Class-agnostic object counting aims to count all objects in an image with respect to example boxes or class names a.k.a few-shot and zero-shot counting. In this paper we propose a generalized framework for both few-shot and zero-shot object counting based on detection. Our framework combines the superior advantages of two foundation models without compromising their zero-shot capability: (i) SAM to segment all possible objects as mask proposals and (ii) CLIP to classify proposals to obtain accurate object counts. However this strategy meets the obstacles of efficiency overhead and the small crowded objects that cannot be localized and distinguished. To address these issues our framework termed PseCo follows three steps: point segment and count. Specifically we first propose a class-agnostic object localization to provide accurate but least point prompts for SAM which consequently not only reduces computation costs but also avoids missing small objects. Furthermore we propose a generalized object classification that leverages CLIP image/text embeddings as the classifier following a hierarchical knowledge distillation to obtain discriminative classifications among hierarchical mask proposals. Extensive experimental results on FSC-147 COCO and LVIS demonstrate that PseCo achieves state-of-the-art performance in both few-shot/zero-shot object counting/detection.
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SCULPT: Shape-Conditioned Unpaired Learning of Pose-dependent Clothed and Textured Human Meshes
PDF ↗We present SCULPT a novel 3D generative model for clothed and textured 3D meshes of humans. Specifically we devise a deep neural network that learns to represent the geometry and appearance distribution of clothed human bodies. Training such a model is challenging as datasets of textured 3D meshes for humans are limited in size and accessibility. Our key observation is that there exist medium-sized 3D scan datasets like CAPE as well as large-scale 2D image datasets of clothed humans and multiple appearances can be mapped to a single geometry. To effectively learn from the two data modalities we propose an unpaired learning procedure for pose-dependent clothed and textured human meshes. Specifically we learn a pose-dependent geometry space from 3D scan data. We represent this as per vertex displacements w.r.t. the SMPL model. Next we train a geometry conditioned texture generator in an unsupervised way using the 2D image data. We use intermediate activations of the learned geometry model to condition our texture generator. To alleviate entanglement between pose and clothing type and pose and clothing appearance we condition both the texture and geometry generators with attribute labels such as clothing types for the geometry and clothing colors for the texture generator. We automatically generated these conditioning labels for the 2D images based on the visual question-answering model BLIP and CLIP. We validate our method on the SCULPT dataset and compare to state-of-the-art 3D generative models for clothed human bodies. Our code and data can be found at https://sculpt.is.tue.mpg.de.
Video-based Unsupervised Domain Adaptation (VUDA) method improves the generalization of the video model enabling it to be applied to action recognition tasks in different environments. However these methods require continuous access to source data during the adaptation process which are impractical in real scenarios where the source videos are not available with concerns in transmission efficiency or privacy issues. To address this problem in this paper we propose to solve the Multimodal Video Test-Time Adaptation task (MVTTA). Existing image-based TTA methods cannot be directly applied to this task because video have domain shift in multimodal and temporal which brings difficulties to adaptation. To address the above challenges we propose a Modality-Collaborative Test-Time Adaptation (MC-TTA) Network. We maintain teacher and student memory banks respectively for generating pseudo-prototypes and target-prototypes. In the teacher model we propose Self-assembled Source-friendly Feature Reconstruction (SSFR) module to encourage the teacher memory bank to store features that are more likely to be consistent with the source distribution. Through multimodal prototype alignment and cross-modal relative consistency our method can effectively alleviate domain shift in videos. We evaluate the proposed model on four public video datasets. The results show that our model outperforms existing state-of-the-art methods.
Video prediction is a challenging task due to its nature of uncertainty especially for forecasting a long period. To model the temporal dynamics advanced methods benefit from the recent success of diffusion models and repeatedly refine the predicted future frames with 3D spatiotemporal U-Net. However there exists a gap between the present and future and the repeated usage of U-Net brings a heavy computation burden. To address this we propose a diffusion-based video prediction method that predicts future frames by extrapolating the present distribution of features namely ExtDM. Specifically our method consists of three components: (i) a motion autoencoder conducts a bijection transformation between video frames and motion cues; (ii) a layered distribution adaptor module extrapolates the present features in the guidance of Gaussian distribution; (iii) a 3D U-Net architecture specialized for jointly fusing guidance and features among the temporal dimension by spatiotemporal-window attention. Extensive experiments on five popular benchmarks covering short- and long-term video prediction verify the effectiveness of ExtDM.
