SHARD Algorithm’s iterative pipeline. The first phase of SHARD (white boxes), involves a regularized spherical harmonic fit to the preprocessed diffusion data, which enables estimation of the standard deviation of the model fit across the brain (σ). The second phase (green boxes) uses iterative reweighted spherical harmonic fitting to identify and de-weight outliers on a voxelwise basis. Finally (red boxes), outliers are identified from the reweighted spherical harmonic fit, median filtered, and imputed with their model fit values. The resulting data can be used in subsequent HARDI model processing (black box).