GenAI4ELab/papercli-papers huggingface dataset:
TIAM - A Metric for Evaluating Alignment in Text-to-Image Generation
Authors: Paul Grimal; Hervé Le Borgne; Olivier Ferret; Julien Tourille
Venue: WACV 2024 (main)

Abstract: The progress in the generation of synthetic images has made it crucial to assess their quality. While several metrics have been proposed to assess the rendering of images, it is crucial for Text-to-Image (T2I) models, which generate images based on a prompt, to consider additional aspects such as to which extent the generated image matches the important content of the prompt. Moreover, although the generated images usually result from a random starting point, the influence of this one is generally not considered. In this article, we propose a new metric based on prompt templates to study the alignment between the content specified in the prompt and the corresponding generated images. It allows us to better characterize the alignment in terms of the type of the specified objects, their number, and their color. We conducted a study on several recent T2I models about various aspects. An additional interesting result we obtained with our approach is that image quality can vary drastically depending on the noise used as a seed for the images. We also quantify the influence of the number of concepts in the prompt, their order as well as their (color) attributes. Finally, our method allows us to identify some seeds that produce better images than others, opening novel directions of research on this understudied topic.
HDMNet: A Hierarchical Matching Network With Double Attention for Large-Scale Outdoor LiDAR Point Cloud Registration
Authors: Weiyi Xue; Fan Lu; Guang Chen
Venue: WACV 2024 (main)

Abstract: Outdoor LiDAR point clouds are typically large-scale and complexly distributed. To achieve efficient and accurate registration, emphasizing the similarity among local regions and prioritizing global local-to-local matching is of utmost importance, subsequent to which accuracy can be enhanced through cost-effective fine registration. In this paper, a novel hierarchical neural network with double attention named HDMNet is proposed for large-scale outdoor LiDAR point cloud registration. Specifically, A novel feature consistency enhanced double-soft matching network is introduced to achieve two-stage matching with high flexibility while enlarging the receptive field with high efficiency in a patch-to-patch manner, which significantly improves the registration performance. Moreover, in order to further utilize the sparse matching information from deeper layer, we develop a novel trainable embedding mask to incorporate the confidence scores of correspondences obtained from pose estimation of deeper layer, eliminating additional computations. The high-confidence keypoints in the sparser point cloud of the deeper layer correspond to a high-confidence spatial neighborhood region in shallower layer, which will receive more attention, while the features of non-key regions will be masked. Extensive experiments are conducted on two large-scale outdoor LiDAR point cloud datasets to demonstrate the high accuracy and efficiency of the proposed HDMNet.
UGPNet: Universal Generative Prior for Image Restoration
Authors: Hwayoon Lee; Kyoungkook Kang; Hyeongmin Lee; Seung-Hwan Baek; Sunghyun Cho
Venue: WACV 2024 (main)

Abstract: Recent image restoration methods can be broadly categorized into two classes: (1) regression methods that recover the rough structure of the original image without synthesizing high-frequency details and (2) generative methods that synthesize perceptually-realistic high-frequency details even though the resulting image deviates from the original structure of the input. While both directions have been extensively studied in isolation, merging their benefits with a single framework has been rarely studied. In this paper, we propose UGPNet, a universal image restoration framework that can effectively achieve the benefits of both approaches by simply adopting a pair of an existing regression model and a generative model. UGPNet first restores the image structure of a degraded input using a regression model and synthesizes a perceptually-realistic image with a generative model on top of the regressed output. UGPNet then combines the regressed output and the synthesized output, resulting in a final result that faithfully reconstructs the structure of the original image in addition to perceptually-realistic textures. Our extensive experiments on deblurring, denoising, and super-resolution demonstrate that UGPNet can successfully exploit both regression and generative methods for high-fidelity image restoration.
Defense Against Adversarial Cloud Attack on Remote Sensing Salient Object Detection
Authors: Huiming Sun; Lan Fu; Jinlong Li; Qing Guo; Zibo Meng; Tianyun Zhang; Yuewei Lin; Hongkai Yu
Venue: WACV 2024 (main)

