Learning-based methods for single image restoration and translation
Creators: name: Zhang, He
Publisher: name: No Publisher Supplied
Year: 2019

description: In many applications such as drone-based video surveillance, self driving cars and recognition under night-time and low-light conditions, the captured images and videos contain undesirable degradations such as haze, rain, snow, and noise. Furthermore, the performance of many computer vision algorithms often degrades when they are presented with images containing such artifacts. Hence, it is important to develop methods that can automatically remove these artifacts. However, these are dicult problems to solve due to their inherent ill-posed nature. Existing approaches attempt to introduce prior information to convert them into well-posed problems. In this thesis, rather than purely relying on prior-based models, we propose to combine them with data-driven models for image restoration and translation. In particular, we developnew data-driven approaches for 1) single image de-raining, 2) single image dehazing, and 3) thermal-to-visible face synthesis.In the first part of the thesis, we develop three didifferent methods for single image deraining. In the first approach, we develop novel convolutional coding-based methods for single image de-raining, where two different types of filters are learned via convolutional sparse and low-rank coding to characterize the background component and rain-streak component separately. These pre-trained lters are then used to separate the rain component from the image. In the second approach, to ensure that the restored de-rainedresults are indistinguishable from their corresponding clear images, we propose a novel single image de-raining method called Image De-raining Conditional General Adversarial Network (ID-CGAN) which consists of a new rened perceptual loss function and a novel multi-scale discriminator. Finally, to deal with nonuniform rain densities, we present a novel density-aware multi-stream densely connected convolutional neural network-based algorithm that enables the network itself to automatically determine the rain-density information and then efficiently remove the corresponding rain-streaks guided by the estimated rain-density label.In the second part of the thesis, we develop an end-to-end deep learning-based method to address the single image dehazing problem. We propose to combine the physics-based image formation model with data-driven approach for single image dehazing. In particular, a new end-to-end single image dehazing method, called Densely Connected Pyramid Dehazing Network (DCPDN), is proposed which can jointly estimate the transmission map, atmospheric light and dehazed image all together. The end-to-end learning is achieved by directly embedding the atmospheric scattering model into the network, thereby ensuring that the proposed method strictly follows the physical-driven scattering model for dehazing.In the final part of the thesis, we develop an image-to-image translation method for generating high-quality visible images from polarimetric thermal faces. Since polarimetric images contain different  stokes images containing various polarization state information, we propose a Generative Adversarial Network-based multi-stream feature-level fusion technique to synthesize high-quality visible images from polarimetric thermal images. An application of this approach is presented in polarimetric thermal-to-visiblecross-modal face recognition.