1. A method, comprising: receiving a facial image; creating a line-drawing from the facial image; computing a set of semantic facial features from key points of a face in the facial image to describe a geometric shape of the face; comparing relationships among the semantic facial features to corresponding relationships between unexaggerated and exaggerated features in reference facial images and associated reference caricatures drawn by an artist and stored in a reference database; applying a kernel regression to select some of the semantic facial features in the facial image for caricature exaggeration and to exaggerate the semantic facial features into exaggerated features, wherein a nonlinear mapping between corresponding unexaggerated and exaggerated features in the reference database is learned via the kernel regression; selecting a relationship among facial features of the facial image to exaggerate based on a variance of the relationship from a norm derived from the reference facial images in the reference database, wherein relationships having relatively high variance from the norm are selected for exaggeration, wherein the selecting a relationship comprises: performing a kernel regression in order to map the relationship to similar relationships among similar facial features in the reference facial images; assigning weights to the reference facial images based on a similarity of the relationship to corresponding relationships among facial features in the facial images, wherein a high weight is assigned to a high similarity; and applying a linear regression to the weighted facial images generating from the facial image, an exaggerated face shape by applying a maximum likelihood estimation (MLE) to the exaggerated features of the facial image; and morphing the line-drawing into the exaggerated face shape to create a facial caricature, wherein: for each semantic facial feature to be exaggerated a degree of exaggeration is determined by the kernel regression; and the degree of exaggeration of each feature to be exaggerated is adjustable by a user.