Schematic illustration of the tri-channel metasurface for watermarked structural-color nanoprinting and holographic imaging. Nanobricks with different sizes and orientations are arranged on the transparent substrate. By changing the illuminating condition and outgoing polarization of light, three types of images can be produced with the simple metasurface. Under the irradiation of unpolarized natural light, a structural-color nanoprinting image of landscape appears on the surface of the metasurface (channel 1). When an analyzer is inserted to control the polarization direction of the emergent light, the identical structural-color nanoprinting image but covered with a watermark pattern can be observed (channel 2). Additionally, a centrosymmetric holographic image can be projected in the far-field under the laser illumination at 620 nm (channel 3). Credit: Optics Express (2022). DOI: 10.1364/OE.472789