Methodology
Color-vision simulation helps reveal palette risks, especially when color is the only cue. Hue Codex treats it as a screening tool, not a substitute for real user testing.
Hue Codex applies fixed RGB transform matrices for protanopia, deuteranopia, tritanopia, and achromatopsia, then compares simulated swatches with Delta E style distance and WCAG text checks.
These badges identify which parts of this methodology are standards-backed, draft-track, Hue Codex-specific, approximate, or dependent on browser behavior.
This separates standards-based formulas from Hue Codex implementation decisions, product heuristics, and known limitations for this methodology.
Formula, threshold, syntax, or data behavior taken from a cited standard or standards-backed source.
How Hue Codex chooses to parse, normalize, round, export, or sequence calculations.
Product rankings, bands, labels, suggestions, or role hints that are useful guidance but not external standards.
Caveats, edge cases, browser dependencies, approximations, or contexts the method does not prove.
Hue Codex includes protanopia, deuteranopia, tritanopia, and achromatopsia modes. The selected matrix is applied to each sRGB color and the result is clamped back to displayable sRGB.
Duplicate HEX values are removed before pair comparison so the review focuses on distinct palette entries.
For each pair, Hue Codex calculates original Delta E 76 and simulated Delta E 76. A pair is flagged as likely collapse below 4, needs non-color cues below 8, review in context below 14, and distinct signal at higher distances.
Hue-only risks are pairs that begin visually separated but become close under the selected simulation. These are especially important for charts, status indicators, and selected states.
Each simulated swatch receives a best black/white/text-candidate recommendation and WCAG contrast score. This catches cases where a simulated color remains distinct but becomes a poor surface for text.
| Check | Expected behavior |
|---|---|
| Two identical colors | Pair ranks as collapse risk |
| Red/green-heavy pairs in red-green modes | Review or collapse risk is likely |
| Achromatopsia mode | Output depends primarily on lightness |
| Export caveat | Reports state that simulation is approximate |
Hue Codex applies fixed matrices directly to encoded 8-bit sRGB channels, then rounds and clamps back to displayable sRGB. It does not linearize before these matrix transforms.
matrices:
protanopia =
[[0.567, 0.433, 0 ],
[0.558, 0.442, 0 ],
[0, 0.242, 0.758]]
deuteranopia =
[[0.625, 0.375, 0 ],
[0.700, 0.300, 0 ],
[0, 0.300, 0.7]]
tritanopia =
[[0.950, 0.050, 0 ],
[0, 0.433, 0.567],
[0, 0.475, 0.525]]
achromatopsia =
[[0.299, 0.587, 0.114],
[0.299, 0.587, 0.114],
[0.299, 0.587, 0.114]]
simulate(hex, matrix):
r, g, b = hex_to_rgb(hex) # encoded sRGB 0..255
r2 = r*matrix[0][0] + g*matrix[0][1] + b*matrix[0][2]
g2 = r*matrix[1][0] + g*matrix[1][1] + b*matrix[1][2]
b2 = r*matrix[2][0] + g*matrix[2][1] + b*matrix[2][2]
return rgb_to_hex(round_and_clamp(r2, g2, b2))
rank_pair_risks(colors, mode):
entries = unique colors mapped to simulated HEX
for each unordered pair:
original_delta = delta_e_76(original_a, original_b)
simulated_delta = delta_e_76(simulated_a, simulated_b)
label = simulated_delta < 4 ? collapse
: simulated_delta < 8 ? non_color_cues
: simulated_delta < 14 ? review
: distinct
sort pairs by simulated_delta ascending
hue_only_risk = original_delta >= 12 and simulated_delta < 8These vectors validate the fixed RGB transform matrices and final sRGB clamping used by the simulator.
| Input | Expected output | Notes |
|---|---|---|
| Protanopia matrix applied to #FF0000 | #918E00 | Matrix result rounded and clamped to sRGB |
| Deuteranopia matrix applied to #FF0000 | #9FB300 | Matrix result rounded and clamped to sRGB |
| Tritanopia matrix applied to #0000FF | #009186 | Matrix result rounded and clamped to sRGB |
| Achromatopsia matrix applied to #4169E1 | #6B6B6B | Equalized grayscale-style RGB result |
These references anchor the public standards and formats used by Hue Codex. Status badges distinguish stable standards, drafts, Hue Codex heuristics, approximations, and browser-dependent behavior.
These Hue Codex tools link to this methodology because they depend on the formulas, assumptions, limits, or data policy described here.