Deep Facial Synthesis: A New Challenge.

The goal of this paper is to conduct a comprehensive study on the facial sketch synthesis (FSS) problem. However, due to the high costs in obtaining hand-drawn sketch datasets, there lacks a complete benchmark for assessing the development of FSS algorithms over the last decade. As such, we first introduce a high-quality dataset for FSS, named FS2K, which consists of 2,104 image-sketch pairs spanning three types of sketch styles, image backgrounds, lighting conditions, skin colors, and facial attributes. FS2K differs from previous FSS datasets in difficulty, diversity, and scalability, and should thus facilitate the progress of FSS research. Second, we present the largest-scale FSS study by investigating 139 classical methods, including 24 handcrafted feature based facial sketch synthesis approaches, 37 general neural-style transfer methods, 43 deep image-to-image translation methods, and 35 image-tosketch approaches. Besides, we elaborate comprehensive experiments for existing 19 cutting-edge models. Third, we present a simple baseline for FSS, named FSGAN. With only two straightforward components, i.e., facial-aware masking and style-vector expansion, FSGAN surpasses the performance of all previous state-of-the-art models on the proposed FS2K dataset, by a large margin. Finally, we conclude with lessons learned over the past years, and point out several unsolved challenges. Our open-source code is available at https://github.com/DengPingFan/FSGAN.