A population of eagles, horses, and moles: Perceptual sensitivity to watermark disparity coherence

Disparity coherent watermarking has been introduced as a means to address the unique characteristics of stereoscopic visual content. This strategy has been reported to notably improve robustness performances in prior works, especially with respect to virtual view synthesis. While disparity coherence has always been conjectured to also provide better improved fidelity, it had never been properly evaluated. This perceptual study investigates the perception of three alternate watermarking strategies for stereo visual content on a population of thirty three observers. The analysis of the results reveals that there are three categories of observers and one of these categories, which amounts to nearly one third of our observers, is extremely sensitive to watermark coherence even for low-power watermarks. Moreover, the sensitivity to watermark coherence is found to be content dependent.