Dynamic‐Triangle‐Modulation Cutting: A Novel Route to High‐Fidelity Structural Color Image Reproduction With Wide Gamut

ABSTRACT Structural coloration offers a compelling alternative to conventional dyes and pigments, yet achieving high‐fidelity structural color image reproduction with high spatial resolution and wide color gamut remains challenging. Here, a dynamic‐triangle‐modulation cutting method is proposed for deterministic machining of blazed nano‐gratings on brass surfaces, enabling million‐pixel structural color images with 5 µm × 20 µm pixels. By pixel‐wise modulating the frequency and height of the triangle trajectory, the spacing, height, and blaze angle of the blazed nano‐gratings are controllably regulated, enabling coordinated tuning of structural color chromaticity and brightness. Guided by an optical diffraction model, a mapping among trajectory parameters, grating topography, and structural color properties is established. Variable‐ratio dual‐color mixing is further introduced within pixels to enrich color expression and smooth color transitions. The resulting structural colors cover relative gamut areas of 140.8% of sRGB, 104.4% of Adobe RGB, and 74.4% of Rec. 2020. The experimental images agree well with simulated images, showing accurate chromatic distribution, clear brightness gradation, and delicate details. Moreover, dual‐layer optically variable devices are demonstrated, enabling two distinct images to be selectively displayed under designed incident angles without noticeable crosstalk. This method provides a scalable route toward low‐cost, large‐area structural coloration of ductile metallic materials.