Contrasting shadow for occluder light suppression from one-shot image

Two main problems for front projection systems when a user appears between a screen and a projector are 1) shadows being cast on a screen and 2) the user being illuminated due to undesirable strong projection light. To solve these problems, it is necessary to know which projectors are occluded by a user and cast a shadow. We propose a method that suppresses occluder light from a single image based on the fact that the darkness of shadows on a screen is differentiated when projectors have different luminance. Contrary to previous approaches, our method utilizes different alpha masks for each projector to contrast shadows on a screen. This enables us to clarify the relationship between the shadow on a screen and the occluded projector. Additionally, by differentiating all projector luminances, our method makes it possible to discriminate shadows even when some shadow regions overlap on a screen. We implemented the proposed method into a three-projector system to demonstrate its effectiveness.