Morphological erosion is a sliding-window minimum nonlinear Filter over a Signal. For each sample, the output is the minimum value within a kernel of width centered on that sample:
- Applied to a Power Spectrum, erosion carves out any spectral peak narrower than bins, leaving only broad structures. Used as the first step in Morphological Opening.
- This is a Stencil operation: each output depends only on a fixed neighborhood of surrounding inputs, with a nonlinear min reduction instead of a weighted sum.