| ::area_center_xld | Area and center of gravity (centroid) of contours and polygons. |
| ::contour_point_num_xld | Return the number of points in an XLD contour. |
| ::dist_ellipse_contour_xld | Distance of contours to an ellipse. |
| ::fit_circle_contour_xld | Approximation of XLD contours by circles. |
| ::fit_ellipse_contour_xld | Approximation of XLD contours by ellipses or elliptic arcs. |
| ::fit_line_contour_xld | Approximation of XLD contours by line segments. |
| ::get_contour_angle_xld | Calculate the direction of an XLD contour for each contour point. |
| ::get_contour_attrib_xld | Return point attribute values of an XLD contour. |
| ::get_contour_global_attrib_xld | Return global attributes values of an XLD contour. |
| ::get_regress_params_xld | Return XLD contour parameters. |
| ::info_parallels_xld | Return information about the gray values of the area enclosed by XLD parallels. |
| ::length_xld | Length of contours or polygons. |
| ::local_max_contours_xld | Select XLD contours with a local maximum of gray values. |
| ::max_parallels_xld | Join modified XLD parallels lying on the same polygon. |
| ::moments_any_xld | Arbitrary geometric moments of contours or polygons. |
| ::moments_xld | Geometric moments M20, M02, and M11 of contours or polygons. |
| ::query_contour_attribs_xld | Return the names of the defined attributes of an XLD contour. |
| ::query_contour_global_attribs_xld | Return the names of the defined global attributes of an XLD contour. |
| ::select_contours_xld | Select XLD contours according to several features. |