Protanopia color simulator

Enter a hex value or integer RGB channels and receive normalized source and simulated values in both formats. The calculation is deterministic: it linearizes sRGB, applies a fixed Brettel-Vienot-Mollon projection matrix, clamps the result to the displayable gamut, and encodes it back to eight-bit sRGB. It is useful for repeatable design reviews, automated token checks, documentation, and educational demonstrations, while remaining a simulation rather than a medical assessment.

Use the simulator to inspect a specific interface color

Start with the exact sRGB value used by your design system, stylesheet, chart, or exported asset. The input may be a three-digit or six-digit hexadecimal color, a CSS-style rgb() expression, or three comma-separated integer channels. The response includes a normalized source color as well as the simulated hex and RGB values, so it can move directly into a design note, test fixture, or comparison tool. Treat the transformed swatch as evidence about appearance, not as a pass or fail accessibility verdict. Protanopia can make colors that differ strongly for many viewers appear closer, but usability also depends on contrast, size, surrounding colors, labels, patterns, and interaction states. A red warning and green confirmation should therefore have distinct text or icons even if this simulation suggests an obvious visual difference. For systematic review, run each semantic token separately and compare related states under the same method. Keeping the method fixed matters: mixing outputs from unrelated simulation formulas can create apparent differences caused by the tools rather than by the colors themselves.

Understand the deterministic color pipeline

The calculation begins by validating and normalizing the supplied color into three eight-bit sRGB channels. Those stored channel values are gamma encoded, so the simulator first converts them to linear-light values. It then multiplies the linear triplet by a fixed three-by-three projection associated with the Brettel, Vienot, and Mollon approach to dichromatic color-vision simulation. Matrix multiplication can produce values outside the displayable sRGB interval, especially for highly saturated inputs. Each projected channel is therefore clamped to the closed interval from zero to one before the standard sRGB encoding function is applied. Finally, the encoded values are rounded to the nearest integer and formatted as RGB and lowercase hexadecimal output. Every step is bounded and uses no network request, random value, clock, user profile, or hidden adaptive setting. The same valid input consequently produces the same JSON result. This reproducibility makes the endpoint suitable for snapshots and regression checks. It also makes the method explicit: a different color space, gamut-mapping policy, severity model, or matrix may legitimately produce a different result and should be documented as a different simulation.

Interpret results responsibly in accessibility work

Use the result as one lens in a broader review. A protanopia simulation can reveal that a red series and a dark green series converge, that a destructive button loses its expected emphasis, or that status chips depend too heavily on hue. When that happens, improve the original interface rather than attempting to optimize only the simulated hex value. Add redundant cues such as labels, icons, line styles, shapes, borders, or spatial separation, and verify text and component contrast using the accessibility standard relevant to your product. Test complete states, including hover, focus, disabled, selected, error, and success appearances, because a palette that works in a static legend may fail during interaction. The simulator models a color transformation, not the variation among individuals, displays, ambient conditions, or viewing contexts. It does not measure visual acuity, diagnose protanopia, predict personal perception, or certify compliance. Human evaluation remains valuable for consequential products. In automated workflows, store the source color, simulated output, named method, and the decision made from the review; that audit trail prevents a transformed swatch from being mistaken later for an original brand token.