Figure 4
PR curves of the classifiers trained on aggregated features from the filtered crowd raters under each privacy condition. Precision is plotted against recall for different class cutoffs of the logistic regression classifier’s output probability. The color of the curve represents the privacy condition: blue represents unaltered videos, green represents face obfuscation, red represents pitch shift, and purple represents face obfuscation and pitch shift. Plots show aggregated results using the (A,D) mode, (B,E) median, and (C,F) round of the mean of the crowd worker responses. The ROC curves are shown for both the LR5 (A–C) and LR10 (D–F) classifiers. Area under the curves increasingly closer to 1.0 indicate increasingly better performance, and a value of 0.5 indicates random guessing by the classifier.
