Example-Based Composite Sketching of Human Portraits
Author(s): Hong Chen, Ziqiang Liu, Chuck Rose, Ying-Qing Xu, Heung-Yeung Shum, David H. Salesin.
Proceedings: 3rd International Symposium on Non-Photorealistic Animation and Rendering (NPAR'04),
2004.
[BibTeX] 
Abstract:
Creating a portrait in the style of a particular artistic tradition or a
particular artist is a difficult problem. Elusive to codify algorithmically,
the nebulous qualities which combine to form artwork are
often well captured using example-based approaches. These methods
place the artist in the process, often during system training, in
the hope that their talents may be tapped.
Example based methods do not make this problem easy, however.
Examples are precious, so training sets are small, reducing
the number of techniques which may be employed. We propose a
system which combines two separate but similar subsystems, one
for the face and another for the hair, each of which employs a
global and a local model. Facial exaggeration to achieve the desired
stylistic look is handled during the global face phase. Each subsystem
uses a divide-and-conquer approach, but while the face subsystem
decomposes into separable subproblems for the eyes, mouth,
nose, etc., the hair needs to be subdivided in a relatively arbitrary
way, making the hair subproblem decomposition an important step
which must be handled carefully with a structured model and a detailed
model.