“Unpaired Image-to-Image Translation using Cycle-Consistent Adversarial Networks”の学習報告

The style-based GAN architecture (StyleGAN) yields state-of-the-art results in data-driven unconditional generative image modeling. We expose and analyze several of its characteristic artifacts, and propose changes in both model architecture and training methods to address them. In particular, we redesign the generator normalization, revisit progressive growing, and regularize the generator to encourage good conditioning in the mapping from latent codes to images. In addition to improving image quality, this path length regularizer yields the additional benefit that the generator becomes significantly easier to invert. This makes it possible to reliably attribute a generated image to a particular network. We furthermore visualize how well the generator utilizes its output resolution, and identify a capacity problem, motivating us to train larger models for additional quality improvements. Overall, our improved model redefines the state of the art in unconditional image modeling, both in terms of existing distribution quality metrics as well as perceived image quality.

Analyzing and Improving the Image Quality of StyleGAN

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Uncertainty quantification (UQ) plays a pivotal role in reduction of uncertainties during both optimization and decision making processes. It can be applied to solve a variety of real-world applications in science and engineering. Bayesian approximation and ensemble learning techniques are two most widely-used UQ methods in the literature. In this regard, researchers have proposed different UQ methods and examined their performance in a variety of applications such as computer vision (e.g., self-driving cars and object detection), image processing (e.g., image restoration), medical image analysis (e.g., medical image classification and segmentation), natural language processing (e.g., text classification, social media texts and recidivism risk-scoring), bioinformatics, etc. This study reviews recent advances in UQ methods used in deep learning. Moreover, we also investigate the application of these methods in reinforcement learning (RL). Then, we outline a few important applications of UQ methods. Finally, we briefly highlight the fundamental research challenges faced by UQ methods and discuss the future research directions in this field.

A Review of Uncertainty Quantification in Deep Learning: Techniques, Applications and Challenges

DeepFakes and Beyond: A Survey of Face Manipulation and Fake Detection

Large-scale pre-trained models such as CodeBERT, GraphCodeBERT have earned widespread attention from both academia and industry. Attributed to the superior ability in code representation, they have been further applied in multiple downstream tasks such as clone detection, code search and code translation. However, it is also observed that these state-of-the-art pre-trained models are susceptible to adversarial attacks. The performance of these pre-trained models drops significantly with simple perturbations such as renaming variable names. This weakness may be inherited by their downstream models and thereby amplified at an unprecedented scale. To this end, we propose an approach namely ContraBERT that aims to improve the robustness of pre-trained models via contrastive learning. Specifically, we design nine kinds of simple and complex data augmentation operators on the programming language (PL) and natural language (NL) data to construct different variants. Furthermore, we continue to train the existing pre-trained models by masked language modeling (MLM) and contrastive pre-training task on the original samples with their augmented variants to enhance the robustness of the model. The extensive experiments demonstrate that ContraBERT can effectively improve the robustness of the existing pre-trained models. Further study also confirms that these robustness-enhanced models provide improvements as compared to original models over four popular downstream tasks.

ContraBERT: Enhancing Code Pre-trained Models via Contrastive Learning

Face de-identification (De-ID) removes face identity information in face images to avoid personal privacy leakage. Existing face De-ID breaks the raw identity by cutting out the face regions and recovering the corrupted regions via deep generators, which inevitably affect the generation quality and cannot control generation results according to subsequent intelligent tasks (eg., facial expression recognition). In this work, for the first attempt, we think the face De-ID from the perspective of attribute editing and propose an attribute-aware anonymization network (A3GAN) by formulating face De-ID as a joint task of semantic suppression and controllable attribute injection. Intuitively, the semantic suppression removes the identity-sensitive information in embeddings while the controllable attribute injection automatically edits the raw face along the attributes that benefit De-ID. To this end, we first design a multi-scale semantic suppression network with a novel suppressive convolution unit (SCU), which can remove the face identity along multi-level deep features progressively. Then, we propose an attribute-aware injective network (AINet) that can generate De-ID-sensitive attributes in a controllable way (i.e., specifying which attributes can be changed and which cannot) and inject them into the latent code of the raw face. Moreover, to enable effective training, we design a new anonymization loss to let the injected attributes shift far away from the original ones. We perform comprehensive experiments on four datasets covering four different intelligent tasks including face verification, face detection, facial expression recognition, and fatigue detection, all of which demonstrate the superiority of our face De-ID over state-of-the-art methods.

