Fig. 2. Process of measuring the color value of the lesion and the surrounding mucosa. (A) A border line between the lesion and the surrounding mucosa (black) was drawn. (B) An outer line (blue) was drawn parallel to the border line, enclosing an area twice as large as the area enclosed by the border line. An inner line (green) was drawn inside and parallel to the border line, and the width between the border line and the inner line was equal to the width between the border line and the outer line. A rectangle (white line) was drawn in the center of the lesion with a width of one-third of the width of the lesion. (C) The sections separated by this rectangle and the 3 lines were the ROI of the lesion (red shaded area) and the surrounding mucosa (blue shaded area). The color value of the lesion and the surrounding mucosa was defined as the average of the color value in each ROI.

ROI = region of interest.