.. _book_fig_chapter7_fig_spec_decompositions:


SDSS spectra Decompositions
---------------------------
Figure 7.4

A comparison of the decomposition of SDSS spectra using PCA (left panel -
see Section 7.3.1), ICA (middle panel - see Section 7.6) and NMF (right panel
- see Section 7.4). The rank of the component increases from top to bottom. For
the ICA and PCA the first component is the mean spectrum (NMF does not require
mean subtraction). All of these techniques isolate a common set of spectral
features (identifying features associated with the continuum and line
emission). The ordering of the spectral components is technique dependent.



.. image:: ../images/chapter7/fig_spec_decompositions_1.png
    :scale: 100
    :align: center


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