What is Delta E?

Delta E (also commonly written as Δ E and E*) is a measure of color difference. It represents the "color difference" or "distance" between two color samples and can quantify the similarity of two colors. Delta E value The lower the value, the smaller the color difference, and the closer the displayed color is to the original color. This concept was first proposed by the International Commission on Illumination (CIE) in the 1970s to solve the problem of color deviation in different devices, printing media or lighting conditions.

Through Delta E, people can accurately judge the degree of match between a certain color and the target color, providing a scientific basis for color management, calibration and consistency control. Delta E is widely used in fields such as electronic display, printing and manufacturing that have strict requirements on color accuracy. Delta E expresses color difference through numerical values, allowing professionals to achieve color consistency between digital devices and physical objects, thereby optimizing the final color presentation effect.

Comparison and application scenarios of different versions of color difference formula

Delta E has evolved into different calculation standards, each with its own specific application scenarios and areas of application:

1. Basic color difference formula

Delta E 76 (CIE76): Also written as Δ E*ab, this formula in 1976 is the earliest Delta E calculation standard. It is based on Euclidean distance and CIELab color space . The calculation is relatively simple, but CIE76 lacks accuracy for some subtle color differences. This standard is still used in some simple color matching scenarios.

Delta E (Hunter): Also written as Δ E, it is an early color difference calculation method based on the Hunter Lab color space, originally proposed by Richard S. Hunter. It is relatively simple and suitable for early color difference calculations, but it is not as accurate as the CIELab color space method.

2. Moderately accurate color difference formula for industrial applications

Delta E 94 (CIE94): Also written as Δ E *94 , it improves the simulation of human color perception, taking into account the brightness and saturation of the color, and can more accurately reflect the human eye's perception of color difference. This standard is suitable for printing and basic manufacturing scenarios.

· ΔE*cmc(2:1) and ΔE*cmc(1:1): are color difference calculation methods proposed by CMC (Color Measurement Committee) and designed for the textile industry. This formula can adjust the weights of brightness and chromaticity. (2:1) has higher requirements on brightness, while (1:1) has equal weights on brightness and chromaticity. It is widely used in textile, plastic and other industries.

3. Highly accurate modern standard color difference formula

Delta E 2000 (CIEDE2000): Also written as ΔE*00 , the most advanced Delta E calculation standard, which comprehensively considers hue, brightness and saturation of color, as well as the difference in perception brought by different areas of color, is closer to human eye perception. Delta E 2000 is suitable for fields that require high-precision color difference measurement, such as advanced display device calibration , professional image production , coatings industry and cosmetics .

DIN ΔE99: A color difference formula proposed by the German Institute for Standardization (DIN) in 1999. It is based on the improvement of CIELab and meets the needs of German industry. This formula has high color difference uniformity and is widely used in industrial applications in Europe, suitable for printing and coatings.

4. Special Application Color Difference Formula

· ΔE*uv : Color difference calculation based on CIELuv color space, mainly used to evaluate the color consistency of displays, light sources, etc. It is suitable for CIELuv color space with high uniformity and can evaluate the color difference of light sources more accurately.

Each version of the Delta E standard provides different application options, allowing users to choose the most suitable standard according to their needs. Delta E 2000 is usually the first choice for high-demand scenarios, such as color calibration and high-precision printing. 3nh's color detection instruments such as spectrophotometers and colorimeters have built-in multiple color difference formulas to choose from.

How to interpret Delta E values

The significance of the commonly used ΔE value range

The Delta E value indicates the difference between two color samples. Understanding the change in Delta E values can help users determine the consistency of color and whether it is within the acceptable range:

ΔE ≤ 1: Color difference is barely perceptible to the naked eye, indicating highly accurate color matching, often used in demanding fields such as advanced displays, photography, and video editing.

1 < ΔE ≤ 2: The human eye can only detect color differences under careful comparison. This is professional-level color accuracy, suitable for printing and high-end electronic devices.

2 < ΔE ≤ 3: Slight color difference, visible only under strict comparison, usually meets general needs such as consumer electronics and graphic design.

3 < ΔE ≤ 5: Obvious color difference, which may affect the viewing experience. It is not recommended for industries with high requirements for color consistency (such as brand printing).

ΔE > 5: Significant color difference, easily noticeable to the naked eye. Not suitable for any occasions requiring color accuracy, only for scenes with high tolerance.

