Research Article

Development of a System to Assist Automatic Translation of Hand-Drawn Maps into Tactile Graphics and Its Usability Evaluation

Figure 4

Using the top-hat transformation for shading correction, the top-hat transformation corrects the effects of nonuniform illumination, and, as a result, the fine binary image is created using Otsu’s method.
357380.fig.004a
(a) Original image
357380.fig.004b
(b) Thresholded image by Otsu’s method
357380.fig.004c
(c) Thresholded top-hat image