A3GAN: Attribute-Aware Anonymization Networks for Face De-identification

Deep learning (DL) has been successfully applied to many cutting-edge applications, e.g., image processing, speech recognition, and natural language processing. As more and more DL software is made open-sourced, publicly available, and organized in model repositories and stores (Model Zoo, ModelDepot), there comes a need to understand the relationships of these DL models regarding their maintenance and evolution tasks. Although clone analysis has been extensively studied for traditional software, up to the present, clone analysis has not been investigated for DL software. Since DL software adopts the data-driven development paradigm, it is still not clear whether and to what extent the clone analysis techniques of traditional software could be adapted to DL software. In this paper, we initiate the first step on the clone analysis of DL software at three different levels, i.e., source code level, model structural level, and input/output (I/0)-semantic level, which would be a key in DL software management, maintenance and evolution. We intend to investigate the similarity between these DL models from clone analysis perspective. Several tools and metrics are selected to conduct clone analysis of DL software at three different levels. Our study on two popular datasets (i.e., MNIST and CIFAR-10) and eight DL models of five architectural families (i.e., LeNet, ResNet, DenseNet, AlexNet, and VGG) shows that: 1). the three levels of similarity analysis are generally adequate to find clones between DL models ranging from structural to semantic; 2). different measures for clone analysis used at each level yield similar results; 3) clone analysis of one single level may not render a complete picture of the similarity of DL models. Our findings open up several research opportunities worth further exploration towards better understanding and more effective clone analysis of DL software.

How are Deep Learning Models Similar?: An Empirical Study on Clone Analysis of Deep Learning Software

This paper presents the first model extraction attack against Deep Reinforcement Learning (DRL), which enables an external adversary to precisely recover a black-box DRL model only from its interaction with the environment. Model extraction attacks against supervised Deep Learning models have been widely studied. However, those techniques cannot be applied to the reinforcement learning scenario due to DRL models' high complexity, stochasticity and limited observable information. We propose a novel methodology to overcome the above challenges. The key insight of our approach is that the process of DRL model extraction is equivalent to imitation learning, a well-established solution to learn sequential decision-making policies. Based on this observation, our methodology first builds a classifier to reveal the training algorithm family of the targeted black-box DRL model only based on its predicted actions, and then leverages state-of-the-art imitation learning techniques to replicate the model from the identified algorithm family. Experimental results indicate that our methodology can effectively recover the DRL models with high fidelity and accuracy. We also demonstrate two use cases to show that our model extraction attack can (1) significantly improve the success rate of adversarial attacks, and (2) steal DRL models stealthily even they are protected by DNN watermarks. These pose a severe threat to the intellectual property and privacy protection of DRL applications.

Stealing Deep Reinforcement Learning Models for Fun and Profit

Performance issues of Android apps can tangibly degrade user experience. However, it is challenging for Android developers, especially a novice to develop high-performance apps. It is primarily attributed to the lack of consolidated and abundant programmatic guides for performance optimization. To address this challenge, we propose a data-based approach to obtain performance optimization practices from historical code changes. We first elicit performance-aware Android APIs of which invocations could affect app performance to a large extent, identify historical code changes that produce impact on app performance, and further determine whether they are optimization practices. We have implemented this approach with a tool \tool and evaluated its effectiveness in 2 open source well-maintained projects. The experimental results found 83 changes relevant to performance optimization. Last, we summarize and explain 5 optimization rules to facilitate the development of high-performance apps.

Xiaofei Xie

Papers

ContraBERT: Enhancing Code Pre-trained Models via Contrastive Learning

A3GAN: Attribute-Aware Anonymization Networks for Face De-identification

How are Deep Learning Models Similar?: An Empirical Study on Clone Analysis of Deep Learning Software

Stealing Deep Reinforcement Learning Models for Fun and Profit

Learning Performance Optimization from Code Changes for Android Apps