Figure 3.

Segmentation maps of the MALDI-imaging dataset. Optical image (A) and segmentation maps (B-F) of the dataset from Figure 2 but with 80 μm spatial resolution. B. Straightforward k-means clustering of spectra. C. Hierarchical clustering (Euclidean distance, complete linkage) after PCA-reduction of spectra to 70% explained variance. D. Clustering after edge-preserving image denoising; moderate denoising, reprinted from [30] with permission from American Chemical Society. E-F. Efficient spatially-aware clustering, moderate size of data-adaptive neighborhood (E) and large size of non-adaptive neighborhood (F), reprinted from [52] with permission from Elsevier.