2.2 Annotation of images
All selected images of vocal cord leukoplakia were independently annotated by 2 senior expert endoscopists with at least 10 years of laryngoscopy experience; they did not participate in manipulating the laryngoscope that took the targeted images, but were not blinded to laryngoscopic findings and pathology. The boundaries of lesions in the image were annotated with the LabelMe application (https://github.com/wkentaro/labelme ) and used to represent the actual lesion area within the image.