Base Color
HEX input updates all panels in real time.
Working Space
Select the primary working color space for analysis.
Observer Whitepoint
Reference whitepoint for XYZ computation.
Gamut Overlays
Color Analysis
Actions
Export & Share
JSON exports full color space data. Share URL encodes colour and working space.
Batch Analysis

Enter one HEX per line (max 50). Checks gamut membership across all spaces.

Click Run Batch to analyse colours.
Color Space Standards
sRGB / Rec.709

IEC 61966-2-1:1999 — Standard default colour space for the Internet. Defines sRGB primaries (0.64, 0.33), (0.30, 0.60), (0.15, 0.06) under D65 illuminant with a piecewise gamma (linear segment + 2.4 power). Adopted by virtually all consumer displays, web browsers, and image formats (JPEG, PNG, CSS).

ITU-R BT.709-6 (2015) — Defines the same primaries and whitepoint for HDTV production. The OETF differs slightly from sRGB (uses 0.45 power law) but the colorimetric gamut is identical.

Display-P3

ISO 22028-3:2012 (DCI-P3 origin) — Wide-gamut space derived from DCI-P3 cinema standard. Apple adapted it as Display-P3 with D65 whitepoint and sRGB transfer function. Covers ~25% more CIE visible area than sRGB. Used by Apple displays, modern OLED panels, and CSS color(display-p3 ...) notation.

Rec.2020

ITU-R BT.2020-2 (2015) — Ultra-wide gamut for UHDTV and HDR content. Primaries are laser-pure single-wavelength values: R 630 nm, G 532 nm, B 467 nm. Covers ~75.8% of the CIE 1931 visible gamut. Transfer function uses a 12-bit piecewise curve (α=1.0993, β=0.0181).

ACEScg (AP1)

ACES 1.0.3 — S-2014-004 — Academy Color Encoding System computer graphics working space. AP1 primaries are fully realizable (within the spectral locus) while covering a wide gamut. Uses D60 whitepoint and scene-linear transfer function. Standard for VFX compositing and CGI rendering.

ProPhoto RGB (ROMM RGB)

ISO 22028-2:2013 — Extremely wide gamut space created by Kodak for photographic workflows. Covers ~91% of visible colors. Uses D50 whitepoint and 1.8 gamma (linear segment below 1/512). Widely used in professional photo editing with ICC v4 profiles. Some primaries are imaginary (outside spectral locus).

Chromatic Adaptation (Bradford)

Bradford CAT (Lam 1985, refined Hunt 1994) — Chromatic Adaptation Transform using a cone-response-like matrix tuned to human adaptation. Preferred CAT in ICC v4 profiles for D50↔D65 conversion. Outperforms von Kries and XYZ scaling in predicting corresponding colors.

CIE 16:2004 — Colorimetry — Defines standard procedures for chromatic adaptation. Recommends Bradford-type transforms for practical use in imaging and color management.

ICC Profiles

ICC.1:2022 (v4.4) — International Color Consortium profile specification. Defines structure, required tags (PCS = CIEXYZ or CIELAB under D50), rendering intents, and profile connection space. All ICC v4 profiles use D50 PCS whitepoint, requiring Bradford CAT from native illuminant.

CIE Chromaticity

CIE 15:2004 — Colorimetry — Official computation of CIE 1931 (x, y) and CIE 1976 (u′, v′) chromaticity coordinates. u′ = 4X / (X + 15Y + 3Z), v′ = 9Y / (X + 15Y + 3Z). The uniform u′v′ space provides better perceptual spacing than xy.

Smith & Guild, 1931 — Original CIE 1931 2° Standard Observer color matching functions. Foundation for all colorimetric computation.

Color Difference

Sharma, Wu & Dalal, 2005 — “The CIEDE2000 Color-Difference Formula: Implementation Notes.” Defines the complete ΔE₀₀ formula with lightness, chroma, hue weighting plus rotation term for the blue region. Standard metric for critical color evaluation.

Formulas & Mathematics
sRGB Transfer Function
Encode (linear → sRGB):
C_sRGB = 12.92 × C_lin   if C_lin ≤ 0.0031308
C_sRGB = 1.055 × C_lin^(1/2.4) − 0.055   otherwise

Decode (sRGB → linear):
C_lin = C_sRGB / 12.92   if C_sRGB ≤ 0.04045
C_lin = ((C_sRGB + 0.055) / 1.055)^2.4   otherwise
Rec.2020 Transfer Function
OETF inverse (12-bit precision):
α = 1.09929682680944, β = 0.018053968510807
E′ = 4.5 × E   if E < β
E′ = α × E^0.45 − (α − 1)   otherwise
ProPhoto RGB Transfer Function
E′ = 16 × E   if E ≤ 1/512
E′ = E^(1/1.8)   otherwise
RGB → XYZ Matrix Derivation
Given primaries (xR,yR), (xG,yG), (xB,yB) and whitepoint (xW,yW):

1. XYZ of each primary: X = x/y, Y = 1, Z = (1-x-y)/y
2. Form matrix M = [XR XG XB; YR YG YB; ZR ZG ZB]
3. Solve M-inv * [Xw Yw Zw]T = [SR SG SB]T
4. Final M_RGB-XYZ = [SR*XR SG*XG SB*XB; SR*YR SG*YG SB*YB; SR*ZR SG*ZG SB*ZB]
Bradford CAT
M_adapt = M_Brad-inv * diag(pD/pS, gD/gS, bD/bS) * M_Brad

where [p, g, b]T = M_Brad * [X, Y, Z]T of each illuminant.

