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Blur Unblurred—A Mini Tutorial
Optical blur from defocus is quite frequently considered as equivalent to low-pass filtering. Yet that belief, although not entirely wrong, is inaccurate. Here, we wish to disentangle the concepts of dioptric blur, caused by myopia or mis-accommodation, from blur due to low-pass filtering when convo...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
SAGE Publications
2018
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5946648/ https://www.ncbi.nlm.nih.gov/pubmed/29770182 http://dx.doi.org/10.1177/2041669518765850 |
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author | Strasburger, Hans Bach, Michael Heinrich, Sven P. |
author_facet | Strasburger, Hans Bach, Michael Heinrich, Sven P. |
author_sort | Strasburger, Hans |
collection | PubMed |
description | Optical blur from defocus is quite frequently considered as equivalent to low-pass filtering. Yet that belief, although not entirely wrong, is inaccurate. Here, we wish to disentangle the concepts of dioptric blur, caused by myopia or mis-accommodation, from blur due to low-pass filtering when convolving with a Gaussian kernel. Perhaps surprisingly—if well known in optometry—the representation of a blur kernel (or point-spread function) for dioptric blur is, to a good approximation and disregarding diffraction, simply a cylinder. Its projection onto the retina is classically referred to as a blur circle, the diameter of which can easily be deduced from a light-ray model. We further give the derivation of the relationship between the blur-disk’s diameter and the extent of blur in diopters, as well as the diameter’s relation to the near or far point, and finally its relationship to visual acuity. |
format | Online Article Text |
id | pubmed-5946648 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | SAGE Publications |
record_format | MEDLINE/PubMed |
spelling | pubmed-59466482018-05-16 Blur Unblurred—A Mini Tutorial Strasburger, Hans Bach, Michael Heinrich, Sven P. Iperception Article Optical blur from defocus is quite frequently considered as equivalent to low-pass filtering. Yet that belief, although not entirely wrong, is inaccurate. Here, we wish to disentangle the concepts of dioptric blur, caused by myopia or mis-accommodation, from blur due to low-pass filtering when convolving with a Gaussian kernel. Perhaps surprisingly—if well known in optometry—the representation of a blur kernel (or point-spread function) for dioptric blur is, to a good approximation and disregarding diffraction, simply a cylinder. Its projection onto the retina is classically referred to as a blur circle, the diameter of which can easily be deduced from a light-ray model. We further give the derivation of the relationship between the blur-disk’s diameter and the extent of blur in diopters, as well as the diameter’s relation to the near or far point, and finally its relationship to visual acuity. SAGE Publications 2018-04-18 /pmc/articles/PMC5946648/ /pubmed/29770182 http://dx.doi.org/10.1177/2041669518765850 Text en © The Author(s) 2018 http://creativecommons.org/licenses/by/4.0/ Creative Commons CC-BY: This article is distributed under the terms of the Creative Commons Attribution 4.0 License (http://www.creativecommons.org/licenses/by/4.0/) which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage). |
spellingShingle | Article Strasburger, Hans Bach, Michael Heinrich, Sven P. Blur Unblurred—A Mini Tutorial |
title | Blur Unblurred—A Mini Tutorial |
title_full | Blur Unblurred—A Mini Tutorial |
title_fullStr | Blur Unblurred—A Mini Tutorial |
title_full_unstemmed | Blur Unblurred—A Mini Tutorial |
title_short | Blur Unblurred—A Mini Tutorial |
title_sort | blur unblurred—a mini tutorial |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5946648/ https://www.ncbi.nlm.nih.gov/pubmed/29770182 http://dx.doi.org/10.1177/2041669518765850 |
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