During the last few months I have been developing a new version of the Semi-Automatic Classification Plugin (SCP) for QGIS. This new SCP version 4.0 codename "Frascati" (dedicated to the ESA ESRIN located in Frascati (Italy), which is the European centre of Earth observation missions, and it is involved in the development of the Copernicus Sentinel satellites in particular for the acquisition, distribution and exploitation of data) will be officially released on February 16th 2015.
I have tried to add several new functions both to the user interface and the processing tools. In particular, a new SCP menu in located in the main menu bar of QGIS. One of the main achievements is the optimization of the Maximum Likelihood algorithm, which is considerably faster than before.
Another major change is that temporary ROIs are displayed as overlay, avoiding the loading of temporary shapefiles in QGIS. Also, new options allow for the automatic refresh of temporary ROIs changing ROI parameters.
A combo box allows for the rapid visualization of RGB color composites, which is useful for image interpretation.
New custom functions are available for splitting raster bands, converting classifications to shapefile, reclassifying classifications (also using Python expressions).
I have summarized the main changes in the following video.