Learning OpenCV, 2nd Edition

int mode, // Contour retrieval mode (Figure 8-2)

int method, // Approximation method

cv::Point offset = cv::Point() // (optional) Offset every point

);

The be

inte ted as binary (i.e., as if all nonzero pixels were equivalent to one another). When it runs,

g one of the two forms of

fir

rpre

st argument is the input image; this image should be an 8-bit single-channel image and will

cv::findContours() will actually use this image as scratch space for computation, so if you need that

image for anything later, you should make a copy and pass that to cv::findContours(). The second

argument is an array of arrays, which in most practical cases will mean an STL vector of STL vectors. This

will be filled with the list of contours found (i.e., it will be a vector of contours, where contours[i] will

be a specific contour and thus contours[i][j] would refer to a specific vertex in contour[i]).

The next argument can be either supplied or not supplied (by usinhierarchy

the function shown above). If supplied, hierarchy is the output that describes the tree structure of the

contours. The output hierarchy will be an array (again typically an STL vector) with one entry for each

contour in contours. Each such entry will contain an array of four elements, each indicating the node to

which a particular link from the current node is connected (Error! Reference source not found.).

Figure 8-2: ...