Calculates the difference in visual contrast (ΔΦ*) between two colors in the Lab color space.
The Delta-Phi Star (ΔΦ*) contrast metric is a perceptually-based measure that evaluates
the contrast between two colors based on their lightness values in the Lab color space.
It uses the golden ratio (φ) as an exponent to model human perception of contrast.
Formula: (|L1^φ - L2^φ|)^(1/φ) * √2 - 40
Key characteristics:
Based on the CIE Lab* color space, which is designed to be perceptually uniform
Uses the golden ratio (φ) to model human visual perception
Includes a threshold parameter to ignore imperceptible contrast differences
Returns 0 for contrast values below the perceptual threshold
Accounts for the non-linear response of human vision to lightness differences
Limitations:
Only considers lightness (L*) and ignores chromatic components (a* and b*)
May not accurately predict contrast perception for all viewing conditions
The threshold value is empirically determined and may need adjustment for specific applications
The subtraction of 40 in the formula is a calibration factor that may not be optimal for all scenarios
Calculates the difference in visual contrast (ΔΦ*) between two colors in the Lab color space.
The Delta-Phi Star (ΔΦ*) contrast metric is a perceptually-based measure that evaluates the contrast between two colors based on their lightness values in the Lab color space. It uses the golden ratio (φ) as an exponent to model human perception of contrast.
Formula: (|L1^φ - L2^φ|)^(1/φ) * √2 - 40
Key characteristics:
Limitations: