Color-Blind Safe Palette Band Check

Audit all palette pairs in OKLab after three explicit dichromacy model simulations against caller distance threshold; this model screen is not a color-blind-safe guarantee, luminance contrast test or individual visual diagnosis.

Description

Palette distance under three dichromacy simulations provides a model-based separation screen.

Palette distance under three dichromacy simulations provides a model-based separation screen. It cannot guarantee accessibility for every viewer.^{[1, 2]}

Enter 2–128 normalized RGB rows and nonnegative distance threshold. Simulate full protan,deutan,tritan models, convert clipped outputs to OKLab and return minima in that order plus strict-below-threshold flags.

When to use Color-Blind Safe Palette Band Check

Use Color-Blind Safe Palette Band Check when you need to evaluate the supplied records under the calculation and evidence rules below. No individual diagnosis, luminance-contrast test or color-blind-safe guarantee is provided.

Prepare colors in the stated color space and scale. Use encoded RGB fractions, linear RGB, Lab, xy, byte values or ink percentages exactly as requested; supply caller tolerances and reference conditions.

How to use Color-Blind Safe Palette Band Check and understand its results

Prepare colors in the stated color space and scale. Use encoded RGB fractions, linear RGB, Lab, xy, byte values or ink percentages exactly as requested; supply caller tolerances and reference conditions.
Enter paletteRgbRows, callerMinimumSimulatedOklabDistance using the field table and calculation rules, then run the tool.
Read minimumProtanDeutanTritanDistances, belowCallerDistancePolicyFlags. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
paletteRgbRows	Palette rgb rows	list of list of number	Required
callerMinimumSimulatedOklabDistance	Caller minimum simulated oklab distance	number	Required

minimum[type]=min(all pairwise OKLab distances after simulation)

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
minimumProtanDeutanTritanDistances	Minimum protan deutan tritan distances	list of number
belowCallerDistancePolicyFlags	Below caller distance policy flags	list of number

json

{
  "input": {
    "paletteRgbRows": [
      [
        0,
        0,
        0
      ],
      [
        1,
        1,
        1
      ]
    ],
    "callerMinimumSimulatedOklabDistance": 0.1
  },
  "output": {
    "minimumProtanDeutanTritanDistances": [
      0.9999999934735468,
      0.9999997761596604,
      0.9999999934735468
    ],
    "belowCallerDistancePolicyFlags": [
      0,
      0,
      0
    ]
  }
}

Limitations and assumptions

No individual diagnosis, luminance-contrast test or color-blind-safe guarantee is provided.

Numeric inputs, where present, must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Matrices are limited to 128 rows and 128 entries per row. Numeric lists are limited to 10,000 entries; string lists to 128 strings of at most 128 characters each. The rules above may impose smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Protanopia Simulation Matrix: A protanopia visualization applies a published full-severity model in linear sRGB. Clipping remains visible in the returned evidence. For a complementary task, use Categorical Minimum Delta-E Pairwise: Categorical color separation can be audited across every palette pair. CIE 76 uses Euclidean distance in one Lab reference frame.

Further background: A physiologically-based model for simulation of color vision deficiency (2009).

References

Color-Blind Safe Palette Band Check — tool.io
A physiologically-based model for simulation of color vision deficiency (2009) — Machado, Oliveira and Fernandes

Similar or alternative tools

Protanopia Simulation Matrix
A protanopia visualization applies a published full-severity model in linear sRGB. Clipping remains visible in the returned evidence.
Categorical Minimum Delta-E Pairwise
Categorical color separation can be audited across every palette pair. CIE 76 uses Euclidean distance in one Lab reference frame.