Weighted and truncated L1 image smoothing based on unsupervised learning

Edge-preserving image smoothing plays a vital role in the field of computational photography. In this paper, we propose a weighted and truncated L 1 -regularized optimization model for image smoothing. We show that the weighted and truncated scheme significantly promotes the edge-preserving property. Furthermore, we propose a deep unsupervised learning-based filter based on the loss function defined by the proposed optimization model. The proposed filter leverages a U-Net structure, which fully exploits the spatially varying smoothing scales of the edge-preserving filtering. We have conducted extensive experiments to evaluate the proposed filter. The results suggest that our filter outperforms the state-of-the-art filters in image quality on various tasks, such as image smoothing, detail enhancing, HDR tone mapping, and edge detection. Meanwhile, our filter is extremely efficient. It is able to process 720P images in real-time (more than 16 frames per second) on a modern desktop with an Intel i7-8700K CPU, an NVIDIA GTX 1080 GPU and 16GB memory.