Tolerance standards for ΔE values in different industries

Different industries have different tolerance standards for Delta E, and the specific numerical requirements also vary according to the application scenario:

Consumer electronics (such as monitors and TVs): Consumer electronics products usually control Delta E below 3 to ensure that the color is close to reality, but allow a certain color difference. This range is usually sufficient for daily viewing and general use.

Printing and publishing: The printing and publishing industries have higher requirements for color consistency. Delta E is usually controlled within 2 to ensure that the color remains consistent between different batches, especially for brand spot color printing, which requires strict control.

Photography and filmmaking: In image production, Delta E is usually less than 1 to ensure that the captured colors are accurately presented on the screen or printed. High precision is especially required in color grading and film editing.

Textile and Manufacturing: Color consistency is critical in the manufacturing of textiles and coatings. The Delta E target value is generally controlled between 2 and 3 to ensure consistency between product batches and ensure compliance with customer brand or design requirements.

NBS color difference unit

The NBS color difference unit is derived from the color difference calculation formula established by Judd-Hunter. In 1939, the National Bureau of Standards of the United States adopted the color difference calculation formula and used it to calculate the color difference. When the absolute value is 1, it is called the "NBS color difference unit". New color difference formulas developed later often consciously adjust the unit to be close to the NBS unit, such as Hunter The units of color difference formulas such as Lab, CIE LAB, and CIE LUV are roughly the same as NBS units (not equal). Therefore, do not misunderstand that the color difference units calculated by other color difference formulas are all NBS. Although there is no direct formula conversion between NBS units and ΔE, NBS units can be used as a reference to describe the visual effect of ΔE values. For example, when the ΔE*ab or ΔE*00 value is below 0.5, it can usually be considered to be equivalent to the "minor color difference" of NBS, that is, it is almost imperceptible; and when the ΔE value is between 3-6, it can usually be regarded as a "large color difference" and visually obvious.

NBS Unit and Color Difference Sensation

Delta E calculation formula

1. ΔE*ab Basic formula

· L1, a1, b1 and L2, a2, b2 represent the CIELab color values of two colors.

· This formula is simple but lacks precision in cases with low saturation or extreme brightness.

2. ΔE*94 formula structure

3. Calculation method of ΔE*00

4. The formula structure of ΔE*cmc

5. Calculation of DIN ΔE99

DIN ΔE99 is a color difference formula proposed by the German Institute for Standardization. It improves ΔE*ab to obtain a more uniform color difference distribution. It is suitable for industrial applications in Europe, especially the printing and coating industries. The formula is relatively complex and is mainly adjusted by nonlinear item to improve accuracy.

The specific formula of DIN ΔE99 is relatively complex and is usually calculated in dedicated software. Its structure is similar to ΔE*00, but it is more focused on the industrial standardization requirements of Germany and Europe.

Delta E Application Areas : How to Choose the Right Delta E

The selection of the appropriate Delta E standard and target value depends on the specific application and use:

High-end monitor calibration

High-end monitors are calibrated with a colorimeter before leaving the factory to control Delta E within 1 to ensure the true reproduction of displayed colors. This strict calibration requirement applies to professional graphic designers, photographers, and video producers to ensure that the colors displayed on the screen are consistent with the colors of the real image.

Brand packaging printing

The color of brand packaging needs to be highly consistent, especially in spot colors (such as logo colors). Printing houses will use the standard of Delta E controlled within 2 to ensure that there is no obvious color difference between different batches of packaging and maintain the unity of the brand image.

Textile dyeing

In the textile industry, dyeing factories control the Delta E value between batches to be within 3 to keep the color of the fabric consistent and prevent the risk of product returns due to color difference. For some high-demand customers, Delta E may be required to be controlled within 2.

By selecting the appropriate Delta E value and standard, you can ensure the best color performance in different application scenarios.

How to measure Delta E
Measuring Delta E requires accurate color detection equipment and consistent measurement conditions and methods:

Main measurement tools: 3nh advanced colorimeter and spectrophotometer are used to measure color data.

Environmental control: Color difference measurements should be performed under standard lighting conditions to avoid natural light changes affecting the measurement results.

Measurement steps: First record the reference color sample data, then measure the color sample to be measured, and enter the result into the Delta E formula for calculation.

Through strict measurement procedures, the reliability of color difference values can be ensured, providing support for color management in different devices and environments.