How a color would appear under one specific vision type
A vivid red-pink (#E11D48) simulated under protanopia (red-blindness) shifts to an olive/khaki tone (#8c8a3e) -- a dramatic transformation that illustrates why relying on red as a sole visual signal (like a red 'error' state) can fail entirely for someone with this specific color vision difference.
Protanopia specifically involves an absence of functioning red-sensing cone cells in the eye -- this simulation applies a color transformation matrix that models how colors would be perceived without that red-sensing input, which is why the original vivid red shifts toward a muddier, yellow-green tone rather than simply appearing 'less bright.'
Different types of color blindness (protanopia, deuteranopia, tritanopia) each involve a different missing or altered cone type, and would transform this same #E11D48 red differently -- switching the simulation type shows a genuinely different resulting color, not just a variation on the same shift.
Why this is a planning tool, not a diagnostic one
Planning matrices, not a clinical diagnostic. Preview paints the simulated swatch. This uses well-established color transformation matrices commonly used for design and accessibility planning -- useful for checking whether a color choice remains distinguishable, but not a medically validated diagnostic tool for actually testing or diagnosing someone's color vision.
Real-world color blindness also varies in severity between individuals even within the same type (protanopia specifically is complete red-cone absence, while protanomaly is a milder reduced-sensitivity version) -- this simulator models the complete/severe version of each type, which represents one end of a real spectrum of color vision variation.
The practical takeaway from a dramatic shift like this example is usually not to avoid red entirely, but to avoid relying on color alone to convey important information -- pairing color with an icon, label, or pattern ensures the information still gets across even when a specific color becomes hard to distinguish.
Related color-accessibility tools
For suggestions on building an entire palette that stays distinguishable across color vision types from the start, the Colorblind-Safe Palette Suggester is a more proactive companion tool.
For checking contrast ratio (a related but different accessibility concern from color-vision distinguishability), the Color Contrast (WCAG) Checker covers that separately.
Frequently Asked Questions (FAQ)
Why does #E11D48 shift so dramatically to an olive tone under protanopia?
Protanopia involves a complete absence of functioning red-sensing cone cells. The simulation applies a color transformation matrix modeling perception without that red-sensing input, which shifts a vivid red toward a muddier, yellow-green tone rather than simply dimming it.
Would a different type of color blindness transform this same red differently?
Yes. Protanopia, deuteranopia, and tritanopia each involve a different missing or altered cone type, and each would produce a genuinely different simulated color for the same original red -- not just a variation on the same shift.
Is this simulator a clinical diagnostic tool for color blindness?
No. Planning matrices, not a clinical diagnostic. Preview paints the simulated swatch. It uses established color transformation matrices for design and accessibility planning purposes. It isn't a medically validated tool for testing or diagnosing an individual's actual color vision.
Does this account for milder forms of color vision deficiency, like protanomaly rather than full protanopia?
Planning matrices, not a clinical diagnostic. Preview paints the simulated swatch. No, this simulates the complete/severe version of each type (like full protanopia). Real color vision deficiency varies in severity between individuals, and this represents one end of that spectrum, not every possible degree of the condition.
What should I actually do if a color shift like this shows up in my design?
Rather than avoiding the color entirely, pair it with an additional visual signal -- an icon, label, or pattern -- so the information it conveys still comes through even for someone who can't distinguish that specific color from others around it.
