Display daylight ambient contrast measurement methods and daylight readability

Two composite metrics to characterize display reflection, contrast, and readability under daylight illumination is proposed. A measurement of the reflection under directed illumination simulating the sun is combined with a measurement of the reflection under uniform diffuse illumination to simulate the sky. The measurements are performed separately in a laboratory, and then the measurement results are combined and scaled to daylight levels with attention to the proper spectra involved for the skylight and sunlight.