Transformation using an approximating function to capture important patterns in data, while removing noise or other fine-scale structures.
Example: Smoothing functions like moving average and Savitzky–Golay.
Source:
PAC, 2016, 88, 407. 'Vocabulary of concepts and terms in chemometrics (IUPAC Recommendations 2016)' on page 412 (https://doi.org/10.1515/pac-2015-0605)