# enum cv::RetrievalModes

## Overview

mode of the contour retrieval algorithm More…

#include <imgproc.hpp>

enum RetrievalModes
{
RETR_EXTERNAL  = 0,
RETR_LIST      = 1,
RETR_CCOMP     = 2,
RETR_TREE      = 3,
RETR_FLOODFILL = 4,
};


## Detailed Documentation

mode of the contour retrieval algorithm

### Enum Values

RETR_EXTERNAL


retrieves only the extreme outer contours. It sets hierarchy[i][2]=hierarchy[i][3]=-1 for all the contours.

RETR_LIST


retrieves all of the contours without establishing any hierarchical relationships.

RETR_CCOMP


retrieves all of the contours and organizes them into a two-level hierarchy. At the top level, there are external boundaries of the components. At the second level, there are boundaries of the holes. If there is another contour inside a hole of a connected component, it is still put at the top level.

RETR_TREE


retrieves all of the contours and reconstructs a full hierarchy of nested contours.