Reviewerly/exHarmony huggingface dataset:
WHFL: Wavelet-Domain High Frequency Loss for Sketch-to-Image Translation

Even a rough sketch can effectively convey the descriptions of objects, as humans can imagine the original shape from the sketch. The sketch-to-photo translation is a computer vision task that enables a machine to do this imagination, taking a binary sketch image and generating plausible RGB images corresponding to the sketch. Hence, deep neural networks for this task should learn to generate a wide range of frequencies because most parts of the input (binary sketch image) are composed of DC signals. In this paper, we propose a new loss function named Wavelet-domain High-Frequency Loss (WHFL) to overcome the limitations of previous methods that tend to have a bias toward low frequencies. The proposed method emphasizes the loss on the high frequencies by designing a new weight matrix imposing larger weights on the high bands. Unlike existing handcraft methods that control frequency weights using binary masks, we use the matrix with finely controlled elements according to frequency scales. The WHFL is designed in a multi-scale form, which lets the loss function focus more on the high frequency according to decomposition levels. We use the WHFL as a complementary loss in addition to conventional ones defined in the spatial domain. Experiments show we can improve the qualitative and quantitative results in both spatial and frequency domains. Additionally, we attempt to verify the WHFL’s high-frequency generation capability by defining a new evaluation metric named Unsigned Euclidean Distance Field Error (UEDFE).
A Quality Aware Sample-to-Sample Comparison for Face Recognition

Currently available face datasets mainly consist of a large number of high-quality and a small number of low-quality samples. As a result, a Face Recognition (FR) network fails to learn the distribution of low-quality samples since they are less frequent during training (underrepresented). Moreover, current state-of-the-art FR training paradigms are based on the sample-to-center comparison (i.e., Softmax-based classifier), which results in a lack of uniformity between train and test metrics. This work integrates a quality-aware learning process at the sample level into the classification training paradigm (QAFace). In this regard, Softmax centers are adaptively guided to pay more attention to low-quality samples by using a quality-aware function. Accordingly, QAFace adds a quality-based adjustment to the updating procedure of the Softmax-based classifier to improve the performance on the underrepresented low-quality samples. Our method adaptively finds and assigns more attention to the recognizable low-quality samples in the training datasets. In addition, QAFace ignores the unrecognizable low-quality samples using the feature magnitude as a proxy for quality. As a result, QAFace prevents class centers from getting distracted from the optimal direction. The proposed method is superior to the state-of-the-art algorithms in extensive experimental results on the CFP-FP, LFW, CPLFW, CALFW, AgeDB, IJB-B, and IJB-C datasets.
Generative Alignment of Posterior Probabilities for Source-free Domain Adaptation

Existing domain adaptation literature comprises multiple techniques that align the labeled source and unlabeled target domains at different stages, and predict the target labels. In a source-free domain adaptation setting, the source data is not available for alignment. We present a source-free generative paradigm that captures the relations between the source categories and enforces them onto the unlabeled target data, thereby circumventing the need for source data without introducing any new hyper-parameters. The adaptation is performed through the adversarial alignment of the posterior probabilities of the source and target categories. The proposed approach demonstrates competitive performance against other source-free domain adaptation techniques and can also be used for source-present settings.
Semantics Guided Contrastive Learning of Transformers for Zero-shot Temporal Activity Detection

Zero-shot temporal activity detection (ZSTAD) is the problem of simultaneous temporal localization and classification of activity segments that are previously unseen during training. This is achieved by transferring the knowledge learned from semantically-related seen activities. This ability to reason about unseen concepts without supervision makes ZSTAD very promising for applications where the acquisition of annotated training videos is difficult. In this paper, we design a transformer-based framework titled TranZAD, which streamlines the detection of unseen activities by casting ZSTAD as a direct set-prediction problem, removing the need for hand-crafted designs and manual post-processing. We show how a semantic information-guided contrastive learning strategy can effectively train TranZAD for the zero-shot setting, enabling the efficient transfer of knowledge from the seen to the unseen activities. To reduce confusion between unseen activities and unrelated background information in videos, we introduce a more efficient method of computing the background class embedding by dynamically adapting it as part of the end-to-end learning. Additionally, unlike existing work on ZSTAD, we do not assume the knowledge of which classes are unseen during training and use the visual and semantic information of only the seen classes for the knowledge transfer. This makes TranZAD more viable for practical scenarios, which we evaluate by conducting extensive experiments on Thumos’14 and Charades.
Task Agnostic and Post-hoc Unseen Distribution Detection

