Abstract. Computed virtual chromoendoscopy with flexible spectral imaging color enhancement ͑FICE͒ is a new dyeless imaging technique that enhances mucosal and vascular patterns. However, a method for selecting a suitable wavelength for a particular condition has not been established. The aim of this study is to evaluate the color difference method for quality assessment of FICE images of the intrapapillary capillary loop in magnifying endoscopy for esophageal squamous cell carcinoma. The color difference between 60 microvessels and background mucosa observed using the magnifying endoscope was 8.31± 2.84 SD under white light and 12.26± 3.14 ͑p = 0.0031͒, 11.70± 4.49 ͑p = 0.0106͒, and 17.49± 5.40 ͑p Ͻ 0.0001͒ in FICE modes A, B, and C, respectively. The visibility scores for microvessels observed by medical students were 6.00± 1.12 points under white light and 11.1± 2.25 ͑p Ͻ 0.0001͒, 8.65± 2.06 ͑p = 0.0001͒, and 12.55± 2.56 ͑p Ͻ 0.0001͒ in FICE modes A, B, and C, respectively. Furthermore, the measurement of color difference was correlated with the visibility score assigned by medical students ͑Pear-son's correlation coefficient= 0.583, p Ͻ 0.0001͒ In conclusion, the color difference method corresponds to human vision and is an appropriate method for evaluation of endoscopic images.