Optimizing an image analysis protocol for ocean particles in focused shadowgraph imaging systems

A variety of imaging systems are in use in oceanographic surveys, and the opto-mechanical configurations have become highly sophisticated. However, much less consideration has been given to the accurate reconstruction of imaging data. To improve reconstruction of particles captured by Focused Shadow...

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Main Authors: Huanqing Huang, Alexander B. Bochdansky
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-07-01
Series:Frontiers in Marine Science
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Online Access:https://www.frontiersin.org/articles/10.3389/fmars.2025.1539828/full
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author Huanqing Huang
Alexander B. Bochdansky
author_facet Huanqing Huang
Alexander B. Bochdansky
author_sort Huanqing Huang
collection DOAJ
description A variety of imaging systems are in use in oceanographic surveys, and the opto-mechanical configurations have become highly sophisticated. However, much less consideration has been given to the accurate reconstruction of imaging data. To improve reconstruction of particles captured by Focused Shadowgraph Imaging (FoSI)—a system that excels at visualizing low-optical-density objects, we developed a novel object detection algorithm to process images with a resolution of ~ 12 μm per pixel. Suggested improvements to conventional edge-detection methods are relatively simple and time-efficient, and more accurately render the sizes and shapes of small particles ranging from 24 to 500 μm. In addition, we introduce a gradient of neutral density filters as a part of the protocol serving to calibrate recorded gray levels and thus determine the absolute values of detection thresholds. Set to intermediate detection threshold levels, particle numbers were highly correlated with beam attenuation (cp) measured independently. The utility of our method was underscored by its ability to remove imperfections (dirt, scratches and uneven illumination), and by capturing the transparent particle features such as found in gelatinous plankton, marine snow and a portion of the oceanic gel phase.
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spelling doaj-art-5b9df17e810e4284a26f7c4f15d0d7c82025-07-16T20:30:59ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452025-07-011210.3389/fmars.2025.15398281539828Optimizing an image analysis protocol for ocean particles in focused shadowgraph imaging systemsHuanqing HuangAlexander B. BochdanskyA variety of imaging systems are in use in oceanographic surveys, and the opto-mechanical configurations have become highly sophisticated. However, much less consideration has been given to the accurate reconstruction of imaging data. To improve reconstruction of particles captured by Focused Shadowgraph Imaging (FoSI)—a system that excels at visualizing low-optical-density objects, we developed a novel object detection algorithm to process images with a resolution of ~ 12 μm per pixel. Suggested improvements to conventional edge-detection methods are relatively simple and time-efficient, and more accurately render the sizes and shapes of small particles ranging from 24 to 500 μm. In addition, we introduce a gradient of neutral density filters as a part of the protocol serving to calibrate recorded gray levels and thus determine the absolute values of detection thresholds. Set to intermediate detection threshold levels, particle numbers were highly correlated with beam attenuation (cp) measured independently. The utility of our method was underscored by its ability to remove imperfections (dirt, scratches and uneven illumination), and by capturing the transparent particle features such as found in gelatinous plankton, marine snow and a portion of the oceanic gel phase.https://www.frontiersin.org/articles/10.3389/fmars.2025.1539828/fulloptical oceanographyparticle imagingshadowgraphybinarizationedge-detectiongels
spellingShingle Huanqing Huang
Alexander B. Bochdansky
Optimizing an image analysis protocol for ocean particles in focused shadowgraph imaging systems
Frontiers in Marine Science
optical oceanography
particle imaging
shadowgraphy
binarization
edge-detection
gels
title Optimizing an image analysis protocol for ocean particles in focused shadowgraph imaging systems
title_full Optimizing an image analysis protocol for ocean particles in focused shadowgraph imaging systems
title_fullStr Optimizing an image analysis protocol for ocean particles in focused shadowgraph imaging systems
title_full_unstemmed Optimizing an image analysis protocol for ocean particles in focused shadowgraph imaging systems
title_short Optimizing an image analysis protocol for ocean particles in focused shadowgraph imaging systems
title_sort optimizing an image analysis protocol for ocean particles in focused shadowgraph imaging systems
topic optical oceanography
particle imaging
shadowgraphy
binarization
edge-detection
gels
url https://www.frontiersin.org/articles/10.3389/fmars.2025.1539828/full
work_keys_str_mv AT huanqinghuang optimizinganimageanalysisprotocolforoceanparticlesinfocusedshadowgraphimagingsystems
AT alexanderbbochdansky optimizinganimageanalysisprotocolforoceanparticlesinfocusedshadowgraphimagingsystems