84 research outputs found
Deep Reinforcement Learning based Patch Selection for Illuminant Estimation
Previous deep learning based approaches to illuminant estimation either resized the raw image to lower resolution or randomly cropped image patches for the deep learning model. However, such practices would inevitably lead to information loss or the selection of noisy patches that would affect estimation accuracy. In this paper, we regard patch selection in neural network based illuminant estimation as a controlling problem of selecting image patches that could help remove noisy patches and improve estimation accuracy. To achieve this, we construct a selection network (SeNet) to learn a patch selection policy. Based on data statistics and the learning progression state of the deep illuminant estimation network (DeNet), the SeNet decides which training patches should be input to the DeNet, which in turn gives feedback to the SeNet for it to update its selection policy. To achieve such interactive and intelligent learning, we utilize a reinforcement learning approach termed policy gradient to optimize the SeNet. We show that the proposed learning strategy can enhance the illuminant estimation accuracy, speed up the convergence and improve the stability of the training process of DeNet. We evaluate our method on two public datasets and demonstrate our method outperforms state-of-the-art approaches
HDRfeat: A Feature-Rich Network for High Dynamic Range Image Reconstruction
A major challenge for high dynamic range (HDR) image reconstruction from
multi-exposed low dynamic range (LDR) images, especially with dynamic scenes,
is the extraction and merging of relevant contextual features in order to
suppress any ghosting and blurring artifacts from moving objects. To tackle
this, in this work we propose a novel network for HDR reconstruction with deep
and rich feature extraction layers, including residual attention blocks with
sequential channel and spatial attention. For the compression of the
rich-features to the HDR domain, a residual feature distillation block (RFDB)
based architecture is adopted. In contrast to earlier deep-learning methods for
HDR, the above contributions shift focus from merging/compression to feature
extraction, the added value of which we demonstrate with ablation experiments.
We present qualitative and quantitative comparisons on a public benchmark
dataset, showing that our proposed method outperforms the state-of-the-art.Comment: 4 pages, 5 figure
ContraBERT: Enhancing Code Pre-trained Models via Contrastive Learning
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
Enhancing Security Patch Identification by Capturing Structures in Commits
With the rapid increasing number of open source software (OSS), the majority
of the software vulnerabilities in the open source components are fixed
silently, which leads to the deployed software that integrated them being
unable to get a timely update. Hence, it is critical to design a security patch
identification system to ensure the security of the utilized software. However,
most of the existing works for security patch identification just consider the
changed code and the commit message of a commit as a flat sequence of tokens
with simple neural networks to learn its semantics, while the structure
information is ignored. To address these limitations, in this paper, we propose
our well-designed approach E-SPI, which extracts the structure information
hidden in a commit for effective identification. Specifically, it consists of
the code change encoder to extract the syntactic of the changed code with the
BiLSTM to learn the code representation and the message encoder to construct
the dependency graph for the commit message with the graph neural network (GNN)
to learn the message representation. We further enhance the code change encoder
by embedding contextual information related to the changed code. To demonstrate
the effectiveness of our approach, we conduct the extensive experiments against
six state-of-the-art approaches on the existing dataset and from the real
deployment environment. The experimental results confirm that our approach can
significantly outperform current state-of-the-art baselines
Visual quality assessment for super-resolved images: database and method
Image super-resolution (SR) has been an active re-search problem which has recently received renewed interest due to the introduction of new technologies such as deep learning. However, the lack of suitable criteria to evaluate the SR perfor-mance has hindered technology development. In this paper, we fill a gap in the literature by providing the first publicly available database as well as a new image quality assessment (IQA) method specifically designed for assessing the visual quality of su-per-resolved images (SRIs). In constructing the Quality Assess-ment Database for SRIs (QADS), we carefully selected 20 refer-ence images and created 980 SRIs using 21 image SR methods. Mean opinion score (MOS) for these SRIs are collected through 100 individuals participating a suitably designed psychovisual experiment. Extensive numerical and statistical analysis is per-formed to show that the MOS of QADS has excellent suitability and reliability. The psychovisual experiment has led to the dis-covery that, unlike distortions encountered in other IQA data-bases, artifacts of the SRIs degenerate the image structure as well as image texture. Moreover, the structural and textural degener-ations have distinctive perceptual properties. Based on these in-sights, we propose a novel method to assess the visual quality of SRIs by separately considering the structural and textural com-ponents of images. Observing that textural degenerations are mainly attributed to dissimilar texture or checkerboard artifacts, we propose to measure the changes of textural distributions. We also observe that structural degenerations appear as blurring and jaggies artifacts in SRIs and develop separate similarity measures for different types of structural degenerations. A new pooling mechanism is then used to fuse the different similarities together to give the final quality score for an SRI. Experiments conducted on the QADS demonstrate that our method significantly outper-forms classical as well as current state-of-the-art IQA methods
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