Question 1

What are the main types of color blindness?

Accepted Answer

Three axes of cone deficiency: protan (red cones missing or shifted, ~1% of men), deutan (green cones missing or shifted, ~6% of men, the most common), and tritan (blue cones missing or shifted, ~0.001%, very rare). Each axis has a complete form (-opia, no cones of that type) and an anomalous form (-anomaly, shifted sensitivity). Achromatopsia is total color blindness, only rods, no cones, extremely rare.

Question 2

How does the simulation actually work?

Accepted Answer

Each deficiency has a published linear transformation in LMS color space (long-medium-short cone responses). The tool converts sRGB → linear RGB → LMS, applies the deficiency matrix, then reverses the chain back to sRGB. The most commonly cited matrices come from Brettel/Viénot/Mollon (1997) and Machado/Oliveira/Fernandes (2009). Quality is good for dichromacy, approximate for anomalous trichromacy.

Question 3

What should I actually look for in the simulated output?

Accepted Answer

Three classic failure modes: (1) red/green status indicators (success/error icons) that collapse to the same hue, (2) chart series using only color to distinguish categories, (3) form errors marked only by a red outline. The fix in all three cases is redundancy, pair color with shape, icon, or text label.

Question 4

Does WCAG require color-blindness testing?

Accepted Answer

WCAG 2.1 doesn't mandate simulation, but Success Criterion 1.4.1 (Use of Color, Level A) requires that color not be the only means of conveying information. Simulators are how you find violations. The 4.5:1 contrast requirement (1.4.3) helps but isn't sufficient, high-contrast red on green is still indistinguishable to a deuteranope.

Question 5

How accurate are these simulations?

Accepted Answer

Reasonably accurate for what an outsider sees, less accurate as a lived experience. People with congenital color blindness have adapted their entire visual learning to their cones, their brains compensate in ways the matrix can't model. Use simulations to identify problems, not to claim 'this is what they see.'

Question 6

What's the difference between dichromacy and anomalous trichromacy?

Accepted Answer

Dichromacy (-opia): missing one cone type entirely. Two-axis color vision. Anomalous trichromacy (-anomaly): all three cones present, but one is shifted in spectral sensitivity. Color discrimination is reduced along that axis but not absent. Anomalous forms are roughly 4× more common than complete forms.

Question 7

Are images uploaded to a server?

Accepted Answer

No. Image processing uses the Canvas API and pixel-level matrix multiplication, all in your browser. Large images may take a second on lower-end devices because each pixel goes through a 3×3 transform, but nothing leaves your machine.

Question 8

What standards does Color Blindness Simulator validate against?

Accepted Answer

Color Blindness Simulator checks compliance with Brettel/Vióllaz simulation model, WCAG 2.2.

Question 9

What are the limitations of Color Blindness Simulator?

Accepted Answer

Simulation is approximate, does not perfectly replicate all types of color vision deficiency Does not test contrast ratios under simulated vision Limited to common CVD types

Type	Cone Deficiency	Prevalence (M/F)	Core Visual Impact
Deuteranopia	Medium (Green)	1% / 0.01%	Red/Green collapse
Protanopia	Long (Red)	1% / 0.02%	Red dimming / collapse
Tritanopia	Short (Blue)	< 0.01%	Blue/Yellow collapse
Achromatopsia	All Cones	< 0.001%	Total grayscale vision

Color Blindness Simulator

What is Color Blindness Simulator?

Frequently Asked Questions

Technical Deep Dive

Color Blindness Simulator

Pixel-Precise Output

Live Visual Preview

Copy-Paste Ready

01 Color Vision Deficiency (CVD) Matrix

02 Simulation Logic Pipeline

Runs 100% in your browser

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