Sˇasˇic and Clark [
23] investigated the performance of
Raman line-mapping compared with global illumination
Raman systems for the analysis of tablets and formulation
blends. A pushbroom configuration was used in the linemapping
experiment, while a staring imager configuration
was used in the global experiment. Raman line-mapping
technology was demonstrated as preferable for identifying
minor components in samples, whereas the global illumination
system was recommended for imaging of spatially isolated
strong Raman scatterers. These researchers also
reported a novel chemometric technique for analysis of
Raman Images of pharmaceutical samples [56]. This
method, called sample-sample two-dimensional correlation,
involves analysis of the covariance matrix of the Raman
mapping spectral matrix. The most unique spectra in the
mapping matrix are identified by analysing the slices of
the covariance matrix at positions where the covariance
values are maximum; Chemical Images are then produced
by visual selection of the wavenumbers in the extracted
spectra that are least overlapped. The authors demonstrated
that this method was suitable for producing reliable
images of unknown samples of pharmaceutical tablets containing
up to 4 active components.