Posit AI Blog: Pre-processing layers in keras: What they are and how to use them

Data pre-processing: What you do to the data before feeding it to the model. Where, exactly, should pre-processing stop, and the model begin? Are steps like normalization, or various numerical transforms, part of the model, or the pre-processing? In sum, the line between what is pre-processing and what is modeling has always, at the edges, felt somewhat fluid. In this situation, the advent of keras pre-processing layers changes a long-familiar picture.