This paper proposes a GeneraLIst encoder-Decoder (GLID) pre-training method for better handling various downstream computer vision tasks. While self-supervised pre-training approaches e.g. Masked Autoencoder have shown success in transfer learning task-specific sub-architectures are still required to be appended for different downstream tasks which cannot enjoy the benefits of large-scale pre-training. GLID overcomes this challenge by allowing the pre-trained generalist encoder-decoder to be fine-tuned on various vision tasks with minimal task-specific architecture modifications. In the GLID training scheme pre-training pretext task and other downstream tasks are modeled as "query-to-answer" problems including the pre-training pretext task and other downstream tasks. We pre-train a task-agnostic encoder-decoder with query-mask pairs. During fine-tuning GLID maintains the pre-trained encoder-decoder and queries only replacing the topmost linear transformation layer with task-specific linear heads. This minimizes the pretrain-finetune architecture inconsistency and enables the pre-trained model to better adapt to downstream tasks. GLID achieves competitive performance on various vision tasks including object detection image segmentation pose estimation and depth estimation outperforming or matching specialist models such as Mask2Former DETR ViTPose and BinsFormer.
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Recent advancements have shown the potential of leveraging both point clouds and images to localize anomalies. Nevertheless their applicability in industrial manufacturing is often constrained by significant drawbacks such as the use of memory banks which leads to a substantial increase in terms of memory footprint and inference times. We propose a novel light and fast framework that learns to map features from one modality to the other on nominal samples and detect anomalies by pinpointing inconsistencies between observed and mapped features. Extensive experiments show that our approach achieves state-of-the-art detection and segmentation performance in both the standard and few-shot settings on the MVTec 3D-AD dataset while achieving faster inference and occupying less memory than previous multimodal AD methods. Furthermore we propose a layer pruning technique to improve memory and time efficiency with a marginal sacrifice in performance.
Crowd counting has achieved significant progress by training regressors to predict instance positions. In heavily crowded scenarios however regressors are challenged by uncontrollable annotation variance which causes density map bias and context information inaccuracy. In this study we propose mutual prompt learning (mPrompt) which leverages a regressor and a segmenter as guidance for each other solving bias and inaccuracy caused by annotation variance while distinguishing foreground from background. In specific mPrompt leverages point annotations to tune the segmenter and predict pseudo head masks in a way of point prompt learning. It then uses the predicted segmentation masks which serve as spatial constraint to rectify biased point annotations as context prompt learning. mPrompt defines a way of mutual information maximization from prompt learning mitigating the impact of annotation variance while improving model accuracy. Experiments show that mPrompt significantly reduces the Mean Average Error (MAE) demonstrating the potential to be general framework for down-stream vision tasks. Code is available at https://github.com/csguomy/mPrompt.
When deploying segmentation models in practice it is critical to evaluate their behaviors in varied and complex scenes. Different from the previous evaluation paradigms only in consideration of global attribute variations (e.g. adverse weather) we investigate both local and global attribute variations for robustness evaluation. To achieve this we construct a mask-preserved attribute editing pipeline to edit visual attributes of real images with precise control of structural information. Therefore the original segmentation labels can be reused for the edited images. Using our pipeline we construct a benchmark covering both object and image attributes (e.g. color material pattern style). We evaluate a broad variety of semantic segmentation models spanning from conventional close-set models to recent open-vocabulary large models on their robustness to different types of variations. We find that both local and global attribute variations affect segmentation performances and the sensitivity of models diverges across different variation types. We argue that local attributes have the same importance as global attributes and should be considered in the robustness evaluation of segmentation models. Code: https://github.com/PRIS-CV/Pascal-EA.
MLIP: Enhancing Medical Visual Representation with Divergence Encoder and Knowledge-guided Contrastive Learning
PDF ↗The scarcity of annotated data has sparked significant interest in unsupervised pre-training methods that leverage medical reports as auxiliary signals for medical visual representation learning. However existing research overlooks the multi-granularity nature of medical visual representation and lacks suitable contrastive learning techniques to improve the models' generalizability across different granularities leading to the underutilization of image-text information. To address this we propose MLIP a novel framework leveraging domain-specific medical knowledge as guiding signals to integrate language information into the visual domain through image-text contrastive learning. Our model includes global contrastive learning with our designed divergence encoder local token-knowledge-patch alignment contrastive learning and knowledge-guided category-level contrastive learning with expert knowledge. Experimental evaluations reveal the efficacy of our model in enhancing transfer performance for tasks such as image classification object detection and semantic segmentation. Notably MLIP surpasses state-of-the-art methods even with limited annotated data highlighting the potential of multimodal pre-training in advancing medical representation learning.
