A figure of merit called the image clarity index is proposed for quantifying the performance of an optical image stabilizer (OIS) subjected to hand jitter. The image clarity index is defined as the slope angle of the normalized edge spread intensity of a captured image. A two-dimensional map of the index can offer clues as to the design limit on shake angle and frequency. Because of its relative simplicity over the existing metrics such as the modulation transfer function, the proposed index is especially suitable for summary evaluation of OISs and rapid benchmarking of OIS-equipped image sensor modules.