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. 2021 Dec 10;8:733241. doi: 10.3389/fmed.2021.733241

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Copyright © 2021 Li, Li, Zhang, Liang, Chen, Ye and Lin.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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Different methods to help patients with color blindness. The top figure indicates healthy vision in each pair of figures, while the bottom indicates patients with protanopia. (A) The natural scene. The patients with protanopia cannot distinguish the apples in red and the leaves in green. (B) The daltonization method (27). All colors are shifted to achieve less confusing color combinations. (C) The highlight method (26). Once the patients want to distinguish any color, the target color will be replaced by other colors that are easier to distinguish. In this case, red is replaced by pink. (D) The contrast method (26). In this case, red is replaced by yellow, and green is replaced by blue. (E) The outline method (26). In this case, the areas in red are outlined in order to be distinguished easily. (F) The method of using icons (30). In this case, the areas in red are indicated by the arrows.