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. 2015 Mar 24;48(Pt 2):510-519.
doi: 10.1107/S1600576715004306. eCollection 2015 Apr 1.

The fast azimuthal integration Python library: pyFAI

Giannis Ashiotis  1 , Aurore Deschildre  1 , Zubair Nawaz  2 , Jonathan P Wright  1 , Dimitrios Karkoulis  1 , Frédéric Emmanuel Picca  3 , Jérôme Kieffer  1
Affiliations

The fast azimuthal integration Python library: pyFAI

Giannis Ashiotis et al. J Appl Crystallogr. .

Abstract

pyFAI is an open-source software package designed to perform azimuthal integration and, correspondingly, two-dimensional regrouping on area-detector frames for small- and wide-angle X-ray scattering experiments. It is written in Python (with binary submodules for improved performance), a language widely accepted and used by the scientific community today, which enables users to easily incorporate the pyFAI library into their processing pipeline. This article focuses on recent work, especially the ease of calibration, its accuracy and the execution speed for integration.

Keywords: GPU programming; Python; computer programs; data reduction; geometry calibration; image analysis; powder diffraction; small-angle X-ray scattering.

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Figures

Figure 1
Figure 1
The geometry used by pyFAI is inspired by SPD (Boesecke, 2007 ▶).
Figure 2
Figure 2
The pyFAI calibration window: manual peak picking and ring assignment can be performed though it. The data correspond to a lanthanum hexaboride (LaBformula image) calibrant on the Cristal beamline at Synchrotron Soleil taken at 18.57 keV on an Xpad S540 flat pixel detector tilted vertically by about 15°. This detector presents large (vertical) gaps between modules, explaining the incomplete arcs of rings a, b and d. Extracted control points are marked with dots, one colour per group (assigned to a letter), and the fitted iso-formula image contours are overlaid as dashed lines (red, orange and yellow coloured). The iso-formula image contour plot is not smooth because of gaps in the detector, explaining the incompleteness of some rings.
Figure 3
Figure 3
Contribution to a powder diffraction pattern from a single pixel, showcasing the different pixel-splitting algorithms. pyFAI implementations are compared with the corresponding FIT2D algorithm.
Figure 4
Figure 4
Graphical interface for performing azimuthal integration on a set of images.
Figure 5
Figure 5
Automatic removal of the amorphous signal (ice ring) from Bragg peaks in a protein crystallography experiment (data from beamline ID23-2 at the ESRF).
Figure 6
Figure 6
Comparison between the various pyFAI algorithms performing azimuthal integration.
See this image and copyright information in PMC

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