Performance metrics for auto-focus in digital and cell-phone cameras

Passive auto-focus (AF) is a key component of many digital and cell-phone camera systems. In order to make informed choices in the selection of a passive AF search algorithm, it is essential to have performance metrics. The performance metrics currently utilized do not take into consideration all aspects of auto-focusing. In this paper, four performance metrics which measure all relevant aspects of an AF system is considered at the same time. These metrics include focusing speed, accuracy, power consumption and user experience. Experimental results on a prototype digital camera platform are presented to compare the AF performance of four popular AF search algorithms exhibiting the usefulness of the introduced set of AF performance metrics.