Density plot of correctly predicted coronal holes (TPR) versus erroneously predicted coronal holes (FPR) obtained with SPoCA algorithm. The red crosses denote the individual results for the TPR and FPR for each of the 100 iterations, according to the training and evaluation protocol described in Section 4.2. (a) SVM (all attributes), (b) linear SVM (all attributes), (c) SVM (AIA attributes only), (d) linear SVM (AIA attributes only).