Large motion poses a critical challenge in Video Frame Interpolation (VFI) task. Existing methods are often constrained by limited receptive fields resulting in sub-optimal performance when handling scenarios with large motion. In this paper we introduce a new pipeline for VFI which can effectively integrate global-level information to alleviate issues associated with large motion. Specifically we first estimate a pair of initial intermediate flows using a high-resolution feature map for extracting local details. Then we incorporate a sparse global matching branch to compensate for flow estimation which consists of identifying flaws in initial flows and generating sparse flow compensation with a global receptive field. Finally we adaptively merge the initial flow estimation with global flow compensation yielding a more accurate intermediate flow. To evaluate the effectiveness of our method in handling large motion we carefully curate a more challenging subset from commonly used benchmarks. Our method demonstrates the state-of-the-art performance on these VFI subsets with large motion.
Numerous studies have demonstrated the susceptibility of deep neural networks (DNNs) to subtle adversarial perturbations prompting the development of many advanced adversarial defense methods aimed at mitigating adversarial attacks. Current defense strategies usually train DNNs for a specific adversarial attack method and can achieve good robustness in defense against this type of adversarial attack. Nevertheless when subjected to evaluations involving unfamiliar attack modalities empirical evidence reveals a pronounced deterioration in the robustness of DNNs. Meanwhile there is a trade-off between the classification accuracy of clean examples and adversarial examples. Most defense methods often sacrifice the accuracy of clean examples in order to improve the adversarial robustness of DNNs. To alleviate these problems and enhance the overall robust generalization of DNNs we propose the Test-Time Pixel-Level Adversarial Purification (TPAP) method. This approach is based on the robust overfitting characteristic of DNNs to the fast gradient sign method (FGSM) on training and test datasets. It utilizes FGSM for adversarial purification to process images for purifying unknown adversarial perturbations from pixels at testing time in a "counter changes with changelessness" manner thereby enhancing the defense capability of DNNs against various unknown adversarial attacks. Extensive experimental results show that our method can effectively improve both overall robust generalization of DNNs notably over previous methods. Code is available https://github.com/tly18/TPAP.
Text-driven video generation witnesses rapid progress. However merely using text prompts is not enough to depict the desired subject appearance that accurately aligns with users' intents especially for customized content creation. In this paper we study the task of video generation with image prompts which provide more accurate and direct content control beyond the text prompts. Specifically we propose a feed-forward framework VideoBooth with two dedicated designs: 1) We propose to embed image prompts in a coarse-to-fine manner. Coarse visual embeddings from image encoder provide high-level encodings of image prompts while fine visual embeddings from the proposed attention injection module provide multi-scale and detailed encoding of image prompts. These two complementary embeddings can faithfully capture the desired appearance. 2) In the attention injection module at fine level multi-scale image prompts are fed into different cross-frame attention layers as additional keys and values. This extra spatial information refines the details in the first frame and then it is propagated to the remaining frames which maintains temporal consistency. Extensive experiments demonstrate that VideoBooth achieves state-of-the-art performance in generating customized high-quality videos with subjects specified in image prompts. Notably VideoBooth is a generalizable framework where a single model works for a wide range of image prompts with only feed-forward passes.
Prompt learning has emerged as a valuable technique in enhancing vision-language models (VLMs) such as CLIP for downstream tasks in specific domains. Existing work mainly focuses on designing various learning forms of prompts neglecting the potential of prompts as effective distillers for learning from larger teacher models. In this paper we introduce an unsupervised domain prompt distillation framework which aims to transfer the knowledge of a larger teacher model to a lightweight target model through prompt-driven imitation using unlabeled domain images. Specifically our framework consists of two distinct stages. In the initial stage we pre-train a large CLIP teacher model using domain (few-shot) labels. After pre-training we leverage the unique decoupled-modality characteristics of CLIP by pre-computing and storing the text features as class vectors only once through the teacher text encoder. In the subsequent stage the stored class vectors are shared across teacher and student image encoders for calculating the predicted logits. Further we align the logits of both the teacher and student models via KL divergence encouraging the student image encoder to generate similar probability distributions to the teacher through the learnable prompts. The proposed prompt distillation process eliminates the reliance on labeled data enabling the algorithm to leverage a vast amount of unlabeled images within the domain. Finally the well-trained student image encoders and pre-stored text features (class vectors) are utilized for inference. To our best knowledge we are the first to (1) perform unsupervised domain-specific prompt-driven knowledge distillation for CLIP and (2) establish a practical pre-storing mechanism of text features as shared class vectors between teacher and student. Extensive experiments on 11 datasets demonstrate the effectiveness of our method. Code is publicly available at https://github.com/zhengli97/PromptKD.
