PCA was effective and helpful in developing a classification system. However, it was inappropriate to perform two independent PCA models on ground truth images and query image, which was described in Figure 1 in Reference ``BRAIN MR IMAGE CLASSIFICATION USING MULTISCALE GEOMETRIC ANALYSIS OF RIPPLET, Progress in Electromagnetics Research, 137, 1-17, 2013''. In this note, we analyze the reason and revise Figure 1.
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