Figure 1.

Methods of color image analysis. (a) Example of the feedback guidelines on the monitor, which are shown to a subject during the image acquisition process. (b) Examples of the dark and high-luminance regions in the acquired images. Green pixels indicate high-luminance regions with L* values over 85, and blue pixels indicate dark regions with L* values under 30. (c) A color checker in the tongue image for the color correction analysis. The left 6 samples and right 6 samples were used for achromatic and chromatic color correction, respectively. (d) Average of the two-dimensional color histogram of 454 subjects. Seven color ranges (V1–V7) were selected for statistical analysis.