The "Crystallographic Binary File" (CBF) Format

A. Hammersley1 and R.M. Sweet2
1European Synchrotron Research Facility, and 2Biology Department, Brookhaven National Laboratory

The Crystallographic Binary File format initiative is intended to extend the concept of the CIF (Crystallographic Information File) format to the efficient transfer of multi-dimensional data, directly from imaging detectors to analysis programs. The "imgCIF" e-mail discussion group has been working closely with the IUCr COMCIFS committee to achieve eventual full IUCr endorsement, and a wide range of academic and industrial groups are involved.

Following extensive e-mail discussions, the major outline of the format was decided at a recent workshop at Brookhaven National Laboratory on 20th-22nd October 1997. Pseudo-ASCII header sections, using CIF dictionary items, will provide information to describe how both the experiments were performed and how the data were stored. Binary data sections will follow, containing large volumes of pixel (or voxel, etc.) data in well defined binary forms. Initially two types of loss-less data compression algorithms will be supported.

The format is sufficiently flexible to store complicated experiments which consist of multiple series of images, whilst being simple enough to store single images with no overhead compared to other detector formats. An application interface library is being written for "C", Fortran, and "C++" programs. The interface is written in ANSI-C and is to be highly portable. The source code will be freely available, and may be used or modified under the IUCr copyright conditions.

We will describe the status of the work, the rationale behind the format, and the initial supported data compression methods.

This work has been supported by the ESRF, the Office of Biological and Environmental Research of the U.S. Department of Energy, and others. The workshop sponsors: The Nonius Company, Area Detector Systems Corp., Reciprocal Space Ventures Association, MAR Research, and Bruker Analytical X-Ray Inc.

(modified 05-Nov-97 jw)