Region growing

Bottom-up procedure that starts with a set of seed pixels. The aim is to grow a uniform connected region from each seed. A pixel is added to a region if: 
· it has not been assigned to another region 
· it is a neighbour of the region 
· the new region (old region + new pixel) is still uniform 
The uniformity of the region R is decided upon the following rule:
P(R is uniform) = TRUE if |f(x, y) - mR| < Th, for all (x, y) in R
where mR represents the mean value (gray or RGB) of all pixels in the region except pixel (x, y), and Th is a threshold. 

You can create seeds in the original image by clicking in it. You can remove a seed with the right button of your mouse, or remove all seeds with the 'Remove seeds' button. 
Then select the connectivity (4 or 8 neighbourhood) and the threshold value defined above.