Enhancing Accuracy and Precision in Omni-Angle Edge-Based Modulation Transfer Function Measurements

The modulation transfer function (MTF) quantitatively describes the ability of an optical or imaging system to reproduce contrast at various spatial frequencies. The ISO 12233 edge-based method adopted diagonal MTF measurement for sampled imaging systems by analyzing the gradient of a slanted edge c...

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Main Author: Kenichiro Masaoka
Format: Article
Language:English
Published: IEEE 2025-01-01
Series:IEEE Access
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Online Access:https://ieeexplore.ieee.org/document/10847840/
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author Kenichiro Masaoka
author_facet Kenichiro Masaoka
author_sort Kenichiro Masaoka
collection DOAJ
description The modulation transfer function (MTF) quantitatively describes the ability of an optical or imaging system to reproduce contrast at various spatial frequencies. The ISO 12233 edge-based method adopted diagonal MTF measurement for sampled imaging systems by analyzing the gradient of a slanted edge captured by the system and estimating MTF as a function of spatial frequency perpendicular to the edge. Pixels in a region of interest (ROI) are projected into a quarter-pixel wide bin array on a horizontal or vertical axis, yielding a <inline-formula> <tex-math notation="LaTeX">$4\times $ </tex-math></inline-formula> oversampled edge spread function. However, the accuracy and precision of MTF estimates can degrade considerably at high spatial frequencies for certain edge angles because of the clustering of the projection paths at or around specific locations on the bin array axis. Thus, a novel edge-based method, Omni-sine, was proposed to overcome this limitation by optimizing a noninteger oversampling ratio based on the edge angle. The accuracy and precision of the proposed method were demonstrated through computer simulations using synthesized edge images and through actual measurements with a machine vision camera. Implementing the Omni-sine method does not affect the real-time nature of the edge-based measurement and facilitates MTF anisotropy measurements using multiple nonrectangular ROIs with slanted starburst charts.
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spelling doaj-art-1231a5a33b3e4ccbb2d9c68629c186ef2025-02-05T00:00:49ZengIEEEIEEE Access2169-35362025-01-0113207992080910.1109/ACCESS.2025.353211910847840Enhancing Accuracy and Precision in Omni-Angle Edge-Based Modulation Transfer Function MeasurementsKenichiro Masaoka0https://orcid.org/0000-0002-7977-3262NHK Foundation, Tokyo, JapanThe modulation transfer function (MTF) quantitatively describes the ability of an optical or imaging system to reproduce contrast at various spatial frequencies. The ISO 12233 edge-based method adopted diagonal MTF measurement for sampled imaging systems by analyzing the gradient of a slanted edge captured by the system and estimating MTF as a function of spatial frequency perpendicular to the edge. Pixels in a region of interest (ROI) are projected into a quarter-pixel wide bin array on a horizontal or vertical axis, yielding a <inline-formula> <tex-math notation="LaTeX">$4\times $ </tex-math></inline-formula> oversampled edge spread function. However, the accuracy and precision of MTF estimates can degrade considerably at high spatial frequencies for certain edge angles because of the clustering of the projection paths at or around specific locations on the bin array axis. Thus, a novel edge-based method, Omni-sine, was proposed to overcome this limitation by optimizing a noninteger oversampling ratio based on the edge angle. The accuracy and precision of the proposed method were demonstrated through computer simulations using synthesized edge images and through actual measurements with a machine vision camera. Implementing the Omni-sine method does not affect the real-time nature of the edge-based measurement and facilitates MTF anisotropy measurements using multiple nonrectangular ROIs with slanted starburst charts.https://ieeexplore.ieee.org/document/10847840/Anisotropymodulation transfer functionnoninteger oversamplingpixel spacingspatial resolution
spellingShingle Kenichiro Masaoka
Enhancing Accuracy and Precision in Omni-Angle Edge-Based Modulation Transfer Function Measurements
IEEE Access
Anisotropy
modulation transfer function
noninteger oversampling
pixel spacing
spatial resolution
title Enhancing Accuracy and Precision in Omni-Angle Edge-Based Modulation Transfer Function Measurements
title_full Enhancing Accuracy and Precision in Omni-Angle Edge-Based Modulation Transfer Function Measurements
title_fullStr Enhancing Accuracy and Precision in Omni-Angle Edge-Based Modulation Transfer Function Measurements
title_full_unstemmed Enhancing Accuracy and Precision in Omni-Angle Edge-Based Modulation Transfer Function Measurements
title_short Enhancing Accuracy and Precision in Omni-Angle Edge-Based Modulation Transfer Function Measurements
title_sort enhancing accuracy and precision in omni angle edge based modulation transfer function measurements
topic Anisotropy
modulation transfer function
noninteger oversampling
pixel spacing
spatial resolution
url https://ieeexplore.ieee.org/document/10847840/
work_keys_str_mv AT kenichiromasaoka enhancingaccuracyandprecisioninomniangleedgebasedmodulationtransferfunctionmeasurements