3-DIMENSIONAL DISTORTION CORRECTION APPLIED TO TOMOGRAPHIC RECONSTRUCTIONS OF SECTIONED CRYSTALS

Unaveraged tomograms of embedded and sectioned insect flight muscle sh ow not only structural variation within the individual unit cells but also defects in the filament lattice such as lack of straightness of t he filaments and wrinkling of the sections. Adaptation of conventional 2D crystal image processing methods usually average out these structu ral variations and lattice defects thereby reducing the resolution and information content of the 3D reconstructions. We present here a comp utational method to correct the reconstructed 3D object for these dist ortions to make it suitable for further analysis. The correction is an extension of conventional 2D cross-correlation techniques applied to a 3D image. These procedures determine the unit cell positions of the distorted crystal and use a spline-fitting approach to calculate a map ping function from the observed positions that is subsequently used to reinterpolate the image onto a regular grid. The resulting reinterpol ated image is corrected for both filament straightening as well as sec tion wrinkling.