215,320 research outputs found
Spectral-Spatial Graph Reasoning Network for Hyperspectral Image Classification
In this paper, we propose a spectral-spatial graph reasoning network (SSGRN)
for hyperspectral image (HSI) classification. Concretely, this network contains
two parts that separately named spatial graph reasoning subnetwork (SAGRN) and
spectral graph reasoning subnetwork (SEGRN) to capture the spatial and spectral
graph contexts, respectively. Different from the previous approaches
implementing superpixel segmentation on the original image or attempting to
obtain the category features under the guide of label image, we perform the
superpixel segmentation on intermediate features of the network to adaptively
produce the homogeneous regions to get the effective descriptors. Then, we
adopt a similar idea in spectral part that reasonably aggregating the channels
to generate spectral descriptors for spectral graph contexts capturing. All
graph reasoning procedures in SAGRN and SEGRN are achieved through graph
convolution. To guarantee the global perception ability of the proposed
methods, all adjacent matrices in graph reasoning are obtained with the help of
non-local self-attention mechanism. At last, by combining the extracted spatial
and spectral graph contexts, we obtain the SSGRN to achieve a high accuracy
classification. Extensive quantitative and qualitative experiments on three
public HSI benchmarks demonstrate the competitiveness of the proposed methods
compared with other state-of-the-art approaches
Higher-level Representations of Natural Images
PhDThe traditional view of vision is that neurons in early cortical areas process information about simple features (e.g. orientation and spatial frequency) in small, spatially localised regions of visual space (the neuronâs receptive field). This piecemeal information is then fed-forward into later stages of the visual system where it gets combined to form coherent and meaningful global (higher-level) representations. The overall aim of this thesis is to examine and quantify this higher level processing; how we encode global features in natural images and to understand the extent to which our perception of these global representations is determined by the local features within images. Using the tilt after-effect as a tool, the first chapter examined the processing of a low level, local feature and found that the orientation of a sinusoidal grating could be encoded in both a retinally and spatially non-specific manner. Chapter 2 then examined these tilt aftereffects to the global orientation of the image (i.e., uprightness). We found that image uprightness was also encoded in a retinally / spatially non-specific manner, but that this global property could be processed largely independently of its local orientation content. Chapter 3 investigated if our increased sensitivity to cardinal (vertical and horizontal) structures compared to inter-cardinal (45° and 135° clockwise of vertical) structures, influenced classification of unambiguous natural images. Participants required relatively less contrast to classify images when they retained near-cardinal as compared to near-inter-cardinal structures. Finally, in chapter 4, we examined category classification when images were ambiguous. Observers were biased to classify ambiguous images, created by combining structures from two distinct image categories, as carpentered (e.g., a house). This could not be explained by differences in sensitivity to local structures and is most likely the result of our long-term exposure to city views. Overall, these results show that higher-level representations are not fully dependent on the lower level features within an image. Furthermore, our knowledge about the environment influences the extent to which we use local features to rapidly identify an image.Queen Mary University of London PhD studentship
SpaSSA: superpixelwise adaptive SSA for unsupervised spatial-spectral feature extraction in hyperspectral image.
Singular spectral analysis (SSA) has recently been successfully applied to feature extraction in hyperspectral image (HSI), including conventional (1-D) SSA in spectral domain and 2-D SSA in spatial domain. However, there are some drawbacks, such as sensitivity to the window size, high computational complexity under a large window, and failing to extract joint spectral-spatial features. To tackle these issues, in this article, we propose superpixelwise adaptive SSA (SpaSSA), that is superpixelwise adaptive SSA for exploiting local spatial information of HSI. The extraction of local (instead of global) features, particularly in HSI, can be more effective for characterizing the objects within an image. In SpaSSA, conventional SSA and 2-D SSA are combined and adaptively applied to each superpixel derived from an oversegmented HSI. According to the size of the derived superpixels, either SSA or 2-D singular spectrum analysis (2D-SSA) is adaptively applied for feature extraction, where the embedding window in 2D-SSA is also adaptive to the size of the superpixel. Experimental results on the three datasets have shown that the proposed SpaSSA outperforms both SSA and 2D-SSA in terms of classification accuracy and computational complexity. By combining SpaSSA with the principal component analysis (SpaSSA-PCA), the accuracy of land-cover analysis can be further improved, outperforming several state-of-the-art approaches
Recommended from our members
Integrating domain knowledge and deep learning for enhanced chest X-ray diagnosis and localization
Chest X-ray imaging has become increasingly crucial for diagnosing various medical conditions, including pneumonia, lung cancer, and heart diseases. Despite the growing number of chest X-ray images, their interpretation remains a manual and time-consuming process, often leading to radiologist burnout and delays in diagnosis. The integration of domain knowledge and deep learning techniques has the potential to improve diagnosis, classification, and localization of abnormalities in chest X-rays, while also addressing the challenge of model interpretability.
