Discrimination Ellipse

A region in a color space surrounding a given color within which other colors cannot be distinguished from it by an observer. In two dimensions this region forms an ellipse; in three-dimensional color spaces it becomes an ellipsoid. The size and shape of discrimination ellipses vary across the color space and differ between individuals, particularly those with color vision deficiencies. In accessibility, discrimination ellipses are used to model individual color differentiation ability — colors falling inside a person's ellipse for a given base color will appear identical to them, which informs recoloring tools that adapt digital content for people with color vision deficiencies.