Defines projected image system contrast ratio and its measurement. It applies to both permanently installed systems and live events. It applies to front and rear projection. This Standard defines four contrast ratios based on content viewing requirements. System contrast ratio refers to the image as it is presented to viewers in a space with ambient light. Practical metrics to measure and validate the defined contrast ratios are provided. This Standard includes an optional HTML test pattern (appendix), which can be downloaded as a zip file from: http://docdev.infocomm.org/apps/group public/documents.php?view=openforcomment