转自https://www.cnblogs.com/iluzhiyong/p/4857877.html
当我们想要提取Region时，图像处理后，往往存在几个类似的Region，此时，需要根据Region的一些特殊特征，来选择指定的Region。

求Region指定特征值：region_features(Regions : : Features : Value)

根据特征值选择区域：select_shape(Regions : SelectedRegions : Features, Operation, Min, Max : )

Region特征一览：

特征 英 译 备注
area Area of the object 对象的面积
row Row index of the center 中心点的行坐标
column Column index of the center 中心点的列坐标
width Width of the region 区域的宽度
height Height of the region 区域的高度
row1 Row index of upper left corner 左上角行坐标
column1 Column index of upper left corner 左上角列坐标
row2 Row index of lower right corner 右下角行坐标
column2 Column index of lower right corner 右下角列坐标
circularity Circularity 圆度 0~1
compactness Compactness 紧密度 0~1
contlength Total length of contour 轮廓线总长
convexity Convexity 凸性
rectangularity Rectangularity 矩形度 0~1
ra Main radius of the equivalent ellipse 等效椭圆长轴半径长度
rb Secondary radius of the equivalent ellipse 等效椭圆短轴半径长度
phi Orientation of the equivalent ellipse 等效椭圆方向
anisometry Anisometry 椭圆参数，Ra/Rb长轴与短轴的比值
bulkiness Bulkiness 椭圆参数，蓬松度πRaRb/A
struct_factor Structur Factor 椭圆参数，Anisometry*Bulkiness-1
outer_radius Radius of smallest surrounding circle 最小外接圆半径
inner_radius Radius of largest inner circle 最大内接圆半径
inner_width Width of the largest axis-parallel rectangle that fits into the region 最大内接矩形宽度
inner_height Height of the largest axis-parallel rectangle that fits into the region 最大内接矩形高度
dist_mean Mean distance from the region border to the center 区域边界到中心的平均距离
dist_deviation Deviation of the distance from the region border from the center 区域边界到中心距离的偏差
roundness Roundness 圆度，与circularity计算方法不同
num_sides Number of polygon sides 多边形边数
connect_num Number of connection components 连通数
holes_num Number of holes 区域内洞数
area_holes Area of the holes of the object 所有洞的面积
max_diameter Maximum diameter of the region 最大直径
orientation Orientation of the region 区域方向
euler_number Euler number 欧拉数，即连通数和洞数的差
rect2_phi Orientation of the smallest surrounding rectangle 最小外接矩形的方向
rect2_len1 Half the length of the smallest surrounding rectangle 最小外接矩形长度的一半？？ smallest_rectangle2
rect2_len2 Half the width of the smallest surrounding rectangle 最小外接矩形宽度的一半
moments_m11 Geometric moments of the region 几何矩
moments_m20 Geometric moments of the region 几何矩
moments_m02 Geometric moments of the region 几何矩
moments_ia Geometric moments of the region 几何矩
moments_ib Geometric moments of the region 几何矩
moments_m11_invar Geometric moments of the region 几何矩
moments_m20_invar Geometric moments of the region 几何矩
moments_m02_invar Geometric moments of the region 几何矩
moments_phi1 Geometric moments of the region 几何矩
moments_phi2 Geometric moments of the region 几何矩
moments_m21 Geometric moments of the region 几何矩
moments_m12 Geometric moments of the region 几何矩
moments_m03 Geometric moments of the region 几何矩
moments_m30 Geometric moments of the region 几何矩
moments_m21_invar Geometric moments of the region 几何矩
moments_m12_invar Geometric moments of the region 几何矩
moments_m03_invar Geometric moments of the region 几何矩
moments_m30_invar Geometric moments of the region 几何矩
moments_i1 Geometric moments of the region 几何矩
moments_i2 Geometric moments of the region 几何矩
moments_i3 Geometric moments of the region 几何矩
moments_i4 Geometric moments of the region 几何矩
moments_psi1 Geometric moments of the region 几何矩
moments_psi2 Geometric moments of the region 几何矩
moments_psi3 Geometric moments of the region 几何矩
moments_psi4 Geometric moments of the region 几何矩