3.7. Classification and use of image data

H. J. Bernstein

Abstract

This chapter describes the categories and organization of data items used in the representation of image data. The classification applies to both Crystallographic Binary File (CBF) and Image-supporting Crystallographic Information File (imgCIF) representations. The primary motivation for introducing the items defined in the CBF/imgCIF dictionary is to extend the mmCIF dictionary (Chapter 3.6) for the storage of synchrotron diffraction images. However, these items have the potential for use in other fields that require binary image data, including journal publishing, creation of web pages or the production of movies.

Data categories in the CBF/imgCIF dictionary support one-, two- and three-dimensional array detectors that output data organized by time and/or wavelength. Three major groups of categories are defined: ARRAY_DATA describes the image data themselves; AXIS is used to identify unambiguously the laboratory coordinate system; and DIFFRN introduces new terms that characterize the experimental apparatus and measurements.

Links

Figures

The printed figures in this chapter are reproduced in colour here.

	Fig. 3.7.2.1. ARRAY_STRUCTURE_LIST specification of linearly organized image elements.
	Fig. 3.7.2.2. ARRAY_STRUCTURE_LIST specification of 'constant-angle' image elements in a cylindrical scan. The angular and radial axes are independent. Note that outer-zone image elements are further apart, centre-to-centre, than inner-zone image elements.
	Fig. 3.7.2.3. ARRAY_STRUCTURE_LIST specification of 'constant-velocity' image elements in a cylindrical scan. The angular and radial axes are coupled. Note that outer-zone image elements are the same linear distance apart, centre-to-centre, as the inner-zone image elements.
	Fig. 3.7.3.1. AXIS laboratory coordinate system. The origin is centred in the specimen.

Dictionaries

The following CIF dictionary is referenced in this chapter:

image supporting CIF dictionary

Supporting materials

Example files that may be of use in association with this chapter are found on the following page:

Example image file in MAR format and different CBF and imgCIF representations

References

Aho, A. V., Hopcroft, J. E. & Ullman, J. D. (1987). Data structures and algorithms. Reading, MA: Addison-Wesley.

Leslie, A. G. W. & Powell, H. (2003). MOSFLM V6.11. http://www.dl.ac.uk/CCP/CCP4/dist/x-windows/Mosflm.