In the realm of video object segmentation (VOS) the challenge of operating under low-light conditions persists resulting in notably degraded image quality and compromised accuracy when comparing query and memory frames for similarity computation. Event cameras characterized by their high dynamic range and ability to capture motion information of objects offer promise in enhancing object visibility and aiding VOS methods under such low-light conditions. This paper introduces a pioneering framework tailored for low-light VOS leveraging event camera data to elevate segmentation accuracy. Our approach hinges on two pivotal components: the Adaptive Cross-Modal Fusion (ACMF) module aimed at extracting pertinent features while fusing image and event modalities to mitigate noise interference and the Event-Guided Memory Matching (EGMM) module designed to rectify the issue of inaccurate matching prevalent in low-light settings. Additionally we present the creation of a synthetic LLE-DAVIS dataset and the curation of a real-world LLE-VOS dataset encompassing frames and events. Experimental evaluations corroborate the efficacy of our method across both datasets affirming its effectiveness in low-light scenarios. The datasets are available at https://github.com/HebeiFast/EventLowLightVOS.
Large Multimodal Models (LMMs) extend Large Language Models to the vision domain. Initial LMMs used holistic images and text prompts to generate ungrounded textual responses. Recently region-level LMMs have been used to generate visually grounded responses. However they are limited to only referring to a single object category at a time require users to specify the regions or cannot offer dense pixel-wise object grounding. In this work we present Grounding LMM (GLaMM) the first model that can generate natural language responses seamlessly intertwined with corresponding object segmentation masks. GLaMM not only grounds objects appearing in the conversations but is flexible enough to accept both textual and optional visual prompts (region of interest) as input. This empowers users to interact with the model at various levels of granularity both in textual and visual domains. Due to the lack of standard benchmarks for the novel setting of visually Grounded Conversation Generation (GCG) we introduce a comprehensive evaluation protocol with our curated grounded conversations. Our proposed GCG task requires densely grounded concepts in natural scenes at a large-scale. To this end we propose a densely annotated Grounding-anything Dataset (GranD) using our proposed automated annotation pipeline that encompasses 7.5M unique concepts grounded in a total of 810M regions available with segmentation masks. Besides GCG GLaMM also performs effectively on several downstream tasks e.g. referring expression segmentation image and region-level captioning and vision-language conversations.
Deciphering 'What' and 'Where' Visual Pathways from Spectral Clustering of Layer-Distributed Neural Representations
PDF ↗We present an approach for analyzing grouping information contained within a neural network's activations permitting extraction of spatial layout and semantic segmentation from the behavior of large pre-trained vision models. Unlike prior work our method conducts a wholistic analysis of a network's activation state leveraging features from all layers and obviating the need to guess which part of the model contains relevant information. Motivated by classic spectral clustering we formulate this analysis in terms of an optimization objective involving a set of affinity matrices each formed by comparing features within a different layer. Solving this optimization problem using gradient descent allows our technique to scale from single images to dataset-level analysis including in the latter both intra- and inter-image relationships. Analyzing a pre-trained generative transformer provides insight into the computational strategy learned by such models. Equating affinity with key-query similarity across attention layers yields eigenvectors encoding scene spatial layout whereas defining affinity by value vector similarity yields eigenvectors encoding object identity. This result suggests that key and query vectors coordinate attentional information flow according to spatial proximity (a `where' pathway) while value vectors refine a semantic category representation (a `what' pathway).
