Generic strategy for object detection
The framework you cope with is semi supervised. You have mostly unlabelled data and you can have some labeled data by manual labelling.

Active learning is one method to cope with the situation, by focusing your labelling efforts in the most beneficial areas. You can read a survey on these techniques at Settles, Burr (2010), "Active Learning Literature Survey" (PDF), Computer Sciences Technical Report 1648. University of Wisconsin–Madison, retrieved 2014-11-18


Please note that even if you are focusing your labelling efforts using active learning, it is still a significant constraint.

There are other methods of copying with semi-supervised framework, like co training.The classical reference on co-training is "Blum, A., Mitchell, T. Combining labeled and unlabeled data with co-training. COLT: Proceedings of the Workshop on Computational Learning Theory, Morgan Kaufmann, 1998, p. 92-100"