  Solar images taken simultaneously at different wavelengths in the EUV are
widely used for understanding structures such as flares, coronal holes, loops,
etc. The line-of-sight integration and the finite spectral resolution of EUV
telescopes, however, hinders interpretation of these individual images in terms
of temperature bands. Traditional approaches involve simple visualisation or
explicit modelling. We take a more empirical approach, using statistical
methods. The morphology of solar structures changes with the wavelength of
observation and, therefore, with temperature. We explore the possibility of
separating the different solar structures from a linear combination of images.
Using a blind source separation approach, we build a new set of statistically
independent "source" images from the original EUV images. Two techniques are
compared: the singular value decomposition and independent component analysis.
The source images show more contrast than the original ones, thereby easing the
characterisation of morphological structures. A comparison with the
differential emission measure shows that each source image also isolates
structures with specific emission temperatures.