Despite the recent advances in out-of-distribution(OOD) detection, anomaly detection, and uncertainty estimation tasks, there do not exist a task-agnostic and post-hoc approach. To address this limitation, we design a novel clustering-based ensembling method, called Task Agnostic and Post-hoc Unseen Distribution Detection (TAPUDD) that utilizes the features extracted from the model trained on a specific task. Explicitly, it comprises of TAP-Mahalanobis, which clusters the training datasets’ features and determines the minimum Mahalanobis distance of the test sample from all clusters. Further, we propose the Ensembling module that aggregates the computation of iterative TAP-Mahalanobis for a different number of clusters to provide reliable and efficient cluster computation. Through extensive experiments on synthetic and real-world datasets, we observe that our task-agnostic approach can detect unseen samples effectively across diverse tasks and performs better or on-par with the existing task-specific baselines. We also demonstrate that our method is more viable even for large-scale classification tasks.
GLAD: A Global-to-Local Anomaly Detector

Learning to detect automatic anomalies in production plants remains a machine learning challenge. Since anomalies by definition cannot be learned, their detection must rely on a very accurate "normality model". To this aim, we introduce here a global-to-local Gaussian model for neural network features, learned from a set of normal images. This probabilistic model enables unsupervised anomaly detection. A global Gaussian mixture model of the features is first learned using all available features from normal data. This global Gaussian mixture model is then localized by an adaptation of the K-MLE algorithm, which learns a spatial weight map for each Gaussian. These weights are then used instead of the mixture weights to detect anomalies. This method enables precise modeling of complex data, even with limited data. Applied on WideResnet50-2 features, our approach outperforms the previous state of the art on the MVTec dataset, particularly on the object category. It is robust to perturbations that are frequent in production lines, such as imperfect alignment, and is on par in terms of memory and computation time with the previous state of the art.
Leveraging Off-the-shelf Diffusion Model for Multi-attribute Fashion Image Manipulation

Fashion attribute editing is a task that aims to convert the semantic attributes of a given fashion image while preserving the irrelevant regions. Previous works typically employ conditional GANs where the generator explicitly learns the target attributes and directly execute the conversion. These approaches, however, are neither scalable nor generic as they operate only with few limited attributes and a separate generator is required for each dataset or attribute set. Inspired by the recent advancement of diffusion models, we explore the classifier-guided diffusion that leverages the off-the-shelf diffusion model pretrained on general visual semantics such as Imagenet. In order to achieve a generic editing pipeline, we pose this as multi-attribute image manipulation task, where the attribute ranges from item category, fabric, pattern to collar and neckline. We empirically show that conventional methods fail in our challenging setting, and study efficient adaptation scheme that involves recently introduced attention-pooling technique to obtain a multi-attribute classifier guidance. Based on this, we present a mask-free fashion attribute editing framework that leverages the classifier logits and the cross-attention map for manipulation. We empirically demonstrate that our framework achieves convincing sample quality and attribute alignments.
HandGCNFormer: A Novel Topology-Aware Transformer Network for 3D Hand Pose Estimation

Despite the substantial progress in 3D hand pose estimation, inferring plausible and accurate poses in the presence of severe self-occlusion and high self-similarity remains an inherent challenge. To mitigate the ambiguity arising from invisible and similar joints, we propose a novel Topology-aware Transformer network named HandGCNFormer, incorporating the prior knowledge of hand kinematic topology into the network while modeling long-range context information. Specifically, we present a novel Graphformer decoder with an additional node-offset graph convolutional layer (NoffGConv) that optimizes the synergy of Transformer and GCN, capturing long-range dependencies as well as local topology connection between joints. Furthermore, we replace the standard MLP prediction head with a novel Topology-aware head to better utilize local topology constraints for more plausible and accurate poses. Our method achieves state-of-the-art performance on four challenging datasets including Hands2017, NYU, ICVL, and MSRA.
Feature Disentanglement Learning with Switching and Aggregation for Video-based Person Re-Identification

In video person re-identification (Re-ID), the network must consistently extract features of the target person from successive frames. Existing methods tend to focus only on how to use temporal information, which often leads to networks being fooled by similar appearances and same backgrounds. In this paper, we propose a Disentanglement and Switching and Aggregation Network (DSANet), which segregates the features representing identity and features based on camera characteristics, and pays more attention to ID information. We also introduce an auxiliary task that utilizes a new pair of features created through switching and aggregation to increase the network’s capability for various camera scenarios. Furthermore, we devise a Target Localization Module (TLM) that extracts robust features against a change in the position of the target according to the frame flow and a Frame Weight Generation (FWG) that reflects temporal information in the final representation. Various loss functions for disentanglement learning are designed so that each component of the network can cooperate while satisfactorily performing its own role. Quantitative and qualitative results from extensive experiments demonstrate the superiority of DSANet over state-of-the-art methods on three benchmark datasets.
Relaxing Contrastiveness in Multimodal Representation Learning

