说明：  通过学习本书，研究人员、工程师能够在3～5个月内，系统了解、掌握人脸检测、人脸识别、人脸检索相关的原理和技术。
(By studying this book, researchers and engineers can systematically understand and master the principles and technologies related to face detection, face recognition and face retrieval within 3-5 months.)