In one aspect, embodiments disclosed herein relate to a lens-free imaging system. The lens-free imaging system includes: an image sampler, a radiation source, a mask disposed between the image sampler and a scene, and an image sampler processor. The image sampler processor obtains signals from the image sampler that is exposed, through the mask, to radiation scattered by the scene which is illuminated by the radiation source. The image sampler processor then estimates an image of the scene based on the signals from the image sampler, processed using a transfer function that relates the signals and the scene.