Fig. 1

Illustration of the image processing to obtain the iris maps of tumour location and extent. A Four representative iris melanomas from the present study are drawn by the drawing tools of PowerPoint (Microsoft Corp., Redmond, WA, USA) on standardised iris drawing charts of right eyes. B A custom-made Matlab program (The MathWorks, Natick, MA, USA) is used to merge the original drawings and display the number of overlapping tumours by different shades of grey. C After individual filtering of the tumour drawings, the resulting image appears smoother with less disturbing sharp edges. D The image is then colour-coded with a blue-to-red gradient indicating increasing brightness. The top of the colour scale (dark red) represents the maximum number of overlapping tumours, which in this example is 4