Comparison of different Segmentation Techniques

S.No Segmentation

Technique

Information

used in

Segmentation

Extends

to N-D

Method of

Segmentation

Advantages Disadvantages

1 Thresholding Colour No Simple

Comparison

Between

Pixels And

The

Threshold

When the intensity of the

pixels is larger/smaller than a

predefined threshold, those

pixels are classified as

foreground. Otherwise, they

will be viewed as

background.

Threshold based approaches

are the simplest, easiest and

fast ones among all of the

existed segmentation

methods.

The difficulty is that it is

not easy to find an

appropriate threshold

which can separate the

image into two groups

directly.

This method also requires

the foreground and

background in the image

have obviously different

intensity values.

2 Live Wire Edge No 2D Graph

Search Using

Dynamic

Programming

More general, reduced

initialization.

Real-time: User immediately

sees whether desired contour

was obtained or not and can

adjust contour otherwise.

Direct control of contour.

Sub-pixel accuracy not

possible.

Contour depends on

weighting between internal

and external costs.

May ignore jagged edges

or snap to wrong edges.

3 Snakes/Activ

e contours

Edge No Energy

Minimization

of Internal

and External

Functions

They autonomously and

adaptively search for the

minimum state.

External image forces act

upon the snake in an intuitive

manner. Incorporating

Gaussian smoothing in the

image energy function

introduces scale sensitivity.

They can be used to track

dynamic objects.

They are sensitive to local

minima states, which can

be counteracted by

simulated annealing

techniques. Minute

features are often ignored

during energy

minimization over the

entire contour.

Their accuracy depends on

the convergence policy.

4 Graph cut Colour and

Edge

Yes Max-

Flow/Min-

Cut

Algorithm

For Energy

Minimization

The energy function is

constructed based on regional

and boundary information and

it can achieve globally

optimal result.

Taking the sorce and sink

points and grouping the

points into source region

and sink region

automatically with out

human interaction is

difficult.