Distributed Automatic Differentiation for Ptychography

Youssef S.G. Nashed, Tom Peterka, Junjing Deng, Chris Jacobsen

Research output: Contribution to journalConference articlepeer-review

23 Scopus citations


Synchrotron radiation light source facilities are leading the way to ultrahigh resolution X-ray imaging. High resolution imaging is essential to understanding the fundamental structure and interaction of materials at the smallest length scale possible. Diffraction based methods achieve nanoscale imaging by replacing traditional objective lenses by pixelated area detectors and computational image reconstruction. Among these methods, ptychography is quickly becoming the standard for sub-30 nanometer imaging of extended samples, but at the expense of increasingly high data rates and volumes. This paper presents a new distributed algorithm for solving the ptychographic image reconstruction problem based on automatic differentiation. Input datasets are subdivided between multiple graphics processing units (GPUs); each subset of the problem is then solved either entirely independent of other subsets (asynchronously) or through sharing gradient information with other GPUs (synchronously). The algorithm was evaluated on simulated and real data acquired at the Advanced Photon Source, scaling up to 192 GPUs. The synchronous variant of our method outperformed an existing multi-GPU implementation in terms of accuracy while running at a comparable execution time.

Original languageEnglish (US)
Pages (from-to)404-414
Number of pages11
JournalProcedia Computer Science
StatePublished - 2017
EventInternational Conference on Computational Science ICCS 2017 - Zurich, Switzerland
Duration: Jun 12 2017Jun 14 2017


  • X-ray scattering
  • distributed algorithms
  • gradient methods
  • image reconstruction
  • inverse problems

ASJC Scopus subject areas

  • Computer Science(all)


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