Directory for storing images for visualizaiton should be provided

[sbobek]

Currently it is assumed that the visualization compoenets are stored in a directory called histograms. Once someone give a path for a filename, not a name, the relative paths are out of sync and visualization is not working.
This should be fixed by providing additional parameter specifying the root dir for visualization, or by extracting and updating path from the filename if someone gives it in that way.