Noise Reduction of Electron Holography Phase Maps with Non-Local-Mean Wavelet Analysis

A non-local-means algorithm with non-local averaging is used to reduce noise in an electron holography phase map. The noise level is evaluated through wavelet analysis. The method is shown to be effective in reducing noise in the map while preserving both the spatial resolution and underlying map information. Because of the significant noise reduction, the processed phase map is easier to understand and can produce an internal electric field map with a derivative of the phase map.