Iterative Low-Pass Filtering for Estimation of the Background in Fiber Diffraction Patterns

Disorientation of particles in fibrous specimens results in diffraction patterns in which the layer-line intensity is arced about the center, causing layer lines to overlap at larger radii and, as a consequence, making correction of the background problematic. Taking advantage of the fact that the background is typically made up of spatial frequencies that are substantially lower than those constituting the diffracted intensities, estimates of background in fiber diffraction patterns were made by applying an iterative low-pass filter to the diffraction data. This procedure has been applied to X-ray fiber diffraction patterns from filamentous bacteriophages to calculate the intensities along layer lines as well as to correct for the background.