SOM pixel-wise clustering of the three-channel solar disk input (continuum intensity, unsigned magnetogram, and μ map) into a cluster-index map. Each pixel is assigned to its best matching unit (BMU) based on the Euclidean distance between its [I_pq,  B_pq,  μ_pq] vector and the learned SOM weight vectors, yielding an unsupervised segmentation of the disk into 400 photometric–magnetic surface regimes without predefined contrast thresholds.