Delta E Calculator (ΔE*ab)
Calculate the Delta E (CIE76) color difference between two colors defined in the L*a*b* color space.
Enter L*a*b* Values
Color 1 (Reference)
Color 2 (Sample)
What is Delta E (ΔE)?
Delta E (often written as ΔE, dE, or dE*) is a metric used to quantify the difference between two colors. It represents the “distance” between two colors in the CIELAB (L*a*b*) color space, which was designed to be more perceptually uniform than other color spaces. In essence, a higher Delta E value means a greater difference in color as perceived by the human eye, while a lower Delta E means the colors are more similar.
The concept is crucial in fields where color accuracy is vital, such as printing, manufacturing, design, and digital imaging. It allows professionals to set objective tolerances for color matching and quality control. For example, if a brand has a specific logo color, they can use Delta E to ensure that the color is reproduced consistently across different materials and printing processes. To calculate Delta E, you need the L*a*b* values of the two colors you want to compare.
Who Should Use a Delta E Calculator?
- Graphic Designers & Printers: To ensure color consistency between digital designs and printed materials.
- Manufacturers (Paints, Plastics, Textiles): To maintain color quality and match standards across batches.
- Photographers & Videographers: For color correction and grading, ensuring colors look as intended.
- Color Scientists & Researchers: For studying color perception and developing color difference formulas.
- Quality Control Professionals: To set and check color tolerances in various industries.
Common Misconceptions About Delta E
- A Delta E of 1.0 is always the limit of perception: While often cited, the just noticeable difference (JND) can vary depending on the color, viewing conditions, and observer.
- All Delta E formulas are the same: There are several Delta E formulas (CIE76, CIE94, CIEDE2000) that calculate color difference differently, with newer formulas attempting to better model human perception, especially for certain color regions. Our calculator uses the original and simplest, CIE76.
- Delta E is the only factor in color matching: Factors like gloss, texture, and lighting conditions also significantly affect perceived color match.
Delta E Formula (CIE76) and Mathematical Explanation
The most common and simplest formula for Delta E is the one defined by the International Commission on Illumination (CIE) in 1976, often referred to as ΔE*ab or CIE76. It calculates the Euclidean distance between two points in the 3D L*a*b* space.
If you have two colors in L*a*b* space, Color 1 (L*1, a*1, b*1) and Color 2 (L*2, a*2, b*2), the Delta E (CIE76) is calculated as:
ΔE*ab = √((L*2 – L*1)2 + (a*2 – a*1)2 + (b*2 – b*1)2)
Where:
- ΔL* = L*2 – L*1 (Difference in lightness)
- Δa* = a*2 – a*1 (Difference in red/green)
- Δb* = b*2 – b*1 (Difference in yellow/blue)
So, the formula can also be written as: ΔE*ab = √(ΔL*2 + Δa*2 + Δb*2)
Variables Table
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| L* | Lightness | None | 0 (black) to 100 (white) |
| a* | Green-Red axis | None | -128 (green) to +127 (red) approx. |
| b* | Blue-Yellow axis | None | -128 (blue) to +127 (yellow) approx. |
| ΔL* | Difference in Lightness | None | -100 to 100 |
| Δa* | Difference in Green-Red | None | ~-255 to ~255 |
| Δb* | Difference in Blue-Yellow | None | ~-255 to ~255 |
| ΔE*ab | Total Color Difference (CIE76) | None | 0 (no difference) to ~100+ |
While CIE76 is straightforward, newer formulas like CIE94 and CIEDE2000 have been developed to address some of the perceptual non-uniformities of the L*a*b* space, providing results that may better correlate with human perception of color differences, especially for saturated colors or near neutrals.
Practical Examples (Real-World Use Cases)
Example 1: Checking Print Consistency
A company’s brand color is a specific blue, with L*a*b* values (50, -5, -30). A print run produces a color measured as (51, -6, -28).
- Color 1 (Reference): L*1=50, a*1=-5, b*1=-30
- Color 2 (Sample): L*2=51, a*2=-6, b*2=-28
- ΔL* = 51 – 50 = 1
- Δa* = -6 – (-5) = -1
- Δb* = -28 – (-30) = 2
- ΔE*ab = √(12 + (-1)2 + 22) = √(1 + 1 + 4) = √6 ≈ 2.45
A Delta E of 2.45 is generally noticeable, but might be acceptable depending on the application. The difference is mainly in lightness (ΔL*) and the blue-yellow axis (Δb*).
Example 2: Paint Matching
A car panel is being repainted. The original paint is measured at (85, 2, 5), and the new paint is (84.5, 2.2, 5.5).
- Color 1 (Original): L*1=85, a*1=2, b*1=5
- Color 2 (New): L*2=84.5, a*2=2.2, b*2=5.5
- ΔL* = 84.5 – 85 = -0.5
- Δa* = 2.2 – 2 = 0.2
- Δb* = 5.5 – 5 = 0.5
- ΔE*ab = √((-0.5)2 + (0.2)2 + (0.5)2) = √(0.25 + 0.04 + 0.25) = √0.54 ≈ 0.73
A Delta E of 0.73 is very small and likely imperceptible to most people, indicating a very good color match. For more on color difference, see our color difference guide.
