About colorblind
colorblind is a collection of on-device vision tools based on a published color-vision simulation method. It serves developers and people exploring vision tests, with image simulation, palette checks, and test plates; images are not uploaded.
Key features
- 01Simulate images for different color deficiencies
- 02Offer 17 vision tests
- 03Generate Ishihara test plates
- 04Check palettes for color-vision safety
- 05Explain online test methods and limitations
Use cases
- 01Preview images under different color deficiencies
- 02Check chart palettes for color-vision accessibility
- 03Create Ishihara plates for exploration or demonstrations
MCP support
The README mentions the related cvdsafe-mcp and colorblind-mcp servers, which let assistants check palettes or generate Ishihara plates.
Configuration
Local server config is the same for every client. Copy it into your client’s MCP config file.
Tools
4Saved tool list · updated 2w ago
| Parameter | Type | Required | Description |
|---|---|---|---|
| type | enum | Yes | Color-vision deficiency typeprotan | deutan | tritan |
| color | string | Yes | Hex color, e.g. #d7191c |
| severity | number | No | Deficiency strength 0..1 (default 1) |
Details
From the project README╔════════════════════════════════════════════════════════════════════════════════════════════╗
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║ your eyes, tested in the browser, with nothing leaving it ║
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An open, published method for color vision — and 17 vision tests built on it. Everything runs on the device. No account, no upload, no image ever sent anywhere.
The colorimetry is not a private formula: it is Machado, Oliveira & Fernandes (2009) deficiency simulation with CIEDE2000 color difference, published open access at doi.org/10.5281/zenodo.21310578, and shipped as packages so you can run the math yourself and check our numbers against yours.
Use the engine
pip install cvdsafe # is this palette colorblind-safe?
npm install cvdsafe
import cvdsafe
cvdsafe.is_safe(["#d7191c", "#1a9641"]) # False — red and green collapse under deutan
npx cvdsafe "#d7191c" "#1a9641" # exits 2 if the palette is unsafe — CI-friendly
| what you want | package |
|---|---|
| Is this palette safe? | cvdsafe · npm + PyPI, with a CLI |
| Show me how it looks | cvdsim — recolors an image for protan/deutan/tritan |
| Give me safe colors | safepalette — Okabe–Ito, extended and verified |
| For matplotlib | cvdmaps — set_cycle() and you're safe |
| Make test plates | cvdplate · ishihara |
| Acuity math | logmar — logMAR ↔ Snellen ↔ decimal |
| One deficiency | protan · deutan · tritanopia · dichromacy · achromatopsia · trichromacy |
For LLM tools: cvdsafe-mcp and colorblind-mcp are MCP servers, listed in the official
Model Context Protocol registry — so an assistant can check a palette or generate an Ishihara
plate as a native tool.
The tests
Color vision, D-15 arrangement, hue discrimination, anomaloscope-style matching, contrast sensitivity, acuity, astigmatism, Amsler grid, blind spot, vernier alignment, flicker fusion, saturation, dominance, reaction, stereo depth, digital eye strain, and a shape-based test for kids.
A test on a web page cannot be a diagnosis: an uncalibrated display, ambient light and viewing distance all move the result. Each test says so where it reports, and points at an eye examination rather than standing in for one.
Audit it yourself. opticquiz.com/methodology answers the eight questions worth asking of any online vision test — who made it, what it measures, what it assumes about your screen, whether it has been clinically validated (it has not), what it cannot measure, and who pays for it.
Also in here
Translations (de, es, fr, hi, it, pt, zh), a browser extension (reviewed and listed by Mozilla),
a VS Code extension, a Figma plugin, an embeddable widget, and the research notes behind the
plate colors under research/.
MIT licensed. Issues and corrections welcome — if a number here disagrees with yours, that is a bug worth reporting.
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║ · C R E A T I V E · ║
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║ Vincent Gonzalez ║
║ f-keys.com ║
║ ORCID 0009-0005-3640-014X ║
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Part of F-Keys — independent hardware, software and internet products. See the working log and live status.
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