How do I make a palette color-blind friendly?

Keep the pairs far apart in lightness, not just hue. A dark red and a light green stay distinguishable in every simulation; two mid-tone colors of similar brightness do not. Adding a label, icon or pattern removes the dependency on color entirely.

Is my image uploaded anywhere?

No. The image is read with FileReader, drawn to a canvas and simulated pixel by pixel in your browser. Nothing is sent to a server.

Does this replace a contrast check?

No, they answer different questions. Contrast measures how readable a text and background pair is; this measures whether two colors are still distinguishable from each other. Use the contrast checker as well.

Color Blindness Simulator

Paste a palette or upload an image to see it through protanopia, deuteranopia, tritanopia and achromatopsia. Everything is simulated locally with the Machado, Oliveira & Fernandes matrices — your image never leaves the browser.

Palette — up to eight hex codes, separated by commas or spaces

#DC143C, #50C878, #FFD700, #0EA5E9, #7C3AED, #808080

Or simulate an image

Choose an image (PNG, JPG, WebP, SVG)

Your palette, simulated

Normal vision

Standard trichromatic vision, shown for reference.

#DC143C#DC143C
#50C878#50C878
#FFD700#FFD700
#0EA5E9#0EA5E9
#7C3AED#7C3AED
#808080#808080

Protanopia

Red-blind. Reds look darker and can be confused with greens and browns.

#DC143C#5c553b
#50C878#c9b872
#FFD700#f0d300
#0EA5E9#84a5ec
#7C3AED#0069f2
#808080#808080

Deuteranopia

Green-blind. Greens look muted and can be confused with reds and browns.

#DC143C#8b7e35
#50C878#b9ad7d
#FFD700#fadf24
#0EA5E9#6893e8
#7C3AED#0063ea
#808080#808080

Tritanopia

Blue-blind. Blues look greenish and yellows fade toward pink.

#DC143C#f20029
#50C878#2ac5b4
#FFD700#ffc4b7
#0EA5E9#00b6bd
#7C3AED#586c92
#808080#808080

Achromatopsia

Complete color blindness. Everything is seen in shades of gray.

#DC143C#6f6f6f
#50C878#b2b2b2
#FFD700#dadada
#0EA5E9#9b9b9b
#7C3AED#676767
#808080#808080

Roughly one in twelve men and one in two hundred women live with some form of color vision deficiency, so a palette that separates cleanly for you may collapse into two greys for a large slice of your audience. This simulator applies the Machado, Oliveira & Fernandes severity-1.0 matrices to each color, which is the same model used in vision research, and renders complete achromatopsia as a luminance grayscale. The rule of thumb it makes visible: never let color alone carry meaning — pair it with lightness, shape or a label.

Frequently asked questions

Protanopia is red-blindness, deuteranopia is green-blindness and tritanopia is blue-blindness. Deutan and protan types are the most common and both make reds, greens and browns harder to separate; tritanopia is rare and shifts blues toward green and yellows toward pink.

Good to know

Simulation uses the Machado, Oliveira & Fernandes (2009) matrices in linear sRGB.
Every simulated hex code is copyable, so you can test the result in your own design.
Image processing is capped at 640px wide for speed and stays entirely local.