How does alpha affect the XYZ output?

Unlike LAB, this tool composites the RGBA color against a white background before converting. A fully transparent color (alpha=0) becomes pure white in XYZ; a fully opaque color (alpha=255) is converted as-is. This matches how colors actually appear on a white page or screen.

What illuminant does this tool use?

This tool uses the CIE D65 standard illuminant (6500 K daylight). The sRGB-to-XYZ matrix used is the standard one: X = 0.4124564·R + 0.3575761·G + 0.1804375·B; Y = 0.2126729·R + 0.7151522·G + 0.0721750·B; Z = 0.0193339·R + 0.1191920·G + 0.9503041·B.

What XYZ values should pure white produce?

rgba(255, 255, 255, 255) produces approximately X=0.9505, Y=1.0000, Z=1.0890, which is the D65 reference white point. Pure black (0, 0, 0, 255) produces X=Y=Z=0.

What is the expected XYZ for pure red?

rgba(255, 0, 0, 255) converts to approximately X=0.4125, Y=0.2126, Z=0.0193. You can verify this by entering R=255, G=0, B=0, A=255 in the tool.

Why are XYZ values between 0 and 1?

XYZ values are scaled so that the D65 reference white (pure white in sRGB) maps to approximately X=0.9505, Y=1.0000, Z=1.0890. Most colors produce XYZ values in the 0–1 range, though X and Z can slightly exceed 1 for saturated colors.

Does this tool send data to a server?

No. All conversion math runs entirely in your browser using JavaScript. No data is transmitted to any server.

RGBA to XYZ Converter

Name: RGBA to XYZ Converter
Availability: InStock
Author: Nham Vu

Enter RGBA values (0–255) and instantly get CIE XYZ tristimulus values with alpha composited against white and a live color swatch.

RGBA Input

Red (R) 255

Green (G) 0

Blue (B) 0

Alpha (A) 255

rgba(255, 0, 0, 255)

CIE XYZ Output

Y (Luminance)

Alpha: 255 / 255 (100.0%) — composited against white before XYZ conversion

Conversion Pipeline

1 Composite against white (alpha blend): Re=255, Ge=0, Be=0
2 sRGB gamma decode (linearize): Rl=1.0000, Gl=0.0000, Bl=0.0000
3 Linear RGB → XYZ (D65 matrix): X=0.4125, Y=0.2126, Z=0.0193

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Summary

Enter RGBA values (0–255) and instantly get CIE XYZ tristimulus values with alpha composited against white and a live color swatch.

How it works

Enter R, G, B values (0–255) and Alpha (0–255) in the input fields or drag the sliders.
The RGBA color is composited against white: R_eff = alpha*R/255 + (1-alpha)*255, and similarly for G and B.
Each effective RGB channel is linearized by reversing the sRGB gamma curve (IEC 61966-2-1).
The three linear-light values are multiplied by the standard sRGB-to-XYZ D65 matrix to produce X, Y, Z.
Results are displayed as raw XYZ values (typically 0–1 range) plus a formatted color() CSS string.
The color swatch previews the original RGBA color at the specified alpha level.

Use cases

Convert screen or CSS RGBA colors to CIE XYZ for color science work.
Feed XYZ values into further conversions such as CIELAB or CIELUV.
Verify sRGB-to-XYZ matrix implementations in color management pipelines.
Inspect how alpha compositing against white affects the resulting XYZ values.
Generate XYZ inputs for ICC profile calculations and colorimetric analysis.
Cross-reference RGBA colors between display space and device-independent XYZ.
Validate RGBA → XYZ math when implementing color science algorithms.
Build color palettes by comparing Y (luminance) values across RGBA swatches.

Frequently Asked Questions

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Last updated: 2026-05-28 · Reviewed by Nham Vu