contrast

func Darker ¶

func Darker(tone, ratio float64) float64

Darker returns a tone less than or equal to the given tone that satisfies the specified contrast ratio.

The returned value is in the range [0, 100]. Returns -1 if the desired contrast ratio cannot be achieved with the input tone.

tone must be in the range [0, 100]. Invalid values result in -1. ratio should be in the range [1, 21]; invalid values have undefined behavior.

func DarkerUnsafe ¶

func DarkerUnsafe(tone, ratio float64) float64

DarkerUnsafe returns a tone less than or equal to the given tone that attempts to satisfy the specified contrast ratio.

The returned value is always in the range [0, 100]. Returns 0 if the desired contrast ratio cannot be achieved. Unlike Darker, this function does not fail but may not always satisfy the desired contrast ratio.

func Lighter ¶

func Lighter(tone float64, ratio float64) float64

Lighter returns a tone greater than or equal to the given tone that satisfies the specified contrast ratio.

The returned value is in the range [0, 100]. Returns -1 if the desired contrast ratio cannot be achieved with the input tone.

tone must be in the range [0, 100]. Invalid values result in -1. ratio should be in the range [1, 21]; invalid values have undefined behavior.

func LighterUnsafe ¶

func LighterUnsafe(tone, ratio float64) float64

LighterUnsafe returns a tone greater than or equal to the given tone that attempts to satisfy the specified contrast ratio.

The returned value is always in the range [0, 100]. Returns 100 if the desired contrast ratio cannot be achieved. Unlike Lighter, this function does not fail but may not always satisfy the desired contrast ratio.

func RatioOfTones ¶

func RatioOfTones(toneA, toneB float64) float64

RatioOfTones returns the contrast ratio between two tones, in the range [1, 21].

toneA and toneB should be values between 0 and 100. Values outside this range will be clamped internally.

func RatioOfYs ¶

func RatioOfYs(y1, y2 float64) float64

RatioOfYs returns the contrast ratio between two relative luminance values.

The ratio is calculated as (lighter + 5) / (darker + 5).