Protanomaly Simulator

Protanomaly Simulator previews a color as a viewer with reduced red sensitivity would see it, applying the complete protanopia projection as a conservative check.

What is Protanomaly Simulator?

Protanomaly Simulator previews a color for a viewer whose sensitivity to the long-wavelength cone is reduced rather than absent. The page shows the original and the simulated result as a large pair, which makes it the quickest way to see how much of a red survives when the red channel stops contributing as it usually does.

Protanomaly sits on the same axis as protanopia, so the two are often grouped, but there are real differences in what a design should expect:

• Red sensitivity is reduced rather than missing, so reds lose vividness progressively rather than collapsing at once.
• Protanomaly prevalence among men is around one in a hundred, which makes it markedly less common than the green anomaly but still far more common than the complete form.
• Red also loses some luminance, which is the reason this page is worth separating from the green anomaly: a dark red becomes harder to see, not merely duller.
• Where a viewer sits between typical color vision and a complete protan view varies widely, so a single simulated swatch cannot represent the group.

The swatch is produced by the same matrix the protanopia page uses, applied directly to the 8-bit red, green and blue channels: 0.567 red plus 0.433 green on the first row, 0.558 red plus 0.442 green on the second, and 0.242 green plus 0.758 blue on the third, with results clamped into the 0 to 255 range before being written out as hex. That matrix models the complete deficiency at full strength. What appears on the right is therefore the severest case for this cone rather than a graded partial view, and the gap between that and a typical viewer with the anomaly is the single most important thing to know about this page.

The limits follow from the same source.

• No severity control, so the partial range the page is named for cannot be reproduced.
• One color per comparison, with no palette or image mode.
• The simulated result is a complete-deficiency projection, which is generally harder than the anomaly itself.
• The hex value describes the model, not a prediction of what a particular viewer will see.
• Nothing is measured from a real display, so panel differences are not reflected.

Use it as the strict version of a red check. Alerts, negative states, required-field markers and any red-versus-green pairing are the places it earns its keep, and the question to ask of the simulated swatch is whether it still separates from its neighbours in lightness once red has contributed as little as the matrix allows. If it does, someone with the partial form will see at least as much separation, because their red channel is still doing some work.

The naming is worth disentangling, because it shapes how the result should be used. Partial red blindness describes the audience the page is aimed at, while the conversion itself is the complete matrix, so red weakness appears at its limit rather than at the milder level most affected viewers experience. Read that way the swatch sets a floor: anything that still separates under it will separate for everyone whose red sensitivity is reduced by less.

How to use Protanomaly Simulator

1. Set the color you want previewed in the swatch field.
2. Read the two swatches together, checking how much the red has lost in both saturation and lightness.
3. Note the hex value printed for the simulated result if the conversion needs recording.
4. Compare that result against the other colors it will appear with, and widen the lightness gap if it has become hard to separate.

When to use Protanomaly Simulator vs related tools

Use the protanomaly simulator when red carries meaning and you want the conservative end of the partial red deficiency covered in one check. The fully protanopic view is the protanopia simulator, the green counterpart is the deuteranomaly simulator, a screen rather than a single color is better handled by the color blindness simulator, and text that has to remain legible after the conversion is the subject of the text readability checker.

Privacy & Security

This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.

Frequently asked questions about Protanomaly Simulator