In this paper we address the challenge of image resolution variation for the Segment Anything Model (SAM). SAM known for its zero-shot generalizability exhibits a performance degradation when faced with datasets with varying image sizes. Previous approaches tend to resize the image to a fixed size or adopt structure modifications hindering the preservation of SAM's rich prior knowledge. Besides such task-specific tuning necessitates a complete retraining of the model which is cost-expensive and unacceptable for deployment in the downstream tasks. In this paper we reformulate this challenge as a length extrapolation problem where token sequence length varies while maintaining a consistent patch size for images with different sizes. To this end we propose a Scalable Bias-Mode Attention Mask (BA-SAM) to enhance SAM's adaptability to varying image resolutions while eliminating the need for structure modifications. Firstly we introduce a new scaling factor to ensure consistent magnitude in the attention layer's dot product values when the token sequence length changes. Secondly we present a bias-mode attention mask that allows each token to prioritize neighboring information mitigating the impact of untrained distant information. Our BA-SAM demonstrates efficacy in two scenarios: zero-shot and fine-tuning. Extensive evaluation of diverse datasets including DIS5K DUTS ISIC COD10K and COCO reveals its ability to significantly mitigate performance degradation in the zero-shot setting and achieve state-of-the-art performance with minimal fine-tuning. Furthermore we propose a generalized model and benchmark showcasing BA-SAM's generalizability across all four datasets simultaneously.
Existing few-shot segmentation methods usually extract foreground prototypes from support images to guide query image segmentation. However different background contexts of support and query images can cause their foreground features to be misaligned. This phenomenon known as background context bias can hinder the effectiveness of support prototypes in guiding query image segmentation. In this work we propose a novel framework with an iterative structure to address this problem. In each iteration of the framework we first generate a query prediction based on a support foreground feature. Next we extract background context from the query image to modulate the support foreground feature thus eliminating the foreground feature misalignment caused by the different backgrounds. After that we design a confidence-biased attention to eliminate noise and cleanse information. By integrating these components through an iterative structure we create a novel network that can leverage the synergies between different modules to improve their performance in a mutually reinforcing manner. Through these carefully designed components and structures our network can effectively eliminate background context bias in few-shot segmentation thus achieving outstanding performance. We conduct extensive experiments on the PASCAL-5^ i and COCO-20^ i datasets and achieve state-of-the-art (SOTA) results which demonstrate the effectiveness of our approach.
NeRF-HuGS: Improved Neural Radiance Fields in Non-static Scenes Using Heuristics-Guided Segmentation
PDF ↗Neural Radiance Field (NeRF) has been widely recognized for its excellence in novel view synthesis and 3D scene reconstruction. However their effectiveness is inherently tied to the assumption of static scenes rendering them susceptible to undesirable artifacts when confronted with transient distractors such as moving objects or shadows. In this work we propose a novel paradigm namely "Heuristics-Guided Segmentation" (HuGS) which significantly enhances the separation of static scenes from transient distractors by harmoniously combining the strengths of hand-crafted heuristics and state-of-the-art segmentation models thus significantly transcending the limitations of previous solutions. Furthermore we delve into the meticulous design of heuristics introducing a seamless fusion of Structure-from-Motion (SfM)-based heuristics and color residual heuristics catering to a diverse range of texture profiles. Extensive experiments demonstrate the superiority and robustness of our method in mitigating transient distractors for NeRFs trained in non-static scenes. Project page: https://cnhaox.github.io/NeRF-HuGS/
This paper proposes a cross-modal distillation framework PartDistill which transfers 2D knowledge from vision-language models (VLMs) to facilitate 3D shape part segmentation. PartDistill addresses three major challenges in this task: the lack of 3D segmentation in invisible or undetected regions in the 2D projections inconsistent 2D predictions by VLMs and the lack of knowledge accumulation across different 3D shapes. PartDistill consists of a teacher network that uses a VLM to make 2D predictions and a student network that learns from the 2D predictions while extracting geometrical features from multiple 3D shapes to carry out 3D part segmentation. A bi-directional distillation including forward and backward distillations is carried out within the framework where the former forward distills the 2D predictions to the student network and the latter improves the quality of the 2D predictions which subsequently enhances the final 3D segmentation. Moreover PartDistill can exploit generative models that facilitate effortless 3D shape creation for generating knowledge sources to be distilled. Through extensive experiments PartDistill boosts the existing methods with substantial margins on widely used ShapeNetPart and PartNetE datasets by more than 15% and 12% higher mIoU scores respectively. The code for this work is available at https://github.com/ardianumam/PartDistill.