Multimodal representation learning for images with paired raw texts can improve the usability and generality of the learned semantic concepts while significantly reducing annotation costs. In this paper, we explore the design space of loss functions in visual-linguistic pretraining frameworks and propose a novel Relaxed Contrastive (ReCo) objective, which act as a drop-in replacement of the widely used InfoNCE loss. The key insight of ReCo is to allow a relaxed negative space by not penalizing unpaired multimodal samples (i.e., negative pairs) that are already orthogonal or negatively correlated. Unlike the widely-used InfoNCE, which keeps repelling negative pairs as long as they are not anti-correlated, ReCo by design embraces more diversity and flexibility of the learned embeddings. We conduct exten-sive experiments using ReCo with state-of-the-art models by pretraining on the MIMIC-CXR dataset that consists of chest radiographs and free-text radiology reports, and eval-uating on the CheXpert dataset for multimodal retrieval and disease classification. Our ReCo achieves an absolute improvement of 2.9% over the InfoNCE baseline on the CheXpert Retrieval dataset in average retrieval precision and re-ports better or comparable performance in the linear evaluation and finetuning for classification. We further show that ReCo outperforms InfoNCE on the Flickr30K dataset by 1.7% in retrieval Recall@1, demonstrating the generalizability of our approach to natural images.
Expansion of Visual Hints for Improved Generalization in Stereo Matching

We introduce visual hints expansion for guiding stereo matching to improve generalization. Our work is motivated by the robustness of Visual Inertial Odometry (VIO) in computer vision and robotics, where a sparse and unevenly distributed set of feature points characterizes a scene. To improve stereo matching, we propose to elevate 2D hints to 3D points. These sparse and unevenly distributed 3D visual hints are expanded using a 3D random geometric graph, which enhances the learning and inference process. We evaluate our proposal on multiple widely adopted benchmarks and show improved performance without access to additional sensors other than the image sequence. To highlight practical applicability and symbiosis with visual odometry, we demonstrate how our methods run on embedded hardware.
Human-in-the-Loop Video Semantic Segmentation Auto-Annotation

Accurate per-pixel semantic class annotations of the entire video are crucial for designing and evaluating video semantic segmentation algorithms. However, the annotations are usually limited to a small subset of the video frames due to the high annotation cost and limited budget in practice. In this paper, we propose a novel human-in-the-loop framework called HVSA to generate semantic segmentation annotations for the entire video using only a small annotation budget. Our method alternates between active sample selection and test-time fine-tuning algorithms until annotation quality is satisfied. In particular, the active sample selection algorithm picks the most important samples to get manual annotations, where the sample can be a video frame, a rectangle, or even a super-pixel. Further, the test-time fine-tuning algorithm propagates the manual annotations of selected samples to the entire video. Real-world experiments show that our method generates highly accurate and consistent semantic segmentation annotations while simultaneously enjoys significantly small annotation cost.
Language-free Training for Zero-shot Video Grounding

Given an untrimmed video and a language query depicting a specific temporal moment in the video, video grounding aims to localize the time interval by understanding the text and video simultaneously. One of the most challenging issues is an extremely time- and cost-consuming annotation collection, including video captions in a natural language form and their corresponding temporal regions. In this paper, we present a simple yet novel training framework for video grounding in the zero-shot setting, which learns a network with only video data without any annotation. Inspired by the recent language-free paradigm, i.e. training without language data, we train the network without compelling the generation of fake (pseudo) text queries into a natural language form. Specifically, we propose a method for learning a video grounding model by selecting a temporal interval as a hypothetical correct answer and considering the visual feature selected by our method in the interval as a language feature, with the help of the well-aligned visual-language space of CLIP. Extensive experiments demonstrate the prominence of our language-free training framework, outperforming the existing zero-shot video grounding method and even several weakly-supervised approaches with large margins on two standard datasets.
Proactive Deepfake Defence via Identity Watermarking

