Color Comparison Tool: Calculate Delta E (ΔE)

What is Delta E (ΔE)?

Delta E (ΔE) is a metric used in colorimetry to quantify the difference between two colors. It was developed by the International Commission on Illumination (CIE) to provide a standardized way of measuring color differences that correlate with human perception.

Formula

The basic formula for Delta E (CIE76) is:

\[ \Delta E = \sqrt{(\Delta L^*)^2 + (\Delta a^*)^2 + (\Delta b^*)^2} \]

Where:

• \( \Delta E \) is the Delta E value
• \( \Delta L^* \) is the difference in lightness
• \( \Delta a^* \) is the difference in the red/green coordinate
• \( \Delta b^* \) is the difference in the yellow/blue coordinate

Calculation Steps

Let's calculate the Delta E between two colors:

1. Convert RGB values to L*a*b* color space for both colors
2. Calculate the differences: \( \Delta L^*, \Delta a^*, \Delta b^* \)
3. Apply the Delta E formula: \[ \Delta E = \sqrt{(\Delta L^*)^2 + (\Delta a^*)^2 + (\Delta b^*)^2} \]
4. Example calculation:
   • Color 1 (L*a*b*): (50, 2.6772, -79.7751)
   • Color 2 (L*a*b*): (50, 0, -82.7485)
   • \( \Delta L^* = 50 - 50 = 0 \)
   • \( \Delta a^* = 2.6772 - 0 = 2.6772 \)
   • \( \Delta b^* = -79.7751 - (-82.7485) = 2.9734 \)
   • \( \Delta E = \sqrt{0^2 + 2.6772^2 + 2.9734^2} \approx 4.001 \)

Example and Visual Representation

Let's visualize the Delta E concept:

This diagram illustrates:

• The L*a*b* color space (represented by the circle)
• Two different colors (red and yellow points)
• The Delta E as the distance between these two colors

Understanding Delta E values:

• 0-1: Not perceptible by human eyes
• 1-2: Perceptible through close observation
• 2-10: Perceptible at a glance
• 11-49: Colors are more similar than opposite
• 100: Colors are exact opposites