Inferring scene geometry from images via Structure from Motion is a long-standing and fundamental problem in computer vision. While classical approaches and more recently depth map predictions only focus on the visible parts of a scene the task of scene completion aims to reason about geometry even in occluded regions. With the popularity of NeRF implicit representations also became popular for scene completion by predicting so-called density fields. Unlike explicit approaches e.g. voxel-based methods density fields also allow for accurate depth prediction and novel-view synthesis via image-based rendering. In this work we propose to fuse the scene reconstruction from multiple images and distill this knowledge into a more accurate single-view scene reconstruction. To this end we propose MVBTS to fuse density fields from multiple posed images trained fully self-supervised only from image data. Using knowledge distillation we use MVBTS to train a single-view scene completion network via direct supervision called KDBTS. It achieves state-of-the-art performance on occupancy prediction especially in occluded regions.
Geometry-aware Reconstruction and Fusion-refined Rendering for Generalizable Neural Radiance Fields
PDF ↗Generalizable NeRF aims to synthesize novel views for unseen scenes. Common practices involve constructing variance-based cost volumes for geometry reconstruction and encoding 3D descriptors for decoding novel views. However existing methods show limited generalization ability in challenging conditions due to inaccurate geometry sub-optimal descriptors and decoding strategies. We address these issues point by point. First we find the variance-based cost volume exhibits failure patterns as the features of pixels corresponding to the same point can be inconsistent across different views due to occlusions or reflections. We introduce an Adaptive Cost Aggregation (ACA) approach to amplify the contribution of consistent pixel pairs and suppress inconsistent ones. Unlike previous methods that solely fuse 2D features into descriptors our approach introduces a Spatial-View Aggregator (SVA) to incorporate 3D context into descriptors through spatial and inter-view interaction. When decoding the descriptors we observe the two existing decoding strategies excel in different areas which are complementary. A Consistency-Aware Fusion (CAF) strategy is proposed to leverage the advantages of both. We incorporate the above ACA SVA and CAF into a coarse-to-fine framework termed Geometry-aware Reconstruction and Fusion-refined Rendering (GeFu). GeFu attains state-of-the-art performance across multiple datasets.
Existing super-resolution (SR) models primarily focus on restoring local texture details often neglecting the global semantic information within the scene. This oversight can lead to the omission of crucial semantic details or the introduction of inaccurate textures during the recovery process. In our work we introduce the Cognitive Super-Resolution (CoSeR) framework empowering SR models with the capacity to comprehend low-resolution images. We achieve this by marrying image appearance and language understanding to generate a cognitive embedding which not only activates prior information from large text-to-image diffusion models but also facilitates the generation of high-quality reference images to optimize the SR process. To further improve image fidelity we propose a novel condition injection scheme called "All-in-Attention" consolidating all conditional information into a single module. Consequently our method successfully restores semantically correct and photorealistic details demonstrating state-of-the-art performance across multiple benchmarks. Project page: https://coser-main.github.io/
As manipulating images may lead to misinterpretation of the visual content addressing the image forgery detection and localization (IFDL) problem has drawn serious public concerns. In this work we propose a simple assumption that the effective forensic method should focus on the mesoscopic properties of images. Based on the assumption a novel two-stage self-supervised framework leveraging the diffusion model for IFDL task i.e. DiffForensics is proposed in this paper. The DiffForensics begins with self-supervised denoising diffusion paradigm equipped with the module of encoder-decoder structure by freezing the pre-trained encoder (e.g. in ADE-20K) to inherit macroscopic features for general image characteristics while encouraging the decoder to learn microscopic feature representation of images enforcing the whole model to focus the mesoscopic representations. The pre-trained model as a prior is then further fine-tuned for IFDL task with the customized Edge Cue Enhancement Module (ECEM) which progressively highlights the boundary features within the manipulated regions thereby refining tampered area localization with better precision. Extensive experiments on several public challenging datasets demonstrate the effectiveness of the proposed method compared with other state-of-the-art methods. The proposed DiffForensics could significantly improve the model's capabilities for both accurate tamper detection and precise tamper localization while concurrently elevating its generalization and robustness.
