1. An automatic face annotation method, comprising: dividing an input video into different sets of frames; extracting temporal and spatial information by employing camera take and shot boundary detection algorithms on the different sets of frames of the input video; collecting weakly labeled data by crawling weakly labeled face images from social networks; applying face detection together with an iterative refinement clustering algorithm to remove noise of the collected weakly labeled data; generating a labeled database containing refined labeled images as training data; based on the refined labeled images stored in the labeled database, finding and labeling exact frames containing one or more face images in the input video matching any of the refined labeled images in the labeled database; labeling remaining unlabeled face tracks in the input video by a semi-supervised learning algorithm to annotate the face images in the input video; and outputting the input video containing the annotated face images.