Resolution and Sharpness Requirements for CMS

Abstract

This chapter provides an introduction to the resolution and sharpness requirements for a camera monitor system = CMS (Camera Monitor System) to replace the traditional optical rear-view mirrors. It provides information on how the requirements are translated from what a driver could observe as the minimum angular detail through a mirror to what a driver can expect to observe on a monitor of a CMS. The minimum requirements are derived from the visual acuity of a licensed driver and the magnification of type approved mirrors. Further, this chapter provides guidance on measurement procedure and practical evaluation of a CMS. This chapter is aimed to help the reader to understand the minimum requirements determined by regulation and understand the respective measurement procedure of resolution and sharpness. It clarifies the difference between the units used in definition of the resolution requirements of the CMS and the resolution units used in a standard resolution measurement according to ISO 12233:2014. The evaluation procedure describes a method to verify how many distinguishable line widths are observable within the width in the orientation of interest. It provides a guide to evaluate the system directly on a partially captured image on the CMS monitor, independent of the output image aspect ratio or magnification aspect ratio.