Yes. They're very effective. Think about the effectiveness of images of the Holocaust, for example.
Here's one link I found.
One major danger I see with the graphic-pictures approach to abortion protesting is that those who would justify abortion rely upon the dehumanization of the unborn, and it is that dehumanization which most needs to be countered. Depicting fetuses as gory messes of mutilated body parts does not impart humanity to them.
Better might be photographs or video of people who were initially not wanted and whose mothers may have considered abortions but, for whatever reasons, decided against. Focus on the fact that unborn babies are people. Herod and Phaoroah were condemned by history for the wanton slaughter of babies who had done nothing wrong, and yet today's victims are no less innocent.
BTW, some efforts to cleanse the adoption agencies of liberals might be good too.