Simulate how colours appear under a colour-vision deficiency

Maps each colour to the colour a reader with a given form and severity of colour-vision deficiency would perceive, using the physiologically-based model of Machado, Oliveira and Fernandes (2009). The transformation is defined on linear-light RGB, so a colour is decoded from sRGB to linear RGB (the IEC 61966-2-1 transfer functions), transformed, then re-encoded.

Usage

simulate_cvd(colours, deficiency, severity = 1)

Arguments

colours

Character vector of colours, in any form grDevices::col2rgb() understands.

deficiency

The deficiency to simulate: "protan" or "deutan" (the two red-green forms) or "tritan" (blue-yellow).

severity

Severity in [0, 1]. Zero leaves the colours unchanged and one is the full deficiency. Intermediate values interpolate the transform towards the identity, an approximation to Machado et al.'s per-severity matrices.

Value

A character vector of lower-case hex colours, the same length as colours.

Details

This is the simulator behind palette_preview()'s cvd argument, behind palette_safety(), and behind the colour-separability rows of check_figure().

References

Machado GM, Oliveira MM, Fernandes LAF (2009). “A physiologically-based model for simulation of color vision deficiency.” IEEE Transactions on Visualization and Computer Graphics, 15(6), 1291–1298. doi:10.1109/TVCG.2009.113 .

Examples

simulate_cvd(c("#005b96", "#e69f00"), "deutan")
#> [1] "#275295" "#cab411"

# Half severity moves the colours only part of the way.
simulate_cvd(c("#005b96", "#e69f00"), "deutan", severity = 0.5)
#> [1] "#1a5795" "#d8aa09"