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Wang et al. Microstructures 2023;3:2023036 Microstructures
DOI: 10.20517/microstructures.2023.27

Research Article Open Access

Improving orientation mapping by enhancing the

diffraction signal using Auto-CLAHE in precession
electron diffraction data

Ainiu L. Wang, Marcus H. Hansen, Yi-Cheng Lai, Jiaqi Dong, Kelvin Y. Xie

Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, USA.
Correspondence to: Prof. Kelvin Y. Xie, Department of Materials Science and Engineering, Texas A&M University, 575 Ross St.,
College Station, TX 77843, USA. E-mail: kelvin_xie@tamu.edu

How to cite this article: Wang AL, Hansen MH, Lai YC, Dong J, Xie KY. Improving orientation mapping by enhancing the
diffraction signal using Auto-CLAHE in precession electron diffraction data. Microstructures 2023;3:2023034. https://
dx.doi.org/10. 20517/microstructures.2023.27

Received: 28 May 2023 First Decision: 7 Aug 2023 Revised: 7 Aug 2023 Accepted: 31 August 2023 Published: 7 Oct 2023

Academic Editor: Lin Gu Copy Editor: Fangyuan Liu Production Editor: Fangyuan Liu

Abstract
Precession electron diffraction (PED) is a powerful technique for revealing the crystallographic orientation of
samples at the nanoscale. However, the quality of orientation indexing is strongly influenced by the quality of
diffraction patterns. In this study, we have developed a novel algorithm called Auto-CLAHE (automatic contrast-
limited adaptive histogram equalization), which automatically enhances low-intensity diffraction pattern signals
using contrast-limited adaptive histogram equalization (CLAHE). The degree of enhancement is dynamically
adjusted based on the overall intensity of the diffraction pattern, with greater enhancement applied to patterns
with fewer spots (i.e., away from zone axes) and little or no enhancement applied to patterns with many spots (i.e.,
at a zone axis). By improving the visibility of low-intensity diffraction spots, Auto-CLAHE significantly improves the
template matching between experimentally acquired and simulated diffraction patterns, leading to orientation
maps with dramatically higher quality and lower noise. We anticipate that Auto-CLAHE provides an efficient and
practical solution for preprocessing PED data, enabling higher-quality crystal orientation mapping to be routinely
obtained.

Keywords: Precession electron diffraction (PED), orientation mapping, contrast-limited adaptive histogram
equalization (CLAHE), magnesium, nanoindentation

© The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0
International License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, sharing,
adaptation, distribution and reproduction in any medium or format, for any purpose, even commercially, as
long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and
indicate if changes were made.

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