How to Use This Delta E Calculator
- Enter L*a*b* Values for Color 1: Input the Lightness (L*1), a*1, and b*1 values for your reference color.
- Enter L*a*b* Values for Color 2: Input the L*2, a*2, and b*2 values for the sample or second color you want to compare.
- View Results: The calculator automatically updates and displays the Delta E (ΔE*ab) value, along with the differences in L* (ΔL*), a* (Δa*), and b* (Δb*). The chart also updates to show the L*, a*, and b* values for both colors.
- Interpret Delta E: Use the table below or general guidelines to understand the perceptual difference:
- ≤ 1.0: Not perceptible by human eye / trained eye might notice.
- 1-2: Perceptible through close observation.
- 2-10: Perceptible at a glance.
- 10-50: Colors are more similar than opposite.
- > 50: Colors are substantially different.
- Reset or Copy: Use the “Reset Values” button to go back to default inputs or “Copy Results” to copy the main Delta E and intermediate values.
Understanding the L*a*b* space is helpful. You can learn more about CIELAB explained here.
| Delta E Value | Perceptual Interpretation |
|---|---|
| 0 – 1 | Difference is generally not perceptible or only by a trained eye. |
| 1 – 2 | Difference is perceptible with close observation or to experienced eyes. |
| 2 – 3.5 | Difference is clearly perceptible to most people. |
| 3.5 – 5 | A clear difference in color is noticed. |
| > 5 | The two colors are perceived as very different. |
Key Factors That Affect Delta E Results
- L*, a*, b* Values: The core components. Small changes in these values directly impact the Delta E. The L*a*b* values are obtained using color measurement tools like spectrophotometers.
- Delta E Formula Used: CIE76 is simple, but CIE94 and CIEDE2000 weight differences in lightness, chroma, and hue differently, which can result in different Delta E values, especially for certain colors. CIEDE2000 is generally considered more accurate to human perception.
- Light Source and Viewing Conditions: The L*a*b* values themselves are measured under specific illuminants (like D65, D50). If the colors are viewed under different lighting, their perceived difference might change (metamerism).
- Observer Metamerism: Different people can perceive color slightly differently, even under the same lighting.
- Sample Texture and Gloss: The surface texture and gloss level can influence how color is perceived and measured, thus affecting the L*a*b* values and the calculated Delta E.
- Color Region: The human eye is more sensitive to changes in some colors (e.g., near-neutrals) than others (e.g., highly saturated colors). More advanced Delta E formulas try to account for this. Read more on understanding color tolerance.
Frequently Asked Questions (FAQ)
- What is a “good” or “acceptable” Delta E value?
- It depends entirely on the application. For high-end printing or automotive finishes, a Delta E below 1 or 2 might be required. For other applications, a Delta E of 3-5 might be acceptable. It’s about setting a color matching tolerance.
- Why use L*a*b* color space for Delta E?
- CIELAB was designed to be more perceptually uniform, meaning that the geometric distance between two colors in L*a*b* space is intended to correlate more closely with the perceived color difference than in spaces like RGB or CMYK.
- Can I calculate Delta E from RGB or CMYK values?
- Not directly. You first need to convert RGB or CMYK values to L*a*b* values using a standard illuminant and observer, then you can calculate Delta E.
- What are the limitations of the CIE76 Delta E formula?
- CIE76 treats all color differences equally regardless of where they are in the color space. Human vision is more sensitive to changes in some areas (like neutrals or low chroma colors) than others. CIE94 and CIEDE2000 attempt to correct for this.
- What is CIEDE2000?
- CIEDE2000 (ΔE*00) is a more complex color difference formula published in 2000. It includes weighting functions for lightness, chroma, and hue differences, and an interactive term between chroma and hue differences, generally providing better agreement with human perception.
- How are L*a*b* values measured?
- L*a*b* values are typically measured using color measurement instruments like spectrophotometers or colorimeters. These devices measure the light reflected or transmitted by an object under controlled lighting conditions. Many involve using spectrophotometers.
- Does Delta E account for gloss or texture?
- No, Delta E only measures the color difference based on L*a*b* values. Gloss and texture can significantly affect the *perceived* match, even if the Delta E is low.
- Is a Delta E of 0 possible?
- Yes, if the L*a*b* values of the two colors are identical, the Delta E will be 0, indicating a perfect match within the L*a*b* space.
Related Tools and Internal Resources
- Color Difference Guide: An in-depth look at understanding and interpreting color differences.
- CIELAB Explained: Learn more about the L*a*b* color space.
- Color Measurement Tools: Overview of tools used to measure color.
- Understanding Color Tolerance: How to set and use color tolerances in industry.
- Achieving Color Matching: Tips and techniques for effective color matching.
- Using Spectrophotometers: A guide to using these essential color measurement devices.