Transferring barrier-free colors from images to maps to improve accessibility for users with color vision deficiencies

Color transfer is an important technique in map design, allowing mapmakers to apply colors from images—such as paintings and photographs—to maps without the need to design color schemes from scratch. However, existing color transfer methods often overlook the requirements of individuals with color vision deficiency, resulting in transferred colors that may be difficult for them to distinguish. To address this issue, this paper proposes an automatic method for transferring barrier-free colors from images to maps for individuals with color vision deficiencies. The method involves extracting colors from input images and building three optimization models to identify barrier-free colors for area, line, and point features. By representing map features with these optimized colors, barrier-free color schemes can be effectively transferred from images to maps. To evaluate our method, a case study was conducted using four images and a map of Suzhou as experimental data. Seventy-seven college students—including thirty-three with color vision deficiencies and forty-four with normal color vision—participated in tasks involving identification and comparison on the transferred maps. The results indicate that maps generated using the proposed method are easily readable for both groups, while also preserving the original color style of the reference images.