Abstract: Detecting the salient objects in a remote sensing image has wide applications. Many existing deep learning methods have been proposed for Salient Object Detection (SOD) in remote sensing images with remarkable results. However, the recent adversarial attack examples, generated by changing a few pixel values on the original image, could result in a collapse for the well-trained deep learning model. Different with existing methods adding perturbation to original images, we propose to jointly tune adversarial exposure and additive perturbation for attack and constrain image close to cloudy image as Adversarial Cloud. Cloud is natural and common in remote sensing images, however, camouflaging cloud based adversarial attack and defense for remote sensing images are not well studied before. Furthermore, we design DefenseNet as a learnable pre-processing to the adversarial cloudy images to preserve the performance of the deep learning based remote sensing SOD model, without tuning the already deployed deep SOD model. By considering both regular and generalized adversarial examples, the proposed DefenseNet can defend the proposed Adversarial Cloud in white-box setting and other attack methods in black-box setting. Experimental results on a synthesized benchmark from the public remote sensing dataset (EORSSD) show the promising defense against adversarial cloud attacks.
Diffusion in the Dark: A Diffusion Model for Low-Light Text Recognition
Authors: Cindy M. Nguyen; Eric R. Chan; Alexander W. Bergman; Gordon Wetzstein
Venue: WACV 2024 (main)

Abstract: Capturing images is a key part of automation for high-level tasks such as scene text recognition. Low-light conditions pose a challenge for high-level perception stacks, which are often optimized on well-lit, artifact-free images. Reconstruction methods for low-light images can produce well-lit counterparts, but typically at the cost of high-frequency details critical for downstream tasks. We propose Diffusion in the Dark (DiD), a diffusion model for low-light image reconstruction for text recognition. DiD provides qualitatively competitive reconstructions with that of state-of-the-art (SOTA), while preserving high-frequency details even in extremely noisy, dark conditions. We demonstrate that DiD, without any task-specific optimization, can outperform SOTA low-light methods in low-light text recognition on real images, bolstering the potential of diffusion models to solve ill-posed inverse problems.
RobustCLEVR: A Benchmark and Framework for Evaluating Robustness in Object-Centric Learning
Authors: Nathan Drenkow; Mathias Unberath
Venue: WACV 2024 (main)

Abstract: Object-centric representation learning offers the potential to overcome limitations of image-level representations by explicitly parsing image scenes into their constituent components. While image-level representations typically lack robustness to natural image corruptions, the robustness of object-centric methods remains largely untested. To address this gap, we present the RobustCLEVR benchmark dataset and evaluation framework. Our framework takes a novel approach to evaluating robustness by enabling the specification of causal dependencies in the image generation process grounded in expert knowledge and capable of producing a wide range of image corruptions unattainable in existing robustness evaluations. Using our framework, we define several causal models of the image corruption process which explicitly encode assumptions about the causal relationships and distributions of each corruption type. We generate dataset variants for each causal model on which we evaluate state-of-the-art object-centric methods. Overall, we find that object-centric methods are not inherently robust to image corruptions. Our causal evaluation approach exposes model sensitivities not observed using conventional evaluation processes, yielding greater insight into robustness differences across algorithms. Lastly, while conventional robustness evaluations view corruptions as out-of-distribution, we use our causal framework to show that even training on in-distribution image corruptions does not guarantee increased model robustness. This work provides a step towards more concrete and substantiated understanding of model performance and deterioration under complex corruption processes of the real-world.
AFTer-SAM: Adapting SAM With Axial Fusion Transformer for Medical Imaging Segmentation
Authors: Xiangyi Yan; Shanlin Sun; Kun Han; Thanh-Tung Le; Haoyu Ma; Chenyu You; Xiaohui Xie
Venue: WACV 2024 (main)

