About

The Munsell Color System, developed by Albert H. Munsell in 1905, defines color through three independent dimensions: Hue (H), Value (V), and Chroma (C). Unlike device-dependent RGB, Munsell notation is perceptually uniform and remains the standard for soil classification (USDA/FAO), archaeology, dentistry, and forensic science. Converting Munsell to digital RGB is non-trivial because the Munsell space is irregular. There is no closed-form equation. Accurate conversion requires the Munsell Renotation Data published by the Optical Society of America, which maps each chip to CIE x, y, Y coordinates under Illuminant C, then adapted to D65 for sRGB output.

Errors in Munsell-to-RGB conversion propagate into material specifications, paint matching, and scientific records. A naive linear mapping or simplified formula will produce visibly wrong colors, especially at high chroma. This tool uses real renotation data with trilinear interpolation for intermediate chips and applies the full CIE XYZ to sRGB pipeline with proper gamma companding. Chips that fall outside the sRGB gamut are clamped and flagged. Approximation accuracy is limited to the density of the renotation dataset and the sRGB gamut boundary.

Formulas

Conversion proceeds in three stages. First, Munsell notation is mapped to CIE x, y, Y coordinates via the Munsell Renotation Data. Second, CIE xyY is converted to CIE XYZ. Third, XYZ is transformed to linear sRGB and gamma-companded.

X = x ⋅ Yy

Z = (1 − x − y) ⋅ Yy

The XYZ to linear sRGB matrix (D65 reference white):

R_lin = 3.2406X − 1.5372Y − 0.4986Z

G_lin = −0.9689X + 1.8758Y + 0.0415Z

B_lin = 0.0557X − 0.2040Y + 1.0570Z

Gamma companding (IEC 61966-2-1):

C_sRGB =

{

12.92 ⋅ C_lin if C_lin ≤ 0.00313081.055 ⋅ C_lin^12.4 − 0.055 otherwise

Where C_lin is each of R_lin, G_lin, B_lin. The final 8-bit value is round(C_sRGB × 255). Neutral colors (N) have chroma 0 and map directly: R = G = B from Value alone using the Y luminance factor Y = V ⋅ (V − 0.1636) (Munsell Value function approximation).

Reference Data

Munsell Hue Code	Hue Name	Hue Angle (°)	Complementary Hue	Typical Max Chroma (V=5)
5R	Red	0	5BG	14
5YR	Yellow-Red	36	5PB	14
5Y	Yellow	72	5P	12
5GY	Green-Yellow	108	5RP	12
5G	Green	144	5R	10
5BG	Blue-Green	180	5R	8
5B	Blue	216	5YR	8
5PB	Purple-Blue	252	5YR	12
5P	Purple	288	5Y	12
5RP	Red-Purple	324	5GY	12
N	Neutral (Achromatic)	-	N	0
10R	Red (toward YR)	18	10BG	14
2.5YR	Yellow-Red (low)	27	2.5PB	12
7.5YR	Yellow-Red (high)	45	7.5PB	14
10YR	Yellow-Red (toward Y)	54	10PB	10
2.5Y	Yellow (low)	63	2.5P	10
7.5GY	Green-Yellow (high)	117	7.5RP	10
2.5G	Green (low)	135	2.5R	10
7.5B	Blue (high)	225	7.5YR	8
2.5PB	Purple-Blue (low)	243	2.5YR	10

Frequently Asked Questions

The Munsell color space is larger than sRGB. High-chroma chips (e.g., 5R 4/14) have CIE coordinates that, when transformed through the XYZ→sRGB matrix, produce negative or >1.0 channel values. These are clamped to [0, 255], which shifts the displayed color from the true Munsell specification. The tool flags these chips so you know the digital representation is approximate. For accurate reproduction, use a wider gamut display (Adobe RGB or DCI-P3).

The original Munsell Renotation Data was measured under CIE Illuminant C (6774 K, simulated daylight without UV). Modern sRGB uses D65 (6504 K). This tool applies a chromatic adaptation transform (Bradford matrix) from Illuminant C to D65 before the XYZ→sRGB step. Without this correction, blues and purples shift noticeably. The adaptation adds approximately 1-3 ΔE*ab units of error depending on the chip.

The renotation dataset provides chips at standard steps: Value integers 1-9, Chroma in steps of 2, and Hue at 2.5-unit intervals. For intermediate values (e.g., 3.7R 5.5/7), the tool performs trilinear interpolation across the three Munsell dimensions. Accuracy degrades near gamut boundaries and at very low Value (<2) or very high Chroma where the chip spacing is sparse. Typical interpolation error is under 2 ΔE*ab for mid-range colors.

Yes. Neutral colors use the notation N followed by Value (e.g., N 5/). Chroma is implicitly 0. The tool converts these using the Munsell Value function to derive luminance Y, then maps directly to equal R=G=B. N 0/ is absolute black (0, 0, 0) and N 10/ is reference white (255, 255, 255). Intermediate steps are non-linear due to the perceptual spacing of the Munsell Value scale.

HSL/HSV are mathematical transformations of the RGB cube with no perceptual uniformity. Munsell is an empirically measured, perceptually uniform system. There is no algebraic function mapping Munsell H/V/C to RGB. The only accurate path is through the measured CIE xyY data from the 1943 renotation study (updated by the RIT Munsell Color Science Laboratory). Any shortcut formula produces visible errors, particularly in the yellow-green and purple-blue regions where the Munsell hue circle deviates most from uniform angular spacing.

The tool accepts standard Munsell notation: HuePrefix Value/Chroma (e.g., 5R 4/10, 2.5GY 7/6, 10PB 3/12). For neutrals, use N Value/ (e.g., N 5/). Hue prefixes range from 2.5 to 10 in steps of 2.5 for each of the 10 hue families (R, YR, Y, GY, G, BG, B, PB, P, RP). Value ranges from 0 to 10. Chroma ranges from 0 to the maximum available for that hue/value combination. The parser is case-insensitive.