8,515 research outputs found
Graph Spectral Image Processing
Recent advent of graph signal processing (GSP) has spurred intensive studies
of signals that live naturally on irregular data kernels described by graphs
(e.g., social networks, wireless sensor networks). Though a digital image
contains pixels that reside on a regularly sampled 2D grid, if one can design
an appropriate underlying graph connecting pixels with weights that reflect the
image structure, then one can interpret the image (or image patch) as a signal
on a graph, and apply GSP tools for processing and analysis of the signal in
graph spectral domain. In this article, we overview recent graph spectral
techniques in GSP specifically for image / video processing. The topics covered
include image compression, image restoration, image filtering and image
segmentation
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Modern Statistical/Machine Learning Techniques for Bio/Neuro-imaging Applications
Developments in modern bio-imaging techniques have allowed the routine collection of a vast amount of data from various techniques. The challenges lie in how to build accurate and efficient models to draw conclusions from the data and facilitate scientific discoveries. Fortunately, recent advances in statistics, machine learning, and deep learning provide valuable tools. This thesis describes some of our efforts to build scalable Bayesian models for four bio-imaging applications: (1) Stochastic Optical Reconstruction Microscopy (STORM) Imaging, (2) particle tracking, (3) voltage smoothing, (4) detect color-labeled neurons in c elegans and assign identity to the detections
Emergence of charge order in a staggered loop-current phase of cuprate high-temperature superconductors
We study the emergence of charge ordered phases within a pi-loop current
(piLC) model for the pseudogap based on a three-band model for underdoped
cuprate superconductors. Loop currents and charge ordering are driven by
distinct components of the short-range Coulomb interactions: loop currents
result from the repulsion between nearest-neighbor copper and oxygen orbitals,
while charge order results from repulsion between neighboring oxygen orbitals.
We find that the leading piLC phase has an antiferromagnetic pattern similar to
previously discovered staggered flux phases, and that it emerges abruptly at
hole dopings p below the van Hove filling. Subsequent charge ordering
tendencies in the piLC phase reveal that diagonal d-charge density waves (dCDW)
are suppressed by the loop currents while axial order competes more weakly. In
some cases we find a wide temperature range below the loop-current transition,
over which the susceptibility towards an axial dCDW is large. In these cases,
short-range axial charge order may be induced by doping-related disorder. A
unique feature of the coexisting dCDW and piLC phases is the emergence of an
incommensurate modulation of the loop currents. If the dCDW is biaxial
(checkerboard) then the resulting incommensurate current pattern breaks all
mirror and time-reversal symmetries, thereby allowing for a polar Kerr effect
Semantic-Aware Dual Contrastive Learning for Multi-label Image Classification
Extracting image semantics effectively and assigning corresponding labels to
multiple objects or attributes for natural images is challenging due to the
complex scene contents and confusing label dependencies. Recent works have
focused on modeling label relationships with graph and understanding object
regions using class activation maps (CAM). However, these methods ignore the
complex intra- and inter-category relationships among specific semantic
features, and CAM is prone to generate noisy information. To this end, we
propose a novel semantic-aware dual contrastive learning framework that
incorporates sample-to-sample contrastive learning (SSCL) as well as
prototype-to-sample contrastive learning (PSCL). Specifically, we leverage
semantic-aware representation learning to extract category-related local
discriminative features and construct category prototypes. Then based on SSCL,
label-level visual representations of the same category are aggregated
together, and features belonging to distinct categories are separated.
Meanwhile, we construct a novel PSCL module to narrow the distance between
positive samples and category prototypes and push negative samples away from
the corresponding category prototypes. Finally, the discriminative label-level
features related to the image content are accurately captured by the joint
training of the above three parts. Experiments on five challenging large-scale
public datasets demonstrate that our proposed method is effective and
outperforms the state-of-the-art methods. Code and supplementary materials are
released on https://github.com/yu-gi-oh-leilei/SADCL.Comment: 8 pages, 6 figures, accepted by European Conference on Artificial
Intelligence (2023 ECAI
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