reduce the total dimensionality of the transformed image from 31 to 3. Figure
13.12b shows the transformed image, where the three PCA variables are
mapped to the RGB color space.
Independent Component Analysis Another unsupervised
unmixing approach to extract linearly independent signals from images is
independent component analysis (ICA). Like PCA, ICA develops a linear
transformation to project the data onto a different set of axes. But while PCA
attempts to decorrelate the data, ICA searches all possible projections of the data
to realize independence across all statistical orders. ICA can extract each signal
from the mixture as long as the recorded image is a linear combination of
independent signals. Two key assumptions required for ICA are tha ...