Another concept of bubble image analysis is to
perform full segmentation on froth image. A popular
methodology is watershed method[13]. The idea of
watershed is based on simulating water flows in a
topographic representation of image intensity[14]. As
shown in Fig.3, a three dimensional landscape can
describe the topography, which consists of valleys and
hills, representing the lower and the higher intensities of
an image, respectively. Suppose that a hole is punched in
each regional minimum. Put the model into a lake. Then
water is immersed from the bottom through the hole at a
uniform rate. When two lakes meet, the watershed can be
identified. The flooding will eventually be accomplished
until the entire landscape has been fully immersed.