Color change is a useful marker for the endoscopic identification of chronic atrophic gastritis (CAG) and gastric cancer (GC). Several histopathological studies have suggested a correlation between certain gastrointestinal lesions and intramucosal vascularity. The aim of this study is to investigate the association between the color and mucosal microvascular density of CAG and early GC using linked color imaging (LCI). In this study, Lesions diagnosed as CAG and early GC will be observed using LCI. In each image, the color values of atrophic and non-atrophic mucosa, as well as cancerous and non-cancerous mucosa, will be quantified using the International Commission on Illumination 1976 (L∗, a∗, b∗) color space. Histological microvascular density in biopsy or resected specimens will be evaluated using CD31 immunostaining. Color differences at the atrophic border and cancerous border, defined as Euclidean distances of color values between the atrophic and non-atrophic mucosa, as well as cancerous and non-cancerous mucosa, will be calculated according to mucosal microvascular density.