Finding continuous parts in a mask (ie a binary matrix)

[Antoine Monmayrant]

Hi everyone,

I have question that is more about image filtering than scilab, but I 
haven't found any answer so far so I'm turning towards scilab users.
I am looking for a way to determine continuous parts in a matrix made of 
1 or 0.
Basically, this matrix is used as a mask to filter an image and I need 
to determine the number of isolated "grains" (ie continuous parts where 
the matrix is equal to 1) in this mask.
As an example, here is a mask:

-->mask
  mask  =

     0.    0.    0.    0.    0.    0.    0.    0.    0.    0.
     0.    0.    0.    0.    0.    0.    1.    1.    1.    0.
     0.    0.    0.    0.    0.    0.    1.    1.    1.    0.
     0.    0.    0.    0.    0.    0.    1.    1.    1.    0.
     0.    1.    1.    0.    0.    0.    0.    0.    0.    0.
     0.    1.    1.    1.    0.    0.    0.    0.    0.    0.
     0.    0.    1.    1.    0.    0.    0.    0.    0.    0.
     0.    0.    0.    0.    0.    0.    0.    0.    0.    0.
     0.    0.    0.    0.    0.    0.    0.    0.    0.    0.
     0.    0.    0.    0.    0.    0.    0.    0.    0.    0.


It contains 2 "grains", one in the upper-right corner, and one in the 
middle-left.
I would like to be able to isolate them in order to determine their 
position in the matrix, size,...
Do any of you know of a good algorithm to achieve this?
Do any of you know what are the relevant names or keywords associated to 
this kind of algorithm?

Thank you in advance,

Antoin