M_Bradford (XYZ to sharpened LMS):
| 0.8951 0.2664 -0.1614 |
|-0.7502 1.7135 0.0367 |
| 0.0389 -0.0685 1.0296 |
CIE 1931 xy Chromaticity
x = X / (X + Y + Z)
y = Y / (X + Y + Z)
CIE 1976 u'v' Chromaticity
u' = 4X / (X + 15Y + 3Z)
v' = 9Y / (X + 15Y + 3Z)
CIELAB from XYZ
f(t) = t^(1/3) if t > epsilon, else (kappa*t + 16)/116
epsilon = 216/24389, kappa = 24389/27

L* = 116*f(Y/Yn) - 16
a* = 500*[f(X/Xn) - f(Y/Yn)]
b* = 200*[f(Y/Yn) - f(Z/Zn)]
CIEDE2000 (dE00)
dE00 = sqrt[(dL'/SL)^2 + (dC'/SC)^2 + (dH'/SH)^2 + RT*(dC'/SC)*(dH'/SH)]

Weighting functions:
SL = 1 + 0.015*(Lbar'-50)^2 / sqrt(20+(Lbar'-50)^2)
SC = 1 + 0.045*Cbar'
SH = 1 + 0.015*Cbar'*T

RT corrects hue/chroma interaction in the blue region (hbar' approx 275 deg).
Gamut Area (xy Triangle)
A = 1/2 |xR(yG-yB) + xG(yB-yR) + xB(yR-yG)|

Coverage = A / A_visible * 100%
A_visible approx 0.1955 (CIE 1931 spectral locus area)
References & Citations

Color Space Standards

[1] IEC 61966-2-1:1999 — Default RGB colour space — sRGB.

[2] ITU-R BT.709-6 (2015) — Parameter values for the HDTV standards.

[3] ISO 22028-3:2012 — Extended colour encodings for digital image storage.

[4] ITU-R BT.2020-2 (2015) — Parameter values for ultra-high definition television.

[5] S-2014-004 (ACEScg) — A Working Space for CGI Render and Compositing, ACES 1.0.3.

[6] ISO 22028-2:2013 (ROMM RGB) — Reference output medium metric RGB colour space.

Chromatic Adaptation

[7] Lam, K.M. (1985) — Metamerism and Colour Constancy. PhD Thesis, University of Bradford.

[8] Hunt, R.W.G. (1994) — An improved predictor of colourfulness in a model of colour vision. Color Research & Application, 19(1), 23-26.

[9] CIE 16:2004 — Colorimetry. Chromatic adaptation procedures and recommendations.

[10] ICC.1:2022 (v4.4) — International Color Consortium Profile Specification.

CIE Colorimetry

[11] CIE 15:2004 — Colorimetry (3rd Edition). Standard observer, illuminants, chromaticity.

[12] Smith, T. & Guild, J. (1931) — The C.I.E. colorimetric standards and their use. Transactions of the Optical Society, 33(3), 73-134.

[13] Wright, W.D. (1928) — A re-determination of the trichromatic coefficients of the spectral colours. Transactions of the Optical Society, 30(4), 141-164.

Color Difference

[14] Sharma, G., Wu, W. & Dalal, E.N. (2005) — The CIEDE2000 Color-Difference Formula. Color Research & Application, 30(1), 21-30.

[15] CIE 142:2001 — Improvement to industrial colour-difference evaluation.

General Resources

[16] Lindbloom, B. — brucelindbloom.com — Comprehensive colour mathematics and matrices.

[17] Poynton, C.A. (2012) — Digital Video and HD: Algorithms and Interfaces (2nd ed.).

[18] Fairchild, M.D. (2013) — Color Appearance Models (3rd ed.). Wiley.

About this tool

This tool implements 5 color spaces (sRGB, Display-P3, Rec.2020, ACEScg, ProPhoto RGB) with CIE 1931 xy and 1976 u′v′ chromaticity visualization, Bradford chromatic adaptation, CIEDE2000 cross-space metrics, gamut coverage analysis, and multi-space matrix inspection — entirely client-side (zero network). Not a substitute for calibrated measurement or ICC profile software.

Research & Visualization
CIE 1931 xy Chromaticity
CIE 1976 u′v′ Chromaticity
Gamut Coverage (% of CIE 1931 Visible)
Research backend: sRGB · Display-P3 · Rec.2020 · ACEScg · ProPhoto RGB · CIE 1931 xy · CIE 1976 u′v′ · Bradford CAT · CIEDE2000 · Gamut coverage · Matrix diagnostics · Batch analysis. All computation on-device.