Segmentations and Dimensionality Reduction

So far I have been learning a lot about these two terms. But I haven't quite really clear on the exact differences, theoretically.

Both of these are very important in defining regions in medical images, particularly in fMRI for my research. I am definitely in need to really master the theories before doing any major math research on these.

So, the topics that are interest me now:

• PCA, ICA, SIFT
• Sliding window approach
• Covariance/correlation matrices
• Functional Connectivity in fMRI

So much to learn, yet so little time. May Allah ease. :)