Abstract: The Segmentation Anything Model (SAM) has demonstrated effectiveness in various segmentation tasks. However, its application to 3D medical data has posed challenges due to its inherent design for both 2D and natural images. While there have been attempts to apply SAM to medical images on a slice-by-slice basis, the outcomes have been less than optimal. In this study, we introduce AFTer-SAM, an adaptation of SAM designed for volumetric medical image segmentation. By incorporating an Axial Fusion Transformer, AFTer-SAM is capable of capturing both intra-slice details and inter-slice contextual information, essential for accurate medical image segmentation. Given the potential computational challenges of training this enhanced model, we utilize Low-Rank Adaptation (LoRA) to efficiently fine-tune the weights of the Axial Fusion Transformer. This ensures a streamlined training process without compromising on performance. Our results indicate that AFTer-SAM offers significant improvements in volumetric medical image segmentation, suggesting a promising direction for the application of large pre-trained models in medical imaging.
Plasticity-Optimized Complementary Networks for Unsupervised Continual Learning
Authors: Alex Gomez-Villa; Bartlomiej Twardowski; Kai Wang; Joost van de Weijer
Venue: WACV 2024 (main)

Abstract: Continuous unsupervised representation learning (CURL) research has greatly benefited from improvements in self-supervised learning (SSL) techniques. As a result, existing CURL methods using SSL can learn high-quality representations without any labels, but with a notable performance drop when learning on a many-tasks data stream. We hypothesize that this is caused by the regularization losses that are imposed to prevent forgetting, leading to a suboptimal plasticity-stability trade-off: they either do not adapt fully to the incoming data (low plasticity), or incur significant forgetting when allowed to fully adapt to a new SSL pretext-task (low stability). In this work, we propose to train an expert network that is relieved of the duty of keeping the previous knowledge and can focus on performing optimally on the new tasks (optimizing plasticity). In the second phase, we combine this new knowledge with the previous network in an adaptation-retrospection phase to avoid forgetting and initialize a new expert with the knowledge of the old network. We perform several experiments showing that our proposed approach outperforms other CURL exemplar-free methods in few- and many-task split settings. Furthermore, we show how to adapt our approach to semi-supervised continual learning (Semi-SCL) and show that we surpass the accuracy of other exemplar-free Semi-SCL methods and reach the results of some others that use exemplars.
FATE: Feature-Agnostic Transformer-Based Encoder for Learning Generalized Embedding Spaces in Flow Cytometry Data
Authors: Lisa Weijler; Florian Kowarsch; Michael Reiter; Pedro Hermosilla; Margarita Maurer-Granofszky; Michael Dworzak
Venue: WACV 2024 (main)

Abstract: While model architectures and training strategies have become more generic and flexible with respect to different data modalities over the past years, a persistent limitation lies in the assumption of fixed quantities and arrangements of input features. This limitation becomes particularly relevant in scenarios where the attributes captured during data acquisition vary across different samples. In this work, we aim at effectively leveraging data with varying features, without the need to constrain the input space to the intersection of potential feature sets or to expand it to their union. We propose a novel architecture that can directly process data without the necessity of aligned feature modalities by learning a general embedding space that captures the relationship between features across data samples with varying sets of features. This is achieved via a set-transformer architecture augmented by feature-encoder layers, thereby enabling the learning of a shared latent feature space from data originating from heterogeneous feature spaces. The advantages of the model are demonstrated for automatic cancer cell detection in acute myeloid leukemia in flow cytometry data, where the features measured during acquisition often vary between samples. Our proposed architecture's capacity to operate seamlessly across incongruent feature spaces is particularly relevant in this context, where data scarcity arises from the low prevalence of the disease. The code is available for research purposes at https://github.com/lisaweijler/FATE.
Label Augmentation As Inter-Class Data Augmentation for Conditional Image Synthesis With Imbalanced Data
Authors: Kai Katsumata; Duc Minh Vo; Hideki Nakayama
Venue: WACV 2024 (main)