This work proposes a series of novel methods combining radiomics features and deep learning techniques for chest X-ray diagnosis, classification, and localization. We first introduce a framework leveraging radiomics features and contrastive learning for pneumonia detection, achieving superior performance and interpretability. The second method, ChexRadiNet, utilizes radiomics features and a lightweight triplet-attention mechanism for enhanced abnormality classification performance.
In addition, we present a semi-supervised knowledge-augmented contrastive learning framework that seamlessly integrates radiomic features as a knowledge augmentation for disease classification and localization. This approach leverages Grad-CAM to highlight crucial abnormal regions, extracting radiomic features that act as positive samples for image features generated from the same chest X-ray. Consequently, this framework creates a feedback loop, enabling image and radiomic features to mutually reinforce each other, resulting in robust and interpretable knowledge-augmented representations.
The Radiomics-Guided Transformer (RGT) fuses global image information with local radiomics-guided auxiliary information for accurate cardiopulmonary pathology localization and classification without bounding box annotations.
Experimental results on public datasets such as NIH ChestX-ray, CheXpert, MIMIC-CXR, and the RSNA Pneumonia Detection Challenge demonstrate the effectiveness of our proposed methods, consistently outperforming state-of-the-art models in chest X-ray diagnosis, classification, and localization tasks. By bridging the gap between traditional radiomics and deep learning approaches, this work aims to advance the field of medical image analysis and facilitate more efficient and accurate diagnoses in clinical practice.Electrical and Computer Engineerin
Hybrid image representation methods for automatic image annotation: a survey
In most automatic image annotation systems, images are represented with low level features using either global
methods or local methods. In global methods, the entire image is used as a unit. Local methods divide images into blocks where fixed-size sub-image blocks are adopted as sub-units; or into regions by using segmented regions as sub-units in images. In contrast to typical automatic image annotation methods that use either global or local features exclusively, several recent methods have considered incorporating the two kinds of information, and believe that the combination of the two levels of features is
beneficial in annotating images. In this paper, we provide a
survey on automatic image annotation techniques according to
one aspect: feature extraction, and, in order to complement
existing surveys in literature, we focus on the emerging image annotation methods: hybrid methods that combine both global and local features for image representation
Multi-scale Orderless Pooling of Deep Convolutional Activation Features
Deep convolutional neural networks (CNN) have shown their promise as a
universal representation for recognition. However, global CNN activations lack
geometric invariance, which limits their robustness for classification and
matching of highly variable scenes. To improve the invariance of CNN
activations without degrading their discriminative power, this paper presents a
simple but effective scheme called multi-scale orderless pooling (MOP-CNN).
This scheme extracts CNN activations for local patches at multiple scale
levels, performs orderless VLAD pooling of these activations at each level
separately, and concatenates the result. The resulting MOP-CNN representation
can be used as a generic feature for either supervised or unsupervised
recognition tasks, from image classification to instance-level retrieval; it
consistently outperforms global CNN activations without requiring any joint
training of prediction layers for a particular target dataset. In absolute
terms, it achieves state-of-the-art results on the challenging SUN397 and MIT
Indoor Scenes classification datasets, and competitive results on
ILSVRC2012/2013 classification and INRIA Holidays retrieval datasets
ParseNet: Looking Wider to See Better
We present a technique for adding global context to deep convolutional
networks for semantic segmentation. The approach is simple, using the average
feature for a layer to augment the features at each location. In addition, we
study several idiosyncrasies of training, significantly increasing the
performance of baseline networks (e.g. from FCN). When we add our proposed
global feature, and a technique for learning normalization parameters, accuracy
increases consistently even over our improved versions of the baselines. Our
proposed approach, ParseNet, achieves state-of-the-art performance on SiftFlow
and PASCAL-Context with small additional computational cost over baselines, and
near current state-of-the-art performance on PASCAL VOC 2012 semantic
segmentation with a simple approach. Code is available at
https://github.com/weiliu89/caffe/tree/fcn .Comment: ICLR 2016 submissio
No Spare Parts: Sharing Part Detectors for Image Categorization
This work aims for image categorization using a representation of distinctive
parts. Different from existing part-based work, we argue that parts are
naturally shared between image categories and should be modeled as such. We
motivate our approach with a quantitative and qualitative analysis by
backtracking where selected parts come from. Our analysis shows that in
addition to the category parts defining the class, the parts coming from the
background context and parts from other image categories improve categorization
performance. Part selection should not be done separately for each category,
but instead be shared and optimized over all categories. To incorporate part
sharing between categories, we present an algorithm based on AdaBoost to
jointly optimize part sharing and selection, as well as fusion with the global
image representation. We achieve results competitive to the state-of-the-art on
object, scene, and action categories, further improving over deep convolutional
neural networks
- âŠ