luminance will be 220 nits the black state luminance will be 20 5 nits and the contrast ratio will be 10 7 220 20 5 substantially less than the contrast ratio for the display in the darkened room since the extinction ratio of the light valve and therefore the contrast ratio of the lcd in a darkened room are essentially fixed increasing the brightness of the backlight to overcome the effects of ambient light reflections produces limited improvements in the readability of the display reducing the reflection of ambient light from a panel without significantly reducing the brightness or the contrast ratio of the displayed image can significantly improve the readability of lcd displays used in environments with higher intensity ambient lighting ambient light impinging on the front of a screen passes through the transparent layers of the panel and the lcd light is reflected when it crosses the boundary between two materials that have differing indices of refraction for example the high reflectivity of the panel is principally the result of the interaction of ambient light on the proximate surfaces 78 and o 0 of the lcd 50 and the glass 68 glass has a high index of refraction while the air in the gap between the.