A unified framework for gamma nonlinearity and asynchronous crosstalk mitigation for optical camera communications

As a cutting-edge of multimedia-based data concealing technique, optical camera communication (OCC) has garnered considerable attention in fundamental platforms for many emerging applications. Typically, OCC employs smart screens or display arrays as transmitters and cameras as receivers. However, one key challenge for super-pixel level OCC is the phenomenon of asynchronous frame recovery and gamma correction, which is pivotal to facilitate seamless optical end-to-end interconnects. Off-the-shelf cameras are susceptible to the combined impact of nonlinear gamma effects and asynchronous inter-frame crosstalk, significantly degrading the video-based steganography. In this paper, we present a novel scheme termed nonlinear gamma correction with inter-frame crosstalk mitigation (NGC-ICM). It consists of the skewness-based gamma correction (SGC) and frame-level constrained independent component analysis (FCICA) module, to jointly post-equalize the nonlinear gamma effect and reception phase misalignment, thereby facilitating flexible multimedia data embedding. Theoretical analysis validates that the proposed NGC-ICM scheme, offers notable advantages such as rapid iterative convergence, low computational complexity, and a broad range of linear and nonlinear parameter compensation capabilities. From a quantitative analysis perspective, the NGC-ICM algorithm achieves a Q factor improvement of approximately 20 dB for the air link at 4.5 meters and 18 dB for the underwater link at 1.5 meters.