Which algorithm does the simulator use?

It uses the Machado et al. (2009) sRGB transformation matrices at full severity — the same approach used by Chrome DevTools. Colours are gamma-decoded to linear RGB, multiplied by the deficiency matrix, then gamma-encoded back to sRGB.

Is my colour data uploaded?

No. All simulation maths happens locally in your browser. Nothing about the colour you enter is sent to any server.

What are protanopia, deuteranopia and tritanopia?

They are types of colour blindness. Protanopia is the absence of red cones, deuteranopia the absence of green cones (both cause red-green confusion), and tritanopia the absence of blue cones (blue-yellow confusion). Achromatopsia is total colour blindness, seeing only greyscale.

How accurate is the simulation?

It is a well-established scientific approximation suitable for design and accessibility checks, but it is not a medical diagnosis. Colour vision varies between individuals, so use it as guidance, not a definitive test.

Color Blindness Simulator

This tool shows how a colour appears to people with the most common colour vision deficiencies — protanopia, deuteranopia, tritanopia and full achromatopsia. Enter a colour and compare side by side how it looks to typical vision versus each deficiency, so you can check whether a palette stays distinguishable for colour-blind users.

How it works

The simulator uses the Machado et al. (2009) sRGB transformation matrices at full severity — the de-facto standard, also used by Chrome DevTools. For each deficiency it runs this pipeline: the input colour is gamma-decoded from sRGB to linear RGB, multiplied by that deficiency’s 3×3 matrix to remap the channels as the missing cone type would, then gamma-encoded back to sRGB. Achromatopsia instead collapses the colour to its luminance, producing grey.

Type	Affected cones	Confusion
Protanopia	red	red-green
Deuteranopia	green	red-green
Tritanopia	blue	blue-yellow
Achromatopsia	all	none (greyscale)

Example

A pure red (#ff0000) appears as a dull yellow-brown under protanopia and deuteranopia, because the red signal is remapped without a red cone, and as mid-grey under achromatopsia. This reveals why red-on-green warnings can be invisible to many viewers. All processing happens locally in your browser; nothing is uploaded.