i want an algorithm to convert an 8 connected labelling into a 4 connected labelling on this binary image ?

Answer 1

[Image Analyst]

Simply pass in 4 as the second argument indicating that you want to consider it as 4-connected.

labeledImage = bwlabel(binaryImage, 4);

[Amir]

SIR, its a built in function, i need an alternative code?

[Image Analyst]

Why? Is it homework? Is so, you should have added the tag homework and mentioned that first. Here is a link to the algorithm that you can program up yourself from scratch: http://en.wikipedia.org/wiki/Connected-component_labeling