Rendering Portraitures from Monocular Camera and Beyond

Xiangyu Xu, Deqing Sun, Sifei Liu, Wenqi Ren, Yu-Jin Zhang, Ming-Hsuan Yang, Jian Sun; Proceedings of the European Conference on Computer Vision (ECCV), 2018, pp. 35-50

Shallow Depth-of-Field (DoF) is a desirable effect in photography which renders artistic photos. Usually, it requires single-lens reflex cameras and certain photography skills to generate such effects. Recently, dual-lens on cellphones is used to estimate scene depth and simulate DoF effects for portrait shots. However, this technique cannot be applied to photos already taken and does not work well for whole-body scenes where the subject is at a distance from the cameras. In this work, we introduce an automatic system that achieves portrait DoF rendering for monocular cameras. Specifically, we first exploit Convolutional Neural Networks to estimate the relative depth and portrait segmentation maps from a single input image. Since these initial estimates from a single input are usually coarse and lack fine details, we further learn pixel affinities to refine the coarse estimation maps. With the refined estimation, we conduct depth and segmentation-aware blur rendering to the input image with a Conditional Random Field and image matting. In addition, we train a spatially-variant Recursive Neural Network to learn and accelerate this rendering process. We show that the proposed algorithm can effectively generate portraitures with realistic DoF effects using one single input. Experimental results also demonstrate that our depth and segmentation estimation modules perform favorably against the state-of-the-art methods both quantitatively and qualitatively.