0.7-OpenCvSharp4 形态学操作

0.7 OpenCvSharp4 形态学操作

1. 开操作 Open
   开操作：先腐蚀后膨胀，假设背景是黑色，对象是前景色，可以去除较小的对象。
2. 闭操作 Close
   闭运算：先膨胀后腐蚀。假设背景是黑色，对象是前景色，可以填充小洞。
3. 形态学梯度 Gradient
   形态学梯度：膨胀减腐蚀,又称为基本梯度。目的：突出高亮区域的外围，为轮廓查找提供新思路。
4. 顶帽 TopHat
   顶帽：原图与开操作的差值图。
5. 黑帽 BlackHat
   黑帽：闭操作与原图的差值图。

//
// 摘要:
//     Performs advanced morphological transformations 形态变换
//
// 参数:
//   src:
//     Source image
//
//   dst:
//     Destination image. It will have the same size and the same type as src
//
//   op:
//     Type of morphological operation 形态运算类型 open、close etc
//
//   element:
//     Structuring element 结构元素
//
//   anchor:
//     Position of the anchor within the element. The default value (-1, -1) means that
//     the anchor is at the element center
//
//   iterations: 迭代次数
//     Number of times erosion and dilation are applied. [By default this is 1]
//
//   borderType:
//     The pixel extrapolation method. [By default this is BorderType.Constant]
//
//   borderValue:
//     The border value in case of a constant border. The default value has a special
//     meaning. [By default this is CvCpp.MorphologyDefaultBorderValue()]
public static void MorphologyEx(InputArray src, OutputArray dst, MorphTypes op, [NullableAttribute(2)] InputArray? element, Point? anchor = null, int iterations = 1, BorderTypes borderType = BorderTypes.Constant, Scalar? borderValue = null);

//GetStructuringElement它是用来决定操作的性质
// 摘要:
//     Returns a structuring element of the specified size and shape for morphological 返回形态学的指定大小和形状的结构化元素
//     operations. The function constructs and returns the structuring element that
//     can be further passed to erode, dilate or morphologyEx.But you can also construct
//     an arbitrary binary mask yourself and use it as the structuring element.
//
// 参数:
//   shape:
//     Element shape that could be one of MorphShapes  元素MorphShapes类型
//矩形：MorphShapes.Rect;交叉形：MorphShapes.Cross; 椭形：MorphShapes.Ellipse;
//   ksize:
//     Size of the structuring element. 结构元素大小
public static Mat GetStructuringElement(MorphShapes shape, Size ksize);

实现代码

//开运算
OpenCvSharp.Size size = new OpenCvSharp.Size(3, 3);
Mat kerenl = Cv2.GetStructuringElement(MorphShapes.Rect,size);
Cv2.MorphologyEx(s2,dst,MorphTypes.Open,kerenl); //开运算
Cv2.MorphologyEx(s2,dst,MorphTypes.Close,kerenl); //闭运算
Cv2.MorphologyEx(s2,dst,MorphTypes.Gradient,kerenl);//形态学梯度
Cv2.MorphologyEx(s2,dst,MorphTypes.TopHat,kerenl);//顶帽
Cv2.MorphologyEx(s2,dst,MorphTypes.BlackHat,kerenl);//黑帽

形态学操作提取水平和垂直直线
步骤：

1. 将输入的彩色图像转换为灰度图像
2. 将灰度图像转换为二值图像
3. 定义结构元素，开操作：先腐蚀后膨胀，提取水平和垂直直线。

Mat s3 = Cv2.ImRead("D:\\OpenCV\\Topencv\\CsharpOpenCv\\CsharpOpenCv\\2.png");
Mat gray3 = new Mat(s3.Size(),s3.Type()) ; 
Mat binImage = new Mat(s3.Size(),s3.Type());
Cv2.CvtColor(s3,gray3,ColorConversionCodes.BGR2GRAY);//灰度图像
Cv2.AdaptiveThreshold(gray3,binImage,255,AdaptiveThresholdTypes.MeanC,ThresholdTypes.Binary,15,-2);//二值图像
OpenCvSharp.Size hsize = new OpenCvSharp.Size(s3.Cols / 16, 1);
OpenCvSharp.Size vsize = new OpenCvSharp.Size(1, s3.Rows/16);
Mat hline = Cv2.GetStructuringElement(MorphShapes.Rect,hsize);
Mat vline = Cv2.GetStructuringElement(MorphShapes.Rect,vsize);

Mat tmp = new Mat(s3.Size(),s3.Type()); 
Mat dst = new Mat(s3.Size(),s3.Type()); 
Cv2.Erode(binImage,tmp,hline);
Cv2.Dilate(tmp,dst,hline);