40 research outputs found
Higher-order image statistics for unsupervised, information-theoretic, adaptive, image filtering
technical reportThe restoration of images is an important and widely studied problem in computer vision and image processing. Various image filtering strategies have been effective, but invariably make strong assumptions about the properties of the signal and/or degradation. Therefore, these methods typically lack the generality to be easily applied to new applications or diverse image collections. This paper describes a novel unsupervised, informationtheoretic, adaptive filter (UINTA) that improves the predictability of pixel intensities from their neighborhoods by decreasing the joint entropy between them. Thus UINTA automatically discovers the statistical properties of the signal and can thereby restore a wide spectrum of images and applications. This paper describes the formulation required to minimize the joint entropy measure, presents several important practical considerations in estimating image-region statistics, and then presents results on both real and synthetic data
Nonparametric neighborhood statistics for MRI denoising
technical reportThis paper presents a novel method for denoising MR images that relies on an optimal estimation, combining a likelihood model with an adaptive image prior. The method models images as random fields and exploits the properties of independent Rician noise to learn the higher-order statistics of image neighborhoods from corrupted input data. It uses these statistics as priors within a Bayesian denoising framework. This paper presents an information-theoretic method for characterizing neighborhood structure using nonparametric density estimation. The formulation generalizes easily to simultaneous denoising of multimodal MRI, exploiting the relationships between modalities to further enhance performance. The method, relying on the information content of input data for noise estimation and setting important parameters, does not require significant parameter tuning. Qualitative and quantitative results on real, simulated, and multimodal data, including comparisons with other approaches, demonstrate the effectiveness of the method
Image denoising with unsupervised, information-theoretic, adaptive filtering
technical reportThe problem of denoising images is one of the most important and widely studied problems in image processing and computer vision. Various image filtering strategies based on linear systems, statistics, information theory, and variational calculus, have been effective, but invariably make strong assumptions about the properties of the signal and/or noise. Therefore, they lack the generality to be easily applied to new applications or diverse image collections. This paper describes a novel unsupervised, information-theoretic, adaptive filter (UINTA) that improves the predictability of pixel intensities from their neighborhoods by decreasing the joint entropy between them. In this way UINTA automatically discovers the statistical properties of the signal and can thereby reduce noise in a wide spectrum of images and applications. The paper describes the formulation required to minimize the joint entropy measure, presents several important practical considerations in estimating image-region statistics, and then presents a series of results and comparisons on both real and synthetic data
Nonparametric statistics of image neighborhoods for unsupervised texture segmentation
technical reportIn this paper, we present a novel approach to unsupervised texture segmentation that is based on a very general statistical model of image neighborhoods. We treat image neighborhoods as samples from an underlying, high-dimensional probability density function (PDF). We obtain an optimal segmentation via the minimization of an entropy-based metric on the neighborhood PDFs conditioned on the classification. Unlike previous work in this area, we model image neighborhoods directly without preprocessing or the construction of intermediate features. We represent the underlying PDFs nonparametrically, using Parzen windowing, thus enabling the method to model a wide variety of textures. The entropy minimization drives a level-set evolution that provides a degree of spatial homogeneity. We show that the proposed approach easily generalizes, from the two-class case, to an arbitrary number of regions by incorporating an efficient multi-phase level-set framework. This paper presents results on synthetic and real images from the literature, including segmentations of electron microscopy images of cellular structures
Hierarchical Graphical Models for Multigroup Shape Analysis using Expectation Maximization with Sampling in Kendall's Shape Space
This paper proposes a novel framework for multi-group shape analysis relying
on a hierarchical graphical statistical model on shapes within a population.The
framework represents individual shapes as point setsmodulo translation,
rotation, and scale, following the notion in Kendall shape space.While
individual shapes are derived from their group shape model, each group shape
model is derived from a single population shape model. The hierarchical model
follows the natural organization of population data and the top level in the
hierarchy provides a common frame of reference for multigroup shape analysis,
e.g. classification and hypothesis testing. Unlike typical shape-modeling
approaches, the proposed model is a generative model that defines a joint
distribution of object-boundary data and the shape-model variables.
Furthermore, it naturally enforces optimal correspondences during the process
of model fitting and thereby subsumes the so-called correspondence problem. The
proposed inference scheme employs an expectation maximization (EM) algorithm
that treats the individual and group shape variables as hidden random variables
and integrates them out before estimating the parameters (population mean and
variance and the group variances). The underpinning of the EM algorithm is the
sampling of pointsets, in Kendall shape space, from their posterior
distribution, for which we exploit a highly-efficient scheme based on
Hamiltonian Monte Carlo simulation. Experiments in this paper use the fitted
hierarchical model to perform (1) hypothesis testing for comparison between
pairs of groups using permutation testing and (2) classification for image
retrieval. The paper validates the proposed framework on simulated data and
demonstrates results on real data.Comment: 9 pages, 7 figures, International Conference on Machine Learning 201
FUTURE-AI: International consensus guideline for trustworthy and deployable artificial intelligence in healthcare
Despite major advances in artificial intelligence (AI) for medicine and
healthcare, the deployment and adoption of AI technologies remain limited in
real-world clinical practice. In recent years, concerns have been raised about
the technical, clinical, ethical and legal risks associated with medical AI. To
increase real world adoption, it is essential that medical AI tools are trusted
and accepted by patients, clinicians, health organisations and authorities.
This work describes the FUTURE-AI guideline as the first international
consensus framework for guiding the development and deployment of trustworthy
AI tools in healthcare. The FUTURE-AI consortium was founded in 2021 and
currently comprises 118 inter-disciplinary experts from 51 countries
representing all continents, including AI scientists, clinicians, ethicists,
and social scientists. Over a two-year period, the consortium defined guiding
principles and best practices for trustworthy AI through an iterative process
comprising an in-depth literature review, a modified Delphi survey, and online
consensus meetings. The FUTURE-AI framework was established based on 6 guiding
principles for trustworthy AI in healthcare, i.e. Fairness, Universality,
Traceability, Usability, Robustness and Explainability. Through consensus, a
set of 28 best practices were defined, addressing technical, clinical, legal
and socio-ethical dimensions. The recommendations cover the entire lifecycle of
medical AI, from design, development and validation to regulation, deployment,
and monitoring. FUTURE-AI is a risk-informed, assumption-free guideline which
provides a structured approach for constructing medical AI tools that will be
trusted, deployed and adopted in real-world practice. Researchers are
encouraged to take the recommendations into account in proof-of-concept stages
to facilitate future translation towards clinical practice of medical AI