Few-shot semantic segmentation (FSS) has achieved great success on segmenting objects of novel classes supported by only a few annotated samples. However existing FSS methods often underperform in the presence of domain shifts especially when encountering new domain styles that are unseen during training. It is suboptimal to directly adapt or generalize the entire model to new domains in the few-shot scenario. Instead our key idea is to adapt a small adapter for rectifying diverse target domain styles to the source domain. Consequently the rectified target domain features can fittingly benefit from the well-optimized source domain segmentation model which is intently trained on sufficient source domain data. Training domain-rectifying adapter requires sufficiently diverse target domains. We thus propose a novel local-global style perturbation method to simulate diverse potential target domains by perturbating the feature channel statistics of the individual images and collective statistics of the entire source domain respectively. Additionally we propose a cyclic domain alignment module to facilitate the adapter effectively rectifying domains using a reverse domain rectification supervision. The adapter is trained to rectify the image features from diverse synthesized target domains to align with the source domain. During testing on target domains we start by rectifying the image features and then conduct few-shot segmentation on the domain-rectified features. Extensive experiments demonstrate the effectiveness of our method achieving promising results on cross-domain few-shot semantic segmentation tasks. Our code is available at https://github.com/Matt-Su/DR-Adapter.
Bird's-eye View (BeV) representations have emerged as the de-facto shared space in driving applications offering a unified space for sensor data fusion and supporting various downstream tasks. However conventional models use grids with fixed resolution and range and face computational inefficiencies due to the uniform allocation of resources across all cells. To address this we propose PointBeV a novel sparse BeV segmentation model operating on sparse BeV cells instead of dense grids. This approach offers precise control over memory usage enabling the use of long temporal contexts and accommodating memory-constrained platforms. PointBeV employs an efficient two-pass strategy for training enabling focused computation on regions of interest. At inference time it can be used with various memory/performance trade-offs and flexibly adjusts to new specific use cases. PointBeV achieves state-of-the-art results on the nuScenes dataset for vehicle pedestrian and lane segmentation showcasing superior performance in static and temporal settings despite being trained solely with sparse signals. We release our code with two new efficient modules used in the architecture: Sparse Feature Pulling designed for the effective extraction of features from images to BeV and Submanifold Attention which enables efficient temporal modeling. The code is available at https://github.com/valeoai/PointBeV.
Recent advances in vision-language models like Stable Diffusion have shown remarkable power in creative image synthesis and editing.However most existing text-to-image editing methods encounter two obstacles: First the text prompt needs to be carefully crafted to achieve good results which is not intuitive or user-friendly. Second they are insensitive to local edits and can irreversibly affect non-edited regions leaving obvious editing traces. To tackle these problems we propose a Zero-shot instructiON-guided local image Editing approach termed ZONE. We first convert the editing intent from the user-provided instruction (e.g. "make his tie blue") into specific image editing regions through InstructPix2Pix. We then propose a Region-IoU scheme for precise image layer extraction from an off-the-shelf segment model. We further develop an edge smoother based on FFT for seamless blending between the layer and the image.Our method allows for arbitrary manipulation of a specific region with a single instruction while preserving the rest. Extensive experiments demonstrate that our ZONE achieves remarkable local editing results and user-friendliness outperforming state-of-the-art methods. Code is available at https://github.com/lsl001006/ZONE.
Utilizing multi-view inputs to synthesize novel-view images Neural Radiance Fields (NeRF) have emerged as a popular research topic in 3D vision. In this work we introduce a Generalizable Semantic Neural Radiance Field (GSNeRF) which uniquely takes image semantics into the synthesis process so that both novel view images and the associated semantic maps can be produced for unseen scenes. Our GSNeRF is composed of two stages: Semantic Geo-Reasoning and Depth-Guided Visual rendering. The former is able to observe multi-view image inputs to extract semantic and geometry features from a scene. Guided by the resulting image geometry information the latter performs both image and semantic rendering with improved performances. Our experiments not only confirm that GSNeRF performs favorably against prior works on both novel-view image and semantic segmentation synthesis but the effectiveness of our sampling strategy for visual rendering is further verified.
