is “Empfindung”, which means “feeling” in German. Delta is the Greek word for the gradual change of a variable. When put together, the term Delta E refers to a difference in feel.
Delta E is measured on a scale from 0 to 100, where 0 indicates low color deviation, and 100 indicates complete color deviation. As explained in Zachary Schuessler’s tutorial, the perception of this color standard is divided into the following value ranges:
<= 1.0: The human eye cannot perceive the difference
1-2: Can be felt if observed carefully
2-10: Feel it at a glance
11-49: Colors are more like contrasting colors
100: The color contrasts completely with the original color
Why is Delta E Important in Graphic Design?
Professionals need to understand the meaning of Delta E because, as explained above, this index is the basis of color accuracy. This index can be used alone to determine whether the screen displays colors accurately or not, instead of relying on subjective assessment.
Not just limited to aesthetics and display capabilities, when one owns a set of displays with a low Delta E level, one can perform complex tasks such as graphics and video editing on multiple displays without experiencing serious color distortion.
How to Calculate Delta E
Delta E (total color difference) is calculated based on the color values delta L*, delta a*, and delta b*, all of which represent a complete numerical description of the color in the rectangular coordinate system. The meaning of the above values is as follows:
dL* represents the brightness difference between the sample color and the standard color.
da* represents the difference in red or gray between the sample color and the standard color.
db* represents the difference in blue and yellow hues between the sample color and the standard color.
With the levels mentioned above, the higher the value, the greater the deviation in that aspect. Since Delta E revolves around three core factors, this metric is easier to calculate than you might think.
You just need to square the difference between each value L, a, and b, add them up, and take the square root of that sum.
This formula provides important information about the perceived deviation between two colors. The more precise formula is Delta E(94). The formula for Delta E(94) is much more complicated than the standard Delta E formula, so this article will not cover it.
Why should you choose a screen with Delta E ≦2?
When your work involves creative work, you will want to buy devices with a Delta E level of less than 2 because then the human eye will see the colors displayed on the screen as the original color.
In general, the best quality displays at a price are significantly more expensive than traditional devices with a Delta E rating of 1 or less. However, this index cannot go down to 0. Besides, high-end, high-quality devices have Delta E ≦2.
How to Measure Color
A common question in discussions about Delta E levels is how to accurately measure color. Although you can use scales and rulers to measure weight and size, brightness is more difficult to measure. Depending on the color space you use, there will be different formulas.
As for the actual equipment to measure brightness, you can buy a colorimeter. This instrument measures luminance using a set of XYZ filters, which are optical filters designed to simulate the optical properties of triplet (XYZ) values. Color triadic values are the basis of color language and are also considered the CIE color system.
What is CIELAB
CIELAB is the color space or “CIE L*a*b*” or simply “Lab Color Space”. This value was created by the National Commission on Illumination in 1976 to represent color in three values. Hunterlab has an overview article on this topic with the following main contents.
L* represents brightness, where 0 indicates pure black, 0% reflectivity or color transmission. A 50% index indicates a neutral gray value, while a 100 index indicates a pure white. This index indicates a reflectivity of 100% and perfect clarity.
a* represents the red and gray hues of the color. Positive values of a* are red and negative values are green. Level 0 is a neutral color.
b* represents the yellow and blue hues of the color. Positive values of b* are yellow and negative values are blue. 0 indicates a neutral level.
Since CIELAB is measured in three spatial dimensions, there are countless possibilities for color representation. The CIELAB model also adheres to eternal uniformity. This helps color standards estimate human vision more accurately. As a result, this color standard has a significant advantage over the less precise RGB and CMYK color standards.
CIELAB provides precision at a level requiring much larger amounts of data per pixel than RGB and CMYK standards. Because the standard color range is higher than that of most computer monitors, sometimes colors will not be accurate; however, advances in technology make these issues less of a concern.
The CIELAB model is device-agnostic, meaning that the definition of color is developed independently of how the color is created or displayed. The most common application of this color space is to convert graphic images for printing from RGB to CMYK.
Because the Lab space is purely mathematically defined, CIELAB is copyright and license-free. CIELAB is also completely in the public domain, meaning you can use and integrate this model into your projects at no cost.
Other Popular Color Spaces: RGB and HSV
Although it is one of the most popular standards in the industry, CIELAB is not the only large color space. The RGB and HSV color spaces are worth discussing in this article because they both play an important role in the quality of digital graphics.
The RGB color space, which stands for red-green-blue, is a complementary color model, meaning that many ratios of these lights can be used to create any color. This color model is created specifically for display purposes, like monitors and projectors.
Many display screens are made up of red, green, and blue light. When viewed from a distance, usually more than 60 cm, the colors combine. When examined at close range, the human eye can distinguish colors.
Although RGB is an effective color standard, computer graphics professionals find it difficult to use it to create complex color tones. Therefore, the HSV color space was born. This is essentially a more convenient version of the RGB color space.
HSV stands for hue, saturation, and value, and gives a more accurate level of color perception than other standards. The reason is because this color space includes more than three components. HSV color space includes the following elements:
Red: ranges from 0 to 60 degrees
Yellow: ranges from 61 – 120 degrees
Green: ranges from 121 – 180 degrees
Cyan: ranges from 181 – 240 degrees
Blue: ranges from 241 – 300 degrees
Magenta: ranges from 301 – 360 degrees
Although the HSV standard is not as popular as the RGB standard, many graphics professionals choose this color space when using high-end graphics editing software suites.
Summary
No matter what color space you use for your projection device or display, whether CIELAB, RGB, or HSV, you will always need to consider the device’s Delta E level. If you choose devices with high Delta E levels, the displayed image will not retain its original color.
Because of the importance of choosing a projector or screen with a Delta E of less than 2, you need to make sure to choose a high-quality screen like ViewSonic ColorPro. Although these high-end devices will sometimes cost more than low-Delta E devices, you will feel better about investing in an advanced solution.