Tritanopia Simulator

Tritanopia Simulator shows a color beside the same color as a tritanopic viewer would see it, modelling the rarer blue-yellow deficiency.

What is Tritanopia Simulator?

Tritanopia Simulator renders a color and its tritanopic simulation side by side, in the same large two-swatch layout the other single-deficiency pages use. It is the page to reach for when a design depends on blue and yellow, which is the axis the two common red-green deficiencies leave untouched.

Tritanopia is the absence of the short-wavelength cone, and it behaves differently enough from the red-green deficiencies that it is worth understanding on its own terms:

• Blue and yellow converge, so a blue and a green can become difficult to separate while red stays comparatively distinct.
• Blue darkens, in the same way red darkens under protanopia, because the cone being removed contributes luminance at that end of the spectrum.
• Yellow is affected as well, which is why the deficiency is described as a blue-yellow condition rather than a blue one.
• It is far rarer than the two red-green types, so a palette that is only tested for those can still fail a small but real group of viewers.

The simulated color is produced by a fixed three-by-three matrix over the 8-bit red, green and blue channels. Its first row is 0.95 red plus 0.05 green, its second is 0.433 green plus 0.567 blue, and its third is 0.475 green plus 0.525 blue, with the outputs clamped inside the 0 to 255 range and written out as hex. Note how little the red channel changes: the transformation is concentrated in the green and blue rows, which is the arithmetic reason the red-green axis survives better than the blue-yellow one here. As with the other pages, the matrix approximates the deficiency and is applied at full strength.

A few things sit outside this page.

• One deficiency only, with no combined view and no image simulation.
• A single color per comparison, so a palette takes one pass per entry.
• No severity control, which matters because acquired tritan-like deficiencies are often partial rather than complete.
• The output is a model, not a prediction about a particular viewer.
• No export beyond copying the hex value that is printed.

Use it whenever blue and yellow are doing structural work: a two-series chart, a warm and cool status pair, or a gradient that runs from blue to yellow as a way of showing magnitude. Read the simulated swatch for two things, whether it has moved toward the greens in your set, and whether it has lost enough lightness to merge with its background. Both are common failures in this deficiency, and both are easier to correct by separating lightness than by searching for a hue that survives.

This is a blue cone simulation and nothing more, which is worth saying because the page is easy to over-read. The tritanopia hex value under the simulated swatch is what you take away from it, together with a view of how far a blue has moved. Set beside the more familiar red-green checks, it also makes the case for treating blue yellow color blindness as its own problem: a design can pass every red-green review and still lean on a blue and a yellow that this conversion pushes close together.

How to use Tritanopia Simulator

1. Enter the color you want simulated in the swatch field.
2. Compare the original swatch with the tritanopic simulation beside it, looking at blues and yellows in particular.
3. Read the hex value printed under the simulated swatch to record how the color was changed.
4. Check whether the simulated result has drifted toward the greens or lost lightness against the surfaces it will sit on.

When to use Tritanopia Simulator vs related tools

Use the tritanopia simulator when blue and yellow carry meaning in a chart, a gradient or a status pair, since that is the axis this deficiency attacks and the one the red-green tools do not cover. Charts that depend on several hues benefit from the full color blindness simulator, blue-heavy palettes are worth checking against the palette accessibility checker, and choosing text colors that survive any of these conversions is the color blind friendly color picker.

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 Tritanopia Simulator