HiPose: Hierarchical Binary Surface Encoding and Correspondence Pruning for RGB-D 6DoF Object Pose Estimation
PDF ↗In this work we present a novel dense-correspondence method for 6DoF object pose estimation from a single RGB-D image. While many existing data-driven methods achieve impressive performance they tend to be time-consuming due to their reliance on rendering-based refinement approaches. To circumvent this limitation we present HiPose which establishes 3D-3D correspondences in a coarse-to-fine manner with a hierarchical binary surface encoding. Unlike previous dense-correspondence methods we estimate the correspondence surface by employing point-to-surface matching and iteratively constricting the surface until it becomes a correspondence point while gradually removing outliers. Extensive experiments on public benchmarks LM-O YCB-V and T-Less demonstrate that our method surpasses all refinement-free methods and is even on par with expensive refinement-based approaches. Crucially our approach is computationally efficient and enables real-time critical applications with high accuracy requirements.
Selective Interpretable and Motion Consistent Privacy Attribute Obfuscation for Action Recognition
PDF ↗Concerns for the privacy of individuals captured in public imagery have led to privacy-preserving action recognition. Existing approaches often suffer from issues arising through obfuscation being applied globally and a lack of interpretability. Global obfuscation hides privacy sensitive regions but also contextual regions important for action recognition. Lack of interpretability erodes trust in these new technologies. We highlight the limitations of current paradigms and propose a solution: Human selected privacy templates that yield interpretability by design an obfuscation scheme that selectively hides attributes and also induces temporal consistency which is important in action recognition. Our approach is architecture agnostic and directly modifies input imagery while existing approaches generally require architecture training. Our approach offers more flexibility as no retraining is required and outperforms alternatives on three widely used datasets.
Visual Delta Generator with Large Multi-modal Models for Semi-supervised Composed Image Retrieval
PDF ↗Composed Image Retrieval (CIR) is a task that retrieves images similar to a query based on a provided textual modification. Current techniques rely on supervised learning for CIR models using labeled triplets of the <reference image text target image>. These specific triplets are not as commonly available as simple image-text pairs limiting the widespread use of CIR and its scalability. On the other hand zero-shot CIR can be relatively easily trained with image-caption pairs without considering the image-to-image relation but this approach tends to yield lower accuracy. We propose a new semi-supervised CIR approach where we search for a reference and its related target images in auxiliary data and learn our large language model-based Visual Delta Generator (VDG) to generate text describing the visual difference (i.e. visual delta) between the two. VDG equipped with fluent language knowledge and being model agnostic can generate pseudo triplets to boost the performance of CIR models. Our approach significantly improves the existing supervised learning approaches and achieves state-of-the-art results on the CIR benchmarks.
UniMix: Towards Domain Adaptive and Generalizable LiDAR Semantic Segmentation in Adverse Weather
PDF ↗LiDAR semantic segmentation (LSS) is a critical task in autonomous driving and has achieved promising progress. However prior LSS methods are conventionally investigated and evaluated on datasets within the same domain in clear weather. The robustness of LSS models in unseen scenes and all weather conditions is crucial for ensuring safety and reliability in real applications. To this end we propose UniMix a universal method that enhances the adaptability and generalizability of LSS models. UniMix first leverages physically valid adverse weather simulation to construct a Bridge Domain which serves to bridge the domain gap between the clear weather scenes and the adverse weather scenes. Then a Universal Mixing operator is defined regarding spatial intensity and semantic distributions to create the intermediate domain with mixed samples from given domains. Integrating the proposed two techniques into a teacher-student framework UniMix efficiently mitigates the domain gap and enables LSS models to learn weather-robust and domain-invariant representations. We devote UniMix to two main setups: 1) unsupervised domain adaption adapting the model from the clear weather source domain to the adverse weather target domain; 2) domain generalization learning a model that generalizes well to unseen scenes in adverse weather. Extensive experiments validate the effectiveness of UniMix across different tasks and datasets all achieving superior performance over state-of-the-art methods. The code will be released.
