Does opencv have a function similar to size and bwperim in matlab?

Question

I am new to opencv and good at matlab

i want to write equalent of below to opencv

[mm,nn]=size(binaryimage);

bwperim(binaryimage);

Please can any one help

Answer 1

There is a library for these things: http://opencv.willowgarage.com/wiki/cvBlobsLib

Answer 2

For emulating bwperim you can do

Mat m;
Mat dilated = m.clone(); dilate(dilated,one_pixel_wide_element);
Mat output = dilated - m;

where the one_pixel_wide_element can be constructed using instructions from opencv:

  dilation_type = MORPH_RECT;
  dilation_size = 1;
  Mat element = getStructuringElement( dilation_type,
                  Size( 2*dilation_size + 1, 2*dilation_size+1 ),
                  Point( dilation_size, dilation_size ) );

This gives an outer boundary. For inner boundaries do erode (and m-eroded).