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4. Results
As a first example shown in Fig.1, the percentage of the area of the small enclosed region in the middle with respect to the larger enclosed area is 48.1%. The single-limit method of the line-scanning algorithm outperformed all other methods. It took only 0.72s on a Pentium III machine to compute the required result.


Fig.1 Relative percentage of area calculation
As a second example, consider the aerial image in Fig. 2(a). In order to compute the relative designated area with respect to the darken area, two colors are used to shade the required regions first, as shown in Fig. 2(b). Then we apply one of our algorithms to compute the relative percentage. The value is 11.7%. That is, the darken area (green colour) occupies 13.1% of the designated area (blue plus green colours). The time to compute this value takes only 1.98 sec.


Fig. 2(a). An aerial image

Fig. 2(b). Percentage of green area relative to blue+green area
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