Dataset pruning aims to construct a coreset capable of achieving performance comparable to the original full dataset. Most existing dataset pruning methods rely on snapshot-based criteria to identify representative samples often resulting in poor generalization across various pruning and cross-architecture scenarios. Recent studies have addressed this issue by expanding the scope of training dynamics considered including factors such as forgetting event and probability change typically using an averaging approach. However these works struggle to integrate a broader range of training dynamics without overlooking well-generalized samples which may not be sufficiently highlighted in an averaging manner. In this study we propose a novel dataset pruning method termed as Temporal Dual-Depth Scoring (TDDS) to tackle this problem. TDDS utilizes a dual-depth strategy to achieve a balance between incorporating extensive training dynamics and identifying representative samples for dataset pruning. In the first depth we estimate the series of each sample's individual contributions spanning the training progress ensuring comprehensive integration of training dynamics. In the second depth we focus on the variability of the sample-wise contributions identified in the first depth to highlight well-generalized samples. Extensive experiments conducted on CIFAR and ImageNet datasets verify the superiority of TDDS over previous SOTA methods. Specifically on CIFAR-100 our method achieves 54.51% accuracy with only 10% training data surpassing baselines methods by more than 12.69%. Our codes are available at https://github.com/zhangxin-xd/Dataset-Pruning-TDDS.
Strong Transferable Adversarial Attacks via Ensembled Asymptotically Normal Distribution Learning
PDF ↗Strong adversarial examples are crucial for evaluating and enhancing the robustness of deep neural networks. However the performance of popular attacks is usually sensitive for instance to minor image transformations stemming from limited information -- typically only one input example a handful of white-box source models and undefined defense strategies. Hence the crafted adversarial examples are prone to overfit the source model which hampers their transferability to unknown architectures. In this paper we propose an approach named Multiple Asymptotically Normal Distribution Attacks (MultiANDA) which explicitly characterize adversarial perturbations from a learned distribution. Specifically we approximate the posterior distribution over the perturbations by taking advantage of the asymptotic normality property of stochastic gradient ascent (SGA) then employ the deep ensemble strategy as an effective proxy for Bayesian marginalization in this process aiming to estimate a mixture of Gaussians that facilitates a more thorough exploration of the potential optimization space. The approximated posterior essentially describes the stationary distribution of SGA iterations which captures the geometric information around the local optimum. Thus MultiANDA allows drawing an unlimited number of adversarial perturbations for each input and reliably maintains the transferability. Our proposed method outperforms ten state-of-the-art black-box attacks on deep learning models with or without defenses through extensive experiments on seven normally trained and seven defense models.
Seg2Reg: Differentiable 2D Segmentation to 1D Regression Rendering for 360 Room Layout Reconstruction
PDF ↗State-of-the-art single-view 360 room layout reconstruction methods formulate the problem as a high-level 1D (per-column) regression task. On the other hand traditional low-level 2D layout segmentation is simpler to learn and can represent occluded regions but it requires complex post-processing for the targeting layout polygon and sacrifices accuracy. We present Seg2Reg to render 1D layout depth regression from the 2D segmentation map in a differentiable and occlusion-aware way marrying the merits of both sides. Specifically our model predicts floor-plan density for the input equirectangular 360 image. Formulating the 2D layout representation as a density field enables us to employ 'flattened' volume rendering to form 1D layout depth regression. In addition we propose a novel 3D warping augmentation on layout to improve generalization. Finally we re-implement recent room layout reconstruction methods into our codebase for benchmarking and explore modern backbones and training techniques to serve as the strong baseline. The code is at https: //PanoLayoutStudio.github.io .
Text-to-motion tasks have been the focus of recent advancements in the human motion domain. However the performance of text-to-motion tasks have not reached its potential primarily due to the lack of motion datasets and the pronounced gap between the text and motion modalities. To mitigate this challenge we introduce VLMA a novel Video-Language-Motion Alignment method. This approach leverages human-centric videos as an intermediary modality effectively bridging the divide between text and motion. By employing contrastive learning we construct a cohesive embedding space across the three modalities. Furthermore we incorporate a motion reconstruction branch ensuring that the resulting motion remains closely aligned with its original trajectory. Experimental evaluations on the HumanML3D and KIT-ML datasets demonstrate the superiority of our method in comparison to existing approaches. Furthermore we introduce a novel task termed video-to-motion retrieval designed to facilitate the seamlessxt eraction of corresponding 3D motions from an RGB video. Supplementary experiments demonstrate that our model is extensible to real-world human-centric videos offering a valuable complement to the pose estimation task.