Abstract: Conditional image synthesis performs admirably when trained on well-constructed and balanced datasets. However, in practice, training datasets frequently contain minorities (i.e., a class with a few samples), known as imbalanced data, which causes difficulties in learning generative models. To address conditional image synthesis with imbalanced data, we analyze a diversity issue of label-preserving data augmentation and an affinity issue of non-label-preserving data augmentation. From this observation, we present label augmentation, which works as inter-class data augmentation that effectively augments data by predicting a new label for a given image using the prediction of a pretrained image classification model (i.e., probabilities for each class). We incorporate our label augmentation into the discriminator of a seminal conditional generative adversarial network (GAN) model, proposing Softlabel-GAN. Using class probabilities extracts class-invariant and shared features between similar classes, achieving data augmentation with high affinity and diversity. Our experiments on imbalanced datasets show that Softlabel-GAN produces images with high quality and diversity while being hardly affected by the number of samples in each class. Code: https://github.com/raven38/softlabel-gan.
Sign Language Production With Latent Motion Transformer
Authors: Pan Xie; Taiying Peng; Yao Du; Qipeng Zhang
Venue: WACV 2024 (main)

Abstract: Sign Language Production (SLP) is the tough task of turning sign language into sign videos. The main goal of SLP is to create these videos using a sign gloss. In this research, we've developed a new method to make high-quality sign videos without using human poses as a middle step. Our model works in two main parts: first, it learns from a generator and the video's hidden features, and next, it uses another model to understand the order of these hidden features. To make this method even better for sign videos, we make several significant improvements. (i) In the first stage, we take an improved 3D VQ-GAN to learn downsampled latent representations. (ii) In the second stage, we introduce sequence-to-sequence attention to better leverage conditional information. (iii) The separated two-stage training discards the realistic visual semantic of the latent codes in the second stage. To endow the latent sequences semantic information, we extend the token-level autoregressive latent codes learning with perceptual loss and reconstruction loss for the prior model with visual perception. Compared with previous state-of-the-art approaches, our model performs consistently better on two word-level sign language datasets, i.e., WLASL and NMFs-CSL.
Diffused Heads: Diffusion Models Beat GANs on Talking-Face Generation
Authors: Michał Stypułkowski; Konstantinos Vougioukas; Sen He; Maciej Zięba; Stavros Petridis; Maja Pantic
Venue: WACV 2024 (main)

Abstract: Talking face generation has historically struggled to produce head movements and natural facial expressions without guidance from additional reference videos. Recent developments in diffusion-based generative models allow for more realistic and stable data synthesis and their performance on image and video generation has surpassed that of other generative models. In this work, we present an autoregressive diffusion model that requires only one identity image and audio sequence to generate a video of a realistic talking head. Our solution is capable of hallucinating head movements, facial expressions, such as blinks, and preserving a given background. We evaluate our model on two different datasets, achieving state-of-the-art results in expressiveness and smoothness on both of them.
U3DS3: Unsupervised 3D Semantic Scene Segmentation
Authors: Jiaxu Liu; Zhengdi Yu; Toby P. Breckon; Hubert P. H. Shum
Venue: WACV 2024 (main)

Abstract: Contemporary point cloud segmentation approaches largely rely on richly annotated 3D training data. However, it is both time-consuming and challenging to obtain consistently accurate annotations for such 3D scene data. Moreover, there is still a lack of investigation into fully unsupervised scene segmentation for point clouds, especially for holistic 3D scenes. This paper presents U3DS3, as a step towards completely unsupervised point cloud segmentation for any holistic 3D scenes. To achieve this, U3DS3 leverages a generalized unsupervised segmentation method for both object and background across both indoor and outdoor static 3D point clouds with no requirement for model pre-training, by leveraging only the inherent information of the point cloud to achieve full 3D scene segmentation. The initial step of our proposed approach involves generating superpoints based on the geometric characteristics of each scene. Subsequently, it undergoes a learning process through a spatial clustering-based methodology, followed by iterative training using pseudo-labels generated in accordance with the cluster centroids. Moreover, by leveraging the invariance and equivariance of the volumetric representations, we apply the geometric transformation on voxelized features to provide two sets of descriptors for robust representation learning. Finally, our evaluation provides state-of-the-art results on the ScanNet and SemanticKITTI, and competitive results on the S3DIS, benchmark datasets.
GIPCOL: Graph-Injected Soft Prompting for Compositional Zero-Shot Learning
Authors: Guangyue Xu; Joyce Chai; Parisa Kordjamshidi
Venue: WACV 2024 (main)

