Representations of sources from the labelled subsample within the space defined by the first two principal components, with colours corresponding to cluster labels as listed in the legend. Left: representations from the pre-training stage are displayed, showing a dispersed distribution pattern. Additionally, a representative image from each cluster is provided to highlight the morphological structure within the distribution. Right: post fine-tuning representations are presented, demonstrating compact clustering according to the labels. Arrows are included to depict the evolution of selected clusters from the pre-training to the fine-tuning stage.