Fig. 8

Hierarchical Cluster Analysis of Raman image from a HeLa cell, the most commonly used human (cervical cancer) cell line. a White-light image; b corresponding Raman image of four clusters obtained by using AHCA multivariate technique; black regions indicate low SNR spectra (mostly buffer and substrate), which were removed prior to AHCA during the preprocessing stage; c average Raman spectra of four clusters; and d the difference spectrum (black) obtained by subtracting the average spectrum of the purple region from the average spectrum of the green region