Notes on customization of Voreen:

Added line
    ilResetWrite();
in 430:
    ilTexImage(size.x, size.y, 1, 4, IL_RGBA, IL_UNSIGNED_SHORT, colorBuffer);
    ilEnable(IL_FILE_OVERWRITE);
    ilResetWrite();
    ILboolean success = ilSaveImage(const_cast<char*>(filename.c_str()));
    ilDeleteImages(1, &img);
of ../ext/voreen/src/core/ports/renderport.cpp
due to an strange bug caused by undefined iopenw function in DevIL library
IMPORTANT: it would be better if this is executed statically