1. Introduction
Face age progression (i.e., prediction of future looks) and regression (i.e., estimation of previous looks), also referred to as face aging and rejuvenation, aims to render face images with or without the “aging” effect but still preserve personalized features of the face (i.e., personality). It has tremendous impact to a wide-range of applications, e.g., face prediction of wanted/missing person, age-invariant verification, entertainment, etc. The area has been attracting a lot of research interests despite the extreme challenge in the problem itself. Most of the challenges come from the rigid requirement to the training and testing datasets, as well as the large variation presented in the face image in terms of expression, pose, resolution, illumination, and occlusion. The rigid requirement on the dataset refers to the fact that most existing works require the availability of paired samples, i.e., face images of the same person at different ages, and some even require paired samples over a long range of age span, which is very difficult to collect. For example, the largest aging dataset “Morph” [12] only captured images with an average time span of 164 days for each individual. In addition, existing works also require the query image to be labeled with the true age, which can be inconvenient from time to time. Given the training data, existing works normally divide them into different age groups and learn a transformation between the groups, therefore, the query image has to be labeled in order to correctly position the image.
We assume the face images lie on a manifold , and images are clustered according to their ages and personality by a different direction. Given a query image, it will first projected to the manifold, and then after the smooth transformation on the manifold, the corresponding images will be projected back with aging patterns.