Fig. 2From: Evaluation of dual-wavelength excitation autofluorescence imaging of colorectal tumours with a high-sensitivity CMOS imager: a cross-sectional studyClassification of lesion brightness in autofluorescence ratio images. a. Fresh resected specimen. b. No-signal group: In comparison to normal mucosa, the lesion does not appear bright (ratio image of a). c. Fresh resected specimen. d. High-signal group: In comparison to normal mucosa, the lesion appears bright (ratio image of c)Back to article page