MRCZ meta-compressed image file-format library

pip install mrcz==0.5.6


Python MRCZ meta-compressed file-format module

mrcz is a package designed to supplement the venerable MRC image file format with a highly efficient compressed variant, using the blosc meta-compressor library to shrink files on disk and greatly accelerate file input/output for the era of "Big Data" in electron and optical microscopy.

Python versions 2.7, 3.4-3.6 are supported.

mrcz is currently considered to be a beta development state.

mrcz is released under the BSD 3-clause license.


A scientific Python installation (such as Anaconda, WinPython, or Canopy) is advised. After installation of your Python environment, from a command prompt type:

pip install mrcz

mrcz has the following dependencies:

  • numpy
  • blosc (optionally, but highly recommended)

Feature List

  • Import: DM4, MRC, MRCZ formats
  • Export: MRC, MRCZ formats
  • Compress and bit-shuffle image stacks and volumes with blosc meta-compressor
  • Asynchronous read and write operations.
  • Support in the hyperspy electron microscopy package.


Documentation is hosted at


See AUTHORS.txt.


  • R.A. McLeod, R. Diogo-Righetto, A. Stewart, H. Stahlberg, "MRCZ – A file format for cryo-TEM data with fast compression," Journal of Structural Biology, 201 (3) (March 2018): 252-267,
  • A. Cheng et al., "MRC2014: Extensions to the MRC format header for electron cryo-microscopy and tomography", Journal of Structural Biology 192(2): 146-150, November 2015,
  • V. Haenel, "Bloscpack: a compressed lightweight serialization format for numerical data", arXiv:1404.6383