| area_center | Area and center of regions. |
| circularity | Shape factor for the circularity (similarity to a circle) of a region. |
| compactness | Shape factor for the compactness of a region. |
| connect_and_holes | Number of connection components and holes |
| contlength | Contour length of a region. |
| convexity | Shape factor for the convexity of a region. |
| diameter_region | Maximal distance between two boundary points of a region. |
| eccentricity | Shape features derived from the ellipse parameters. |
| elliptic_axis | Parameters of the equivalent ellipse. |
| euler_number | Calculate the Euler number. |
| find_neighbors | Search direct neighbors. |
| get_region_index | Index of all regions containing a given pixel. |
| get_region_thickness | Access the thickness of a region along the main axis. |
| hamming_distance | Hamming distance between two regions. |
| hamming_distance_norm | Hamming distance between two regions using normalization. |
| inner_circle | Largest inner circle of a region. |
| inner_rectangle1 | Largest inner rectangle of a region. |
| moments_region_2nd | Geometric moments of regions. |
| moments_region_2nd_invar | Geometric moments of regions. |
| moments_region_2nd_rel_invar | Geometric moments of regions. |
| moments_region_3rd | Geometric moments of regions. |
| moments_region_3rd_invar | Geometric moments of regions. |
| moments_region_central | Geometric moments of regions. |
| moments_region_central_invar | Geometric moments of regions. |
| orientation_region | Orientation of a region. |
| rectangularity | Shape factor for the rectangularity of a region. |
| roundness | Shape factors from contour. |
| runlength_distribution | Distribution of runs needed for runlength encoding of a region. |
| runlength_features | Characteristic values for runlength coding of regions. |
| select_region_point | Choose all regions containing a given pixel. |
| select_region_spatial | Pose relation of regions. |
| select_shape | Choose regions with the aid of shape features. |
| select_shape_proto | Choose regions having a certain relation to each other. |
| select_shape_std | Select regions of a given shape. |
| smallest_circle | Smallest surrounding circle of a region. |
| smallest_rectangle1 | Surrounding rectangle parallel to the coordinate axes. |
| smallest_rectangle2 | Smallest surrounding rectangle with any orientation. |
| spatial_relation | Pose relation of regions with regard to the coordinate axes. |