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Category Tests

Number of chips

Hue range

Select settings and press Start. Drag the color chips into the correct hue order from left to right.

Difficulty

Find the patch with a different saturation level. Click it.

Difficulty

Find the patch with a different brightness. Click it.

Gradient hue

How many bands do you see?

Render the gradient, then count how many distinct bands you perceive.

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About

Human color perception relies on three cone cell types (S, M, L) responding to wavelengths between 380nm and 700nm. A typical observer discriminates roughly 1 million distinct colors, but individual variance is substantial. Anomalous trichromacy affects approximately 8% of males and 0.5% of females. Misidentifying colors carries real consequences in fields like electrical wiring, medical diagnostics, aviation, and graphic design. This tool measures your ability to discriminate hue, saturation, and brightness across the visible spectrum using methods inspired by the Farnsworth-Munsell D-15 arrangement protocol. It does not replace clinical diagnosis but provides a quantitative approximation of your chromatic discrimination threshold, expressed as a total error score TES where lower values indicate finer perception.

The gradient banding test evaluates your display and eyes jointly. If you see hard bands in what should be a smooth gradient, either your monitor bit-depth is limited or your brightness discrimination in that hue region is reduced. Results are approximations under current ambient lighting and display calibration. For clinical accuracy, consult an optometrist with calibrated Munsell chips under D65 illuminant.

Formulas

The Total Error Score is computed by summing the absolute hue displacement of each chip from its correct position in the arrangement sequence:

TES = n∑i=1 |H_placed,i − H_correct,i|

Where H_placed,i is the hue angle of the chip at position i in the user's arrangement, and H_correct,i is the target hue at that position. Hue differences wrap at 360°:

ΔH = min(|a − b|, 360 − |a − b|)

Color difference in CIE Lab space uses the Euclidean metric (CIE76):

ΔE = √(L₁ − L₂)² + (a₁ − a₂)² + (b₁ − b₂)²

Where L is lightness, a is the green - red axis, and b is the blue - yellow axis. A ΔE < 1 is generally imperceptible. A ΔE > 5 represents a clearly visible difference.

Reference Data

Condition	Type	Prevalence (Male)	Prevalence (Female)	Affected Cones	Confused Hues
Normal Trichromacy	Normal	92%	99.5%	None	None
Protanomaly	Anomalous Trichromacy	1.3%	0.02%	L (red)	Red - Green
Protanopia	Dichromacy	1.0%	0.02%	L (red) absent	Red - Green
Deuteranomaly	Anomalous Trichromacy	5.0%	0.35%	M (green)	Red - Green
Deuteranopia	Dichromacy	1.2%	0.01%	M (green) absent	Red - Green
Tritanomaly	Anomalous Trichromacy	0.01%	0.01%	S (blue)	Blue - Yellow
Tritanopia	Dichromacy	0.003%	0.003%	S (blue) absent	Blue - Yellow
Achromatopsia	Monochromacy	0.003%	0.003%	All cones	All hues
Tetrachromacy	Enhanced	Rare	~12% carriers	Extra L variant	None (superior)
Cone Type S	Photoreceptor	Peak 420nm		Short wavelength	Blue - Violet
Cone Type M	Photoreceptor	Peak 534nm		Medium wavelength	Green
Cone Type L	Photoreceptor	Peak 564nm		Long wavelength	Red - Orange
Visible Spectrum	Range	380 - 700nm		All cones	-
Just Noticeable Difference	JND (Hue)	1 - 3°		-	Best at 490 & 580nm
D65 Illuminant	Standard	6504K		-	Clinical reference white

Frequently Asked Questions

Ambient light alters perceived hue and saturation by adding a spectral bias to your monitor's output. Warm incandescent light (~2700 K) shifts blues toward gray and boosts apparent yellow-red saturation, inflating your error score in the blue-cyan region. For valid results, test under neutral daylight or D65-calibrated lighting. Avoid direct sunlight on your screen. Clinical Farnsworth-Munsell tests mandate a D65 light booth with illuminance between 270 and 1340 lux.

Yes. A 6-bit TN panel with dithering (common in budget monitors) produces visible banding in smooth gradients that an 8-bit or 10-bit IPS panel would render smoothly. If you see hard bands, try the test on a different display before concluding your eyes are at fault. Your GPU color output depth (check display settings for 8-bit vs 10-bit) also matters.

In the Farnsworth-Munsell D-15 protocol, a TES of 0 is perfect. Scores below 20 (on a 15-chip test) indicate normal trichromacy. Scores between 20 and 40 suggest mild anomalous trichromacy. Scores above 56 suggest dichromacy. This tool uses a proportional scale: your percentage score maps inversely to the TES - 100% means zero errors, 0% means maximum displacement across all chips.

The genes encoding L-cone (OPN1LW) and M-cone (OPN1MW) opsins sit adjacent on the X chromosome at Xq28, making them vulnerable to unequal recombination during meiosis. Males with one X chromosome express any resulting mutation. S-cone opsin (OPN1SW) is encoded on autosomal chromosome 7, requiring two defective copies for full tritanopia, which is statistically rarer.

No. Tetrachromacy involves a fourth cone type with peak sensitivity between the standard L and M cones. Detecting it requires stimuli that differ only in spectral composition while matching in tristimulus values (metameric pairs). Standard RGB monitors cannot produce such stimuli because they output only three primaries. Tetrachromacy detection requires a spectrophotometer-driven anomaloscope or specialized Rayleigh match testing.

Chips are generated at equal hue intervals across a defined range (e.g., 15 chips spanning 60° of hue). They are shuffled randomly. You drag them into what you perceive as the correct gradual order. The algorithm then computes the circular hue difference between each chip's placed position and its target position, sums these differences, and normalizes against the theoretical maximum error to produce a 0-100% score.