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About Relative Luminance Calculator
The WCAG Relative Luminance ($Y = 0.2126 R + 0.7152 G + 0.0722 B$) Calculator linearizes sRGB color channels, performs gamma correction ($sRGB \to Linear$), and computes photometric luminance values ($0.0$ to $1.0$).
How to Use Relative Luminance Calculator
Step 1
Enter a Hex, RGB, or HSL color value.
Step 2
Review computed linear RGB color components and final Relative Luminance ($Y$).
Step 3
Inspect intermediate mathematical formula breakdown.
Step 4
Click "Copy Luminance Value".
Practical Use Cases for Relative Luminance Calculator
Custom Accessibility Algorithm Development & Research
Compute precise physical relative luminance coefficients ($Y$) for custom color grading pipelines and accessibility testing libraries.
sRGB Linearization & Gamma De-companding Verification
Verify step-by-step sRGB gamma decoding ($V_{linear} = (V_{srgb} / 12.92)$ or $((V_{srgb}+0.055)/1.055)^{2.4}$) for accurate color science calculations.
Input & Output Examples
Calculating Luminance of CSS Dodger Blue (`#1E90FF`)
Hex: `#1E90FF`, sRGB: `R:30, G:144, B:255`
Linear RGB: `R:0.0121, G:0.2747, B:1.0000` | Relative Luminance ($Y$): `0.2741` | Perceived Brightness: `Medium-Bright`
Key Features & Performance
- ✓WCAG 2.1 Gamma Expansion: implements exact piecewise linearization formulas specified by IEC 61966-2-1.
- ✓Step-by-Step Mathematical Trace: shows intermediate linear R, G, B channels and luminance dot-product calculations.
- ✓Perceived Brightness Indicators: computes HSP and Rec. 709 luminance metrics alongside WCAG $Y$.
- ✓100% Client-Side color science engine.
- ✓1-Click Copy luminance values.
Key Terminology & Definitions
Relative Luminance ($Y$)
The relative brightness of any point in a colorspace, normalized to 0 for darkest black and 1 for lightest white, defined by ITU-R BT.709 coefficients ($Y = 0.2126 R_L + 0.7152 G_L + 0.0722 B_L$).
Gamma De-companding (Linearization)
The process of converting non-linear sRGB values encoded for display monitors into linear photometric values proportional to physical light intensity.