Recent works utilize CLIP to perform the challenging unsupervised semantic segmentation task where only images without annotations are available. However we observe that when adopting CLIP to such a pixel-level understanding task unexpected bias occurs. Previous works don't explicitly model such bias which largely constrains the segmentation performance. In this paper we propose to explicitly model and rectify the bias existing in CLIP to facilitate the unsupervised semantic segmentation. Specifically we design a learnable "Reference" prompt to encode class-preference bias and project the positional embedding of vision transformer to represent space-preference bias. Via a simple element-wise subtraction we rectify the logits of CLIP classifier. Based on the rectified logits we generate a segmentation mask via a Gumbel-Softmax operation. Then a contrastive loss between masked visual feature and the text features of different classes is imposed to facilitate the effective bias modeling. To further improve the segmentation we distill the knowledge from the rectified CLIP to the advanced segmentation architecture via minimizing our designed mask-guided feature-guided and text-guided loss terms. Extensive experiments on standard benchmarks demonstrate that our method performs favorably against previous state-of-the-arts. The implementation is available at https://github.com/dogehhh/ReCLIP.
Test-time adaptation (TTA) is a technique to improve the performance of a pre-trained source model on a target distribution without using any labeled data. However existing self-trained TTA methods often face the challenges of unreliable pseudo-labels and unstable model optimization. In this paper we propose an Improved Self-Training (IST) approach which addresses these challenges by enhancing the pseudo-label quality and stabilizing the adaptation process. Specifically we use a simple augmentation strategy to generate multiple views of each test sample and construct a graph structure to correct the pseudo-labels based on the similarity of the latent features. Moreover we adopt a parameter moving average scheme to smooth the model updates and prevent catastrophic forgetting. Instead of using a model with fixed label space we explore the adaptability of the foundation model CLIP to various downstream tasks at test time. Extensive experiments on various benchmarks show that IST can achieve significant and consistent improvements over the existing TTA methods in classification detection and segmentation tasks.
Recently we have witnessed the explosive growth of various volumetric representations in modeling animatable head avatars. However due to the diversity of frameworks there is no practical method to support high-level applications like 3D head avatar editing across different representations. In this paper we propose a generic avatar editing approach that can be universally applied to various 3DMM driving volumetric head avatars. To achieve this goal we design a novel expression-aware modification generative model which enables lift 2D editing from a single image to a consistent 3D modification field. To ensure the effectiveness of the generative modification process we develop several techniques including an expression-dependent modification distillation scheme to draw knowledge from the large-scale head avatar model and 2D facial texture editing tools implicit latent space guidance to enhance model convergence and a segmentation-based loss reweight strategy for fine-grained texture inversion. Extensive experiments demonstrate that our method delivers high-quality and consistent results across multiple expression and viewpoints. Project page: https://zju3dv.github.io/ geneavatar/.
Cooperation Does Matter: Exploring Multi-Order Bilateral Relations for Audio-Visual Segmentation
PDF ↗Recently an audio-visual segmentation (AVS) task has been introduced aiming to group pixels with sounding objects within a given video. This task necessitates a first-ever audio-driven pixel-level understanding of the scene posing significant challenges. In this paper we propose an innovative audio-visual transformer framework termed COMBO an acronym for COoperation of Multi-order Bilateral relatiOns. For the first time our framework explores three types of bilateral entanglements within AVS: pixel entanglement modality entanglement and temporal entanglement. Regarding pixel entanglement we employ a Siam-Encoder Module (SEM) that leverages prior knowledge to generate more precise visual features from the foundational model. For modality entanglement we design a Bilateral-Fusion Module (BFM) enabling COMBO to align corresponding visual and auditory signals bi-directionally. As for temporal entanglement we introduce an innovative adaptive inter-frame consistency loss according to the inherent rules of temporal. Comprehensive experiments and ablation studies on AVSBench-object (84.7 mIoU on S4 59.2 mIou on MS3) and AVSBench-semantic (42.1 mIoU on AVSS) datasets demonstrate that COMBO surpasses previous state-of-the-art methods. Project page is available at https://yannqi.github.io/AVS-COMBO.