SketchInverter: Multi-Class Sketch-Based Image Generation via GAN Inversion

This paper proposes the first GAN inversion-based method for multi-class sketch-based image generation (MCSBIG). MC-SBIG is a challenging task that requires strong prior knowledge due to the significant domain gap between sketches and natural images. Existing learning-based approaches rely on a large-scale paired dataset to learn the mapping between these two image modalities. However, since the public paired sketch-photo data are scarce, it is struggling for learning-based methods to achieve satisfactory results. In this work, we introduce a new approach based on GAN inversion, which can utilize a powerful pretrained generator to facilitate image generation from a given sketch. Our GAN inversion-based method has two advantages: 1. it can freely take advantage of the prior knowledge of a pretrained image generator; 2. it allows the proposed model to focus on learning the mapping from a sketch to a low-dimension latent code, which is a much easier task than directly mapping to a high-dimension natural image. We also present a novel shape loss to improve generation quality further. Extensive experiments are conducted to show that our method can produce sketch-faithful and photo-realistic images and significantly outperform the baseline methods.