Dwarf-galaxy sized dark matter halos may be detectable when a bright background source is gravitationally lensed on scales of milliarcseconds. Such effects can be caused by dark galaxies as well as luminous ones. Here we discuss conditions for detecting a luminous lensing object through direct imaging, via measurements of the point spread function (PSF) to subtract the quasar from the image, revealing the quasar host galaxy and any luminous lens. The technique applies to both types of millilensing effect, i.e. magnification and image splitting. We show that luminous dwarf-galaxy lenses should be detectable with this method up to redshifts z~0.2.