Clustering optical signatures of passive layer formation before pitting is more nuanced than pit detection. Here, reflectivity changes are more homogeneous with a low signal-to-noise ratio, unlike the stark contrasts of pits, which require an algorithm that performs image segmentation on noisy time series of optical signatures. Collectively, examples from the literature and our prior work showcased that the simplest K-means can be sufficient, which was used herein as a basis to distinguish regions of PSZ.