Region Growing - Simulation Examples

Simulation Examples

Here we show a simple example for region growing.

Figure 1 is the original image which is a gray-scale lightning image. The gray-scale value of this image is from 0 to 255. The purpose we apply region growing on this image is that we want to mark the strongest lightning part of the image and we also want the result to be connected without being split apart. Therefore, we choose the points having the highest gray-scale value which is 255 as the seed points showed in the Figure 2.

After determining the seed points, we have to determine the range of threshold. Always keep in mind that the purpose we want to do is to mark the strongest light in the image. The third figure is the region growing result from choosing the threshold between 225 and the value of seed points (which is 255). It means we only want to mark out the points whose gray-scale values are above 225.

If we make the range of threshold wider, we will get a result having a bigger area of the lightning region show as the Figure 4 and the Figure 5.

We can observe the difference between the last two figures which have different threshold value showed above. Region growing provides the ability for us to separate the part we want connected.

As we can see in Figure 3 to Figure 5, the segmented result in this example are seed-oriented connected. That means the result grew from the same seed points are the same regions. And the points will not be grown without connected with the seed points in the beginning. Therefore, we can mention that there are still lots of points in the original image having the gray-scale value above 155 which are not marked in Figure 5. This characteristic ensures the reliability of the segmentation and provides the ability to resist noise. For this example, this characteristic prevents us marking out the non-lightning part in the image because the lightning is always connected as one part.