Q:

how to label a binarized image? 

please help me to segment a image in binary image...
more clearly,
i got a image from background subtraction, which is binary...means, the object area is of white color and non object object is black..now problem is how to label that white area?  
i m using c#.net. 

A:

If by "label the white area" you just mean create a bucket with a label (e.g., "TheObject") and add all the connected white pixels to it, then the most straightforward way is the so-called "sequential algorithm". 
The two-pass algorithm described here is also easy to implement.