{{Short description|Photographic measurement of the distribution of grain sizes in a material}} {{Granulometry}}
'''Optical granulometry''' is the process of measuring the different grain sizes in a granular material,<ref>[http://www.eionet.europa.eu/gemet/concept?langcode=en&cp=11809 Definition of granularity] {{Webarchive|url=https://web.archive.org/web/20160304072401/http://www.eionet.europa.eu/gemet/concept?langcode=en&cp=11809 |date=2016-03-04 }} at GEMET</ref> based on a photograph. Technology has been created to analyze a photograph and create statistics based on what the picture portrays. This information is vital in maintaining machinery in various trades worldwide. Mining companies can use optical granulometry to analyze inactive or moving rock to quantify the size of these fragments.<ref>(Franklin and Katsabanis 1996), page 68</ref> Forestry companies can zero in on wood chip sizes without stopping the production process, and minimize sizing errors.<ref>(Franklin and Katsabanis 1996), page 47</ref>
With more photoanalysis technologies being produced, mining companies have shown an increased interest in these types of systems because of their ability to maintain efficiency throughout the mining process.<ref>(Franklin and Katsabanis 1996), page 258</ref> Companies are saving millions of dollars annually because of this new technology, and are cutting back on maintenance costs on equipment.{{Citation needed|date=August 2008}}
In order for optical granulometry to be completely successful, an accurate photo must be taken – under sufficient lighting, and using proper{{Clarify|date=October 2009}} technology – to obtain quantified results.<ref>(Franklin and Katsabanis 1996), page 115</ref> If these requirements are met, an image analysis system can be implemented.
==The process==
Software uses four basic steps in determining the average size of material:
thumb|300px|left|'''Step 1:''' Taking a photo- A sample of the material you would like to measure
thumb|300px|none|'''Step 2:''' Edge Detection- By completing an edge detection process, the software can determine the various sizes of material in the photo
thumb|300px|left|'''Step 3:''' Virtual Sieve- The length to width ratio is measured in this step of the process. The individual particle sizes are measured instantly.
thumb|300px|none|'''Step 4:''' Graphical Output- In this step, statistical data and size distribution is plotted on an easy-to-read form for operators. {{-}} See the Wikipedia article on Photoanalysis to see how mining, forestry and agricultural companies are using this technology to improve quality control techniques.
==Smartphone-based, segmentation-free estimation of grain size distribution== Recently, a methodology has emerged by which soil grain size distribution can be inferred from optical images acquired with commodity smartphones by training convolutional neural networks to predict parameters of the distribution curve directly from the image, without explicit image segmentation <ref>(Soranzo 2025)</ref>. In this approach, a standardized image of a soil surface is captured under controlled conditions, preprocessed to reduce device-specific variability, and passed to a regression model that outputs the parameters of a cumulative distribution function e.g., a two-parameter Weibull curve. The resulting distribution can be used to derive geotechnical descriptors and class boundaries.
== See also == * Particle-size distribution * Grain size * Granulometry (morphology)
==Notes==
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==References==
* <cite id=franklin96>''Measurement of Blast Fragmentation: Proceedings of a Workshop Held Parallel With Fragblast-5'', Montreal, 26–29 August 1996, by John A. Franklin, Takis Katsabanis, Published by Taylor & Francis, 1996, {{ISBN|90-5410-845-2}}</cite> * <cite id=Soranzo2025>''Convolutional neural network prediction of the particle size distribution of soil from close-range images'', Enrico Soranzo, Carlotta Guardiani, Wei Wu, "Soils and Foundations" 65(1) (2025), {{doi|10.1016/j.sandf.2025.101575}}, [https://doi.org/10.1016/j.sandf.2025.101575 DOI]</cite>
==External links== *[https://web.archive.org/web/20110715002658/http://online-image-analysis.com/web/main/particle-size-analysis Free Web Application for Particle and Grain Analysis]
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Category:Mining techniques Category:Image processing Category:Granulometric analyses