arXiv subjects

Charles Wood

Publications and source records attributed to Charles Wood.

5 recordsLinked to original sources

arXiv2026

Information Theory: An X-ray Microscopy Perspective

X-ray microscopy (XRM) is commonly used to obtain three-dimensional information on internal microstructure, but the imaging pipeline introduces noise, redundancy and information loss at multiple stages. This paper treats the XRM workflow as an information-processing system acting on a finite information budget. Using entropy, mutual information and Kullback-Leibler divergence, we quantify how acquisition, denoising, alignment, sparse-angle sampling, dose variation and reconstruction reshape the statistical structure of projection data and reconstructed volumes. Case studies based on the Walnut 1 dataset illustrate how these processes redistribute information and impose bottlenecks. We summarise the workflow using a unified information budget and show that mutual information provides a reconstruction-agnostic indicator of fidelity, supporting quantitative comparison and optimisation of XRM protocols, particularly under low-dose or time-constrained conditions

eess.IV↗

arXiv2026

Constraint-Induced Effective Mass in Massless Field Propagation

Constrained propagation of massless fields is ubiquitous in physical systems, arising from boundaries, material structure, or other restrictions on admissible modes. This paper shows that such constraints generically induce mass-like terms in the effective dispersion relation, without modifying the underlying field equations or introducing new degrees of freedom. Working at an abstract level, constraints are represented as linear operators acting on the field's mode space. Restriction of the admissible mode manifold produces a spectral gap whose magnitude is set by the smallest non-zero eigenvalue of an associated positive semidefinite operator. This gap may be identified with an effective mass parameter, yielding a Proca-like dispersion relation in the long-wavelength limit. The resulting Mass Induction Principle identifies rank reduction of the accessible mode space as the structural mechanism responsible for effective mass generation in constrained massless fields. Familiar systems such as plasmas, superconductors, and periodic media realise this structure as special cases, without introducing new dynamics. The analysis is deliberately dispersion-level and non-phenomenological: it does not assert a field-theoretic mass term, does not address vacuum propagation, and does not make claims about bounds on intrinsic particle masses.

physics.gen-ph↗

arXiv2026

Information Geometry of Imaging Operators

Imaging systems are represented as linear operators, and their singular value spectra describe the structure recoverable at the operator level. Building on an operator-based information-theoretic framework, this paper introduces a minimal geometric structure induced by the normalised singular spectra of imaging operators. By identifying spectral equivalence classes with points on a probability simplex, and equipping this space with the Fisher--Rao information metric, a well-defined Riemannian geometry can be obtained that is invariant under unitary transformations and global rescaling. The resulting geometry admits closed-form expressions for distances and geodesics, and has constant positive curvature. Under explicit restrictions, composition enforces boundary faces through rank constraints and, in an aligned model with stated idealisations, induces a non-linear re-weighting of spectral states. Fisher--Rao distances are preserved only in the spectrally uniform case. The construction is abstract and operator-level, introducing no optimisation principles, stochastic models, or modality-specific assumptions. It is intended to provide a fixed geometric background for subsequent analysis of information flow and constraints in imaging pipelines.

cs.IT↗

arXiv2025

Operator-Based Information Theory for Imaging: Entropy, Capacity, and Irreversibility in Physical Measurement Systems

Imaging systems are commonly described using resolution, contrast, and signal-to-noise ratio, but these quantities do not provide a general account of how physical transformations affect the flow of information. This paper introduces an operator-based formulation of information theory for imaging. The approach models the imaging chain as a composition of bounded operators acting on functions, and characterises information redistribution using the spectral properties of these operators. Three measures are developed. Operator entropy quantifies how an operator distributes energy across its singular spectrum. Operator information capacity describes the number of modes that remain recoverable above a noise-dependent threshold. An irreversibility index measures the information lost through suppression or elimination of modes and captures the accumulation of information loss under operator composition. The framework applies to linear, nonlinear, and stochastic operators and does not depend on the specific imaging modality. Analytical examples show how attenuation, blur, and sampling affect entropy, capacity, and irreversibility in different ways. The results provide a general structure for analysing the physical limits of imaging and form the basis for subsequent work on information geometry, spatiotemporal budgets, nonlinear channels, and reconstruction algorithms.

eess.IV↗

arXiv2016

Geomorphologic Mapping of Titan's Polar Terrains: Constraining Surface Processes and Landscape Evolution

We present a geomorphologic map of Titan's polar terrains. The map was generated from a combination of Cassini Synthetic Aperture Radar (SAR) and Imaging Science Subsystem imaging products, as well as altimetry, SARTopo and radargrammetry topographic datasets. In combining imagery with topographic data, our geomorphologic map reveals a stratigraphic sequence from which we infer process interactions between units. In mapping both polar regions with the same geomorphologic units, we conclude that processes that formed the terrains of the north polar region also acted to form the landscape we observe at the south. Uniform, SAR-dark plains are interpreted as sedimentary deposits, and are bounded by moderately dissected uplands. These plains contain the highest density of filled and empty lake depressions, and canyons. These units unconformably overlay a basement rock that outcrops as mountains and SAR-bright dissected terrains at various elevations across both poles. All these units are then superposed by surficial units that slope towards the seas, suggestive of subsequent overland transport of sediment. From estimates of the depths of the embedded empty depressions and canyons that drain into the seas, the SAR-dark plains must be >600 m thick in places, though the thickness may vary across the poles. At the lowest elevations of each polar region, there are large seas, which are currently liquid methane/ethane filled at the north and empty at the south. The large plains deposits and the surrounding hillslopes may represent remnant landforms that are a result of previously vast polar oceans, where larger liquid bodies may have allowed for a sustained accumulation of soluble and insoluble sediments, potentially forming layered sedimentary deposits. Coupled with vertical crustal movements, the resulting layers would be of varying solubilities and erosional resistances.

astro-ph.EP↗