Delta E Calculator (using LAB)

Calculate the perceptual color difference using the CIE76 formula.

Reference Color (Color 1)

Sample Color (Color 2)

Calculation Results

Delta E (CIE76)

ΔL*

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Δa*

—

Δb*

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What is a Delta E Calculator using LAB?

A delta E calculator using LAB is a tool used to quantify the difference between two colors. The term “Delta E” (also written as dE or ΔE) literally means “difference in sensation.” It’s a metric that represents the “distance” between two colors in the CIELAB (L*a*b*) color space. The CIELAB color space is a three-dimensional model designed to approximate human vision, where every perceptible color has a unique coordinate.

This calculator is essential for professionals in fields like printing, graphic design, manufacturing, and photography, where color accuracy is critical. By inputting the L*, a*, and b* values of a reference color and a sample color, the calculator computes a single number, the Delta E value, which indicates the magnitude of their visual difference.

The Delta E (CIE76) Formula and Explanation

The most common and straightforward formula for calculating color difference is the CIE76 formula. It calculates the Euclidean distance between two points in the 3D L*a*b* space. While more complex formulas like CIE94 and CIEDE2000 exist for better perceptual uniformity, CIE76 remains a widely used standard for basic color difference assessment.

The formula is:

ΔE*_ab = √[(L*₂ – L*₁)² + (a*₂ – a*₁)² + (b*₂ – b*₁)²]

Or, expressed using delta notation:

ΔE*_ab = √[(ΔL*)² + (Δa*)² + (Δb*)²]

Variable Explanations for the Delta E Formula

Variable	Meaning	Unit	Typical Range
L*	Lightness coordinate	Unitless	0 (Perfect Black) to 100 (Perfect White)
a*	Green-Red coordinate	Unitless	-128 (Green) to +127 (Red)
b*	Blue-Yellow coordinate	Unitless	-128 (Blue) to +127 (Yellow)
ΔL*, Δa*, Δb*	The difference for each respective coordinate (e.g., L*₂ – L*₁)	Unitless	Varies
ΔE*ab	The total color difference (Delta E)	Unitless	0 to 100+

Practical Examples

Example 1: Subtle Shade Difference

Imagine a printer needs to match a specific shade of corporate grey. The reference color has been measured, and now they are checking a new print sample.

• Reference Color (Color 1): L*=50, a*=0, b*=0 (a neutral grey)
• Sample Color (Color 2): L*=51, a*= -1, b*=1.5 (a slightly lighter, cooler grey)

Using the delta E calculator using lab, the calculation would be:

ΔL* = 51 – 50 = 1
Δa* = -1 – 0 = -1
Δb* = 1.5 – 0 = 1.5

ΔE*_ab = √[(1)² + (-1)² + (1.5)²] = √[1 + 1 + 2.25] = √4.25 ≈ 2.06

A Delta E of 2.06 is a small but perceptible difference, visible upon close inspection.

Example 2: Comparing Vibrant Colors

A designer is comparing two shades of red for a logo.

• Reference Red (Color 1): L*=45, a*=70, b*=55
• Sample Red (Color 2): L*=48, a*=65, b*=58

ΔL* = 48 – 45 = 3
Δa* = 65 – 70 = -5
Δb* = 58 – 55 = 3

ΔE*_ab = √[(3)² + (-5)² + (3)²] = √[9 + 25 + 9] = √43 ≈ 6.56

A Delta E of 6.56 is a clearly noticeable difference.

How to Use This Delta E Calculator

Follow these simple steps to measure color difference:

1. Enter Reference Values: In the ‘Reference Color (Color 1)’ section, input the L*, a*, and b* values of your standard or original color.
2. Enter Sample Values: In the ‘Sample Color (Color 2)’ section, input the L*, a*, and b* values of the color you want to compare.
3. Calculate: Click the “Calculate Delta E” button.
4. Interpret Results:
   • The main Delta E (CIE76) result shows the total color difference.
   • The intermediate ΔL*, Δa*, and Δb* values show you how the colors differ on each axis (e.g., if one is lighter, more red, or more yellow).
   • The bar chart provides a quick visual comparison of the individual L*, a*, and b* components.

Key Factors That Affect Delta E

1. Lighting Conditions: The perceived color of an object can change dramatically under different light sources (e.g., sunlight vs. fluorescent light). This phenomenon is called metamerism.
2. Observer Variation: Color perception is subjective and can vary from person to person due to age, eye health, and other biological factors.
3. Substrate and Texture: The material and texture of the surface being measured (e.g., glossy paper, fabric, plastic) can affect how light reflects and thus alter the measured LAB values.
4. Measurement Device: The accuracy and calibration of the spectrophotometer or colorimeter used to get the LAB values are critical. Inconsistent measurements will lead to meaningless Delta E values.
5. Formula Choice: As mentioned, CIE76 is the simplest formula. Newer formulas like CIE94 and CIEDE2000 are weighted to better match human perception, especially for saturated colors. A delta e calculator using lab might offer different formula options.
6. Viewing Angle: The angle at which an object is viewed can sometimes affect its perceived color, particularly with metallic or pearlescent finishes.

Frequently Asked Questions (FAQ)

1. What is a “good” Delta E value?

This depends heavily on the application. Generally, a Delta E of less than 1.0 is considered imperceptible to the human eye. A value between 1.0 and 2.0 is a very small difference, only noticeable on close inspection. Values between 2.0 and 10.0 represent increasingly noticeable differences.

2. What do the L*, a*, and b* values mean?

L* represents lightness (0-100). a* represents the green-to-red scale (negative is green, positive is red). b* represents the blue-to-yellow scale (negative is blue, positive is yellow).

3. Are the LAB values unitless?

Yes, the L*, a*, and b* coordinates, and the resulting Delta E value, are considered unitless. They are simply numerical representations within the defined CIELAB color space.

4. Why use a delta e calculator instead of just comparing RGB values?

The RGB color model is device-dependent and not perceptually uniform. This means a change of 10 in the Blue value does not look the same as a change of 10 in the Red value. The CIELAB space was specifically designed so that the geometric distance between two colors corresponds more closely to the perceived visual difference.

5. What is the difference between CIE76, CIE94, and CIEDE2000?

They are different versions of the Delta E formula. CIE76 is the original and simplest. CIE94 and CIEDE2000 are more complex formulas that were developed to correct for inconsistencies in the CIE76 formula, providing results that better align with human perception, especially in how we perceive differences in chroma (saturation).

6. Can a negative Delta E exist?

No. Because the formula squares the differences of the L*, a*, and b* components, the inputs to the square root are always non-negative. Therefore, the Delta E value is always zero or positive.

7. How do I get the LAB values for a color?

You need a measurement device called a spectrophotometer or a colorimeter. These instruments shine a controlled light source onto a surface and measure the reflected light to calculate the precise L*a*b* coordinates.

8. What does a Delta E of 0 mean?

A Delta E of 0 means the two colors are identical (L*₁, a*₁, b*₁ are the same as L*₂, a*₂, b*₂).

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