The inclusion criteria were images

The inclusion criteria were images with standard white light, chromoendoscopy using indigo carmine spraying, and narrow band imaging (NBI).The exclusion criteria were any images that were magnified as well as poor quality images resulting from less insufflation of air, post-biopsy bleeding,halation, blur, defocus, or mucus. After selection, 13,584 images were collected for 2639 histologically proven gastric cancer lesions as a training image data set. At least one gastric cancer lesion was presented in all images, and multiple images were prepared for a same lesion to include differences in angle, distance, and extension of the gastric wall.All images of gastric cancer lesions were marked manually by an author (TH) who is an expert on gastric cancer and a board-certified trainer at the Japan Gastroenterological Endoscopy Society. The author (TH) carefully marked the range of cancer lesions using rectangular frames (Figs.1,2,3).