Robust Face Super-Resolution via Position Relation Model Based on Global Face Context.

Because Face Super-Resolution (FSR) tends to infer High-Resolution (HR) face image by breaking the given Low- Resolution (LR) image into individual patches and inferring the HR correspondence one patch by one separately, Super- Resolution (SR) of face images with serious degradation, especially with occlusion, is still a challenging problem of the computer vision field. To address this problem, we propose a patch-level face model for FSR, which we called the position relation model. This model consists of the mapping relationships in every face position to the rest of the face positions based on similarity. In other words, we build a constraint for each patch position via the relationship in this model from the global range of face. Once an individual input LR image patch is seriously deteriorated, the substitute patch in whole face range can be sought according to the relationship of the model at this position as the provider of the LR information. In this way, the lost facial structures can be compensated by knowledge located in remote pixels or structure information which leads to better high-resolution face images. The LR images with degradations, not only the serious low-quality degradation, e.g. noise, blur, but also the occlusions, can be effectively hallucinated into HR ones. Quantitative and qualitative evaluations on the public datasets demonstrate that the proposed algorithm performs favorably against state-of-theart methods.