ADAPTIVE FOURIER-FILTERING TECHNIQUE FOR QUANTITATIVE-EVALUATION OF HIGH-RESOLUTION ELECTRON-MICROGRAPHS OF INTERFACES

High-resolution electron micrographs of interface lattice images have been digitized, followed by a processing technique utilizing a spatial frequency filter. The filter possesses two special features: Firstly, the filter mask is generated automatically by the processing program using the rotation average of the image spectrum as a reference. Secondly, the signal-to-noise ratio of the filtered image is optimized by using anisotropic Bragg windows with a shape adapted to the spectrum of interfaces. The improvements of this adaptive filter compared to conventional Fourier filters are demonstrated. Possible artefacts and limitations are discussed.