Visualization for our whitening example. In the left panel, the mixture signals are plotted in red stars. This panel also shows the principal components (⁠$PC1$ and $PC2$⁠). In the top right panel, the data in a blue color represent the projected data onto the PCA space. The data are then normalized to be with a unit variance (the bottom right panel). In this panel, the data in a green color represent the whitened data. A color version of this figure is available online.