The explosive progress of Deepfake techniques poses unprecedented privacy and security risks to our society by creating real-looking but fake visual content. The current Deepfake detection studies are still in their infancy because they mainly rely on capturing artifacts left by a Deepfake synthesis process as detection clues, which can be easily removed by various distortions (e.g. blurring) or advanced Deepfake techniques. In this paper, we propose a novel method that does not depend on identifying the artifacts but resorts to the mechanism of anti-counterfeit labels to protect face images from malicious Deepfake tampering. Specifically, we design a neural network with an encoder-decoder structure to embed watermarks as anti-Deepfake labels into the facial identity features. The injected label is entangled with the facial identity feature, so it will be sensitive to face swap translations (i.e., Deepfake) and robust to conventional image modifications (e.g., resize and compress). Therefore, we can identify whether watermarked images have been tampered with by Deepfake methods according to the label’s existence. Experimental results demonstrate that our method can achieve average detection accuracy of more than 80%, which validates the proposed method’s effectiveness in implementing Deepfake detection.
Difficulty-Net: Learning to Predict Difficulty for Long-Tailed Recognition

Long-tailed datasets, where head classes comprise much more training samples than tail classes, cause recognition models to get biased towards the head classes. Weighted loss is one of the most popular ways of mitigating this issue, and a recent work has suggested that class-difficulty might be a better clue than conventionally used class-frequency to decide the distribution of weights. A heuristic formulation was used in the previous work for quantifying the difficulty, but we empirically find that the optimal formulation varies depending on the characteristics of datasets. Therefore, we propose Difficulty-Net, which learns to predict the difficulty of classes using the model’s performance in a meta-learning framework. To make it learn reasonable difficulty of a class within the context of other classes, we newly introduce two key concepts, namely the relative difficulty and the driver loss. The former helps Difficulty-Net take other classes into account when calculating difficulty of a class, while the latter is indispensable for guiding the learning to a meaningful direction. Extensive experiments on popular long-tailed datasets demonstrated the effectiveness of the proposed method, and it achieved state-of-the-art performance on multiple long-tailed datasets. Code is available at https://github.com/hitachi-rd-cv/Difficulty_Net.
NAPReg: Nouns As Proxies Regularization for Semantically Aware Cross-Modal Embeddings

Cross-modal retrieval is a fundamental vision-language task with a broad range of practical applications. Text-to-image matching is the most common form of cross-modal retrieval where, given a large database of images and a textual query, the task is to retrieve the most relevant set of images. Existing methods utilize dual encoders with an attention mechanism and a ranking loss for learning embeddings that can be used for retrieval based on cosine similarity. Despite the fact that these methods attempt to perform semantic alignment across visual regions and textual words using tailored attention mechanisms, there is no explicit supervision from the training objective to enforce such alignment. To address this, we propose NAPReg, a novel regularization formulation that projects high-level semantic entities i.e Nouns into the embedding space as shared learnable proxies. We show that using such a formulation allows the attention mechanism to learn better word-region alignment while also utilizing region information from other samples to build a more generalized latent representation for semantic concepts. Experiments on three benchmark datasets i.e. MS-COCO, Flickr30k and Flickr8k demonstrate that our method achieves state-of-the-art results in cross-modal metric learning for text-image and image-text retrieval tasks. Code: https://github.com/bhavinjawade/NAPReq
MonoEdge: Monocular 3D Object Detection Using Local Perspectives

We propose a novel approach for monocular 3D object detection by leveraging local perspective effects of each object. While the global perspective effect shown as size and position variations has been exploited for monocular 3D detection extensively, the local perspectives has long been overlooked. We design a local perspective module to regress a newly defined variable named keyedge-ratios as the parameterization of the local shape distortion to account for the local perspective, and derive the object depth and yaw angle from it. Theoretically, this module does not rely on the pixel-wise size or position in the image of the objects, therefore independent of the camera intrinsic parameters. By plugging this module in existing monocular 3D object detection frameworks, we incorporate the local perspective distortion with global perspective effect for monocular 3D reasoning, and we demonstrate the effectiveness and superior performance over strong baseline methods in multiple datasets.
Resolving Class Imbalance for LiDAR-based Object Detector by Dynamic Weight Average and Contextual Ground Truth Sampling

An autonomous driving system requires a 3D object detector, which must perceive all present road agents reliably to navigate an environment safely. However, real-world driving datasets often suffer from the problem of data imbalance, which causes difficulties in training a model that works well across all classes, resulting in an undesired imbalanced sub-optimal performance. In this work, we propose a method to address this data imbalance problem. Our method consists of two main components: (i) a LiDAR-based 3D object detector with per-class multiple detection heads where losses from each head are modified by dynamic weight average to be balanced. (ii) Contextual ground truth (GT) sampling, where we improve conventional GT sampling techniques by leveraging semantic information to augment point cloud with sampled ground truth GT objects. Our experiment with KITTI and nuScenes datasets confirms our proposed method’s effectiveness in dealing with the data imbalance problem, producing better detection accuracy compared to existing approaches.