LiPro: displaying concurrent image viewing and imperceptible positioning using visible light

Abstract

Visible light can be used to achieve effective human interaction with projectors. However, current visible light-based projectors for the target positioning either lose the image viewing function or cause abnormal luminance changes perceived by human eyes, which is not practical for real-world applications. Therefore, we propose a smart lighting-based projector system, LiPro, which can display imperceptible target positioning and any image viewing, simultaneously. In a nutshell, we propose what we believe to be a novel color space conversion modulation scheme to transmit the landmark information, which adds δ and −3δ color intensity value on the red (R) channel and blue (B) channel according to the YCbCr color space analysis, so that human eyes are imperceptible to light intensity changes. Then, we propose the dual-channel decision demodulation scheme, which demodulates the received light signals on both the R channel and B channel at the same time to decide and increase the correctness of the landmark recognition. In the end, we use off-the-shelf devices to implement LiPro to evaluate its performance, and results from extensive experiments show that our LiPro can achieve centimeter-level target positioning under any image viewing conditions.