raw data letters

Raw Data Letters

A Raw Data Letter allows researchers to highlight aspects of their raw data that could be of interest to a wide range of researchers working in the biological, chemical, materials science or physics fields, from methods and software developers, to structural scientists interested in reanalysis, validation or review.

raw data archive publish


Raw data files

Of the variety of image formats, HDF5, CBF, SMV (ADSC) are the most popular and standardized. Where possible, any other formats should be converted to CBF before archiving. CBF logically separates into two standards: one for describing the image encoding, and one for the metadata.

Archiving raw data

As part of ensuring that raw data are Findable, Accessible, Interoperable and Re-usable (FAIR), raw data files should be deposited in open-access persistent archives that assign a Digital Object Identifier (DOI) to a data set (for example Zenodo). For raw image data, the recommended archive formats are: zip, tar+gzip, bzip2, xz, HDF5 (with standard compression filters).

Documenting metadata – imgCIF

Using tools that can read a collection of raw data files, a description of the associated metadata, including references to the locations of the raw data (binary) files, can be captured in plain text as an 'imgCIF'. An imgCIF file provides data in CIF format, which is both machine-readable and human-readable, with a comprehensive set of tags (defined in the imgCIF dictionary) for describing detector geometries and other experimental parameters, thus facilitating FAIR 're-usability'. The archived raw data, imgCIF metadata, and ultimately the published Raw Data Letter are all linked via DOIs.

Publishing raw data

A Word template for writing a Raw Data Letter is available here. Submission of the Raw Data Letter to IUCrData should be accompanied by the imgCIF describing the archived raw data. The submitted Raw Data Letter along with a checkCIF validation report will be subject to peer review before publication.


The editors of Raw Data Letters and the developers of the imgCIF creation and validation tools are very keen to work with authors to facilitate publication of their data. Please see the useful links listed on this page and in particular the editorial that announced IUCrData Raw Data Letters.