Abstract: Pre-trained vision-language models (VLMs) have achieved promising success in many fields, specially with prompt learning paradigm. However, designing proper textual prompts to adapt VLMs for downstream tasks is still challenging. In this work, we propose GIPCOL (Graph-Injected soft Prompting for COmpositional Learning) to better explore the compositional zero-shot learning (CZSL) ability of VLMs within the prompt-based learning framework. The soft prompt in GIPCOL is structured and consists of the prefix learnable vectors, attribute label and object label. In addition, the attribute and object labels in the soft prompt are designated as nodes in a compositional graph. The compositional graph is constructed based on the compositional structure of the objects and attributes extracted from the training data and consequently feeds the updated concept representation into the soft prompt to capture this compositional structure for a better CZSL learning. With the new prompting strategy, GIPCOL achieves state-of-the-art AUC results on all three CZSL benchmarks, including MIT-States, UT-Zappos, and C-GQA datasets in both closed and open settings compared to previous non-CLIP as well as CLIP-based methods. We analyze when and why GIPCOL operates well given the CLIP backbone and its training data limitations, and our findings shed light on designing prompts for CZSL.
STEP - Towards Structured Scene-Text Spotting
Authors: Sergi Garcia-Bordils; Dimosthenis Karatzas; Marçal Rusiñol
Venue: WACV 2024 (main)

Abstract: We introduce the structured scene-text spotting task, which requires a scene-text OCR system to spot text in the wild according to a query regular expression. Contrary to generic scene-text OCR, structured scene-text spotting seeks to dynamically condition both detection and recognition on user-provided regular expressions. To tackle this task, we propose the Structured TExt sPotter (STEP), a model that exploits the provided text structure to guide the OCR process. STEP is able to deal with regular expressions that contain spaces and it is not bound to detection at word-level granularity. Our approach enables accurate zero-shot structured text spotting in a wide variety of real-world reading scenarios and is solely trained on publicly available data. To demonstrate the effectiveness of our approach, we introduce a new challenging test dataset that contains several types of out-of-vocabulary structured text, reflecting important reading applications such as weight information, serial numbers, license plates etc. We demonstrate that STEP can provide specialized OCR performance on demand in all tested scenarios. The code and test dataset are released at https://github.com/CVC-DAG/STEP.
ClipSitu: Effectively Leveraging CLIP for Conditional Predictions in Situation Recognition
Authors: Debaditya Roy; Dhruv Verma; Basura Fernando
Venue: WACV 2024 (main)

Abstract: Situation Recognition is the task of generating a structured summary of what is happening in an image using an activity verb and the semantic roles played by actors and objects. In this task, the same activity verb can describe a diverse set of situations as well as the same actor or object category can play a diverse set of semantic roles depending on the situation depicted in the image. Hence a situation recognition model needs to understand the context of the image and the visual-linguistic meaning of semantic roles. Therefore, we leverage the CLIP foundational model that has learned the context of images via language descriptions. We show that deeper-and-wider multi-layer perceptron (MLP) blocks obtain noteworthy results for the situation recognition task by using CLIP image and text embedding features and it even outperforms the state-of-the-art CoFormer, a Transformer-based model, thanks to the external implicit visual-linguistic knowledge encapsulated by CLIP and the expressive power of modern MLP block designs. Motivated by this, we design a cross-attention-based Transformer using CLIP visual tokens that model the relation between textual roles and visual entities. Our cross-attention-based Transformer known as ClipSitu XTF outperforms existing state-of-the-art by a large margin of 14.1% on semantic role labelling (value) for top-1 accuracy using imSitu dataset. Similarly, our ClipSitu XTF obtains state-of-the-art situation localization performance. We will make the code publicly available.