目录
- 效果
- 实现代码
效果
实现代码
using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using OpenCvSharp; using OpenCvSharp.Extensions; namespace OpenCvSharp_图像校正 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } string img = "test.png"; private void Form1_Load(object sender, EventArgs e) { pictureBox1.Image = new Bitmap(img); } private void button1_Click(object sender, EventArgs e) { Mat src = new Mat(img); //转化为灰度图 //Cv2.CvtColor(src, src, ColorConversionCodes.RGB2GRAY); InputArray kernel = Cv2.GetStructuringElement(MorphShapes.Rect, new OpenCvSharp.Size(3, 3)); Cv2.MorphologyEx(src, src, MorphTypes.Close, kernel, new OpenCvSharp.Point(-1, -1), 3); //Cv2.ImShow("MorphologyEx", src); /* ksize,高斯内核大小,ksize.width和ksize.height必须是正奇数,两者可以不相同,值越大越模糊 sigmaX,Y轴方向的标准差,值越大越模糊 sigmaY,X轴方向的标准差,值越大越模糊 */ Cv2.GaussianBlur(src, src, new OpenCvSharp.Size(11, 11), 2, 2); //Cv2.ImShow("GaussianBlur", src); //Canny边缘检测 Mat canny_Image = new Mat(); Cv2.Canny(src, canny_Image, 10, 30, 3, false); OpenCvSharp.Point[][] contours; HierarchyIndex[] hierarchly; /* findContours找到轮廓 第一个参数:单通道图像矩阵,可以是灰度图,但更常用的是二值图像,一般是经过Canny、拉普拉斯等边缘检测算子处理过的二值图像; 第二个参数:contours 第三个参数:hierarchy 第四个参数:轮廓的检索模式 取值一:CV_RETR_EXTERNAL 只检测最外围轮廓,包含在外围轮廓内的内围轮廓被忽略 取值二:CV_RETR_LIST 检测所有的轮廓,包括内围、外围轮廓,但是检测到的轮廓不建立等级关系,彼此之间独立,没有等级关系,这就意味着这个检索模式下不存在父轮廓或内嵌轮廓,所以hierarchy向量内所有元素的第3、第4个分量都会被置为-1,具体下文会讲到 取值三:CV_RETR_CCOMP 检测所有的轮廓,但所有轮廓只建立两个等级关系,外围为顶层,若外围内的内围轮廓还包含了其他的轮廓信息,则内围内的所有轮廓均归属于顶层 取值四:CV_RETR_TREE 检测所有轮廓,所有轮廓建立一个等级树结构。外层轮廓包含内层轮廓,内层轮廓还可以继续包含内嵌轮廓。 第五个参数:轮廓的近似方法 取值一:CV_CHAIN_APPROX_NONE 保存物体边界上所有连续的轮廓点到contours向量内 取值二:CV_CHAIN_APPROX_SIMPLE 仅保存轮廓的拐点信息,把所有轮廓拐点处的点保存入contours向量内,拐点与拐点之间直线段上的信息点不予保留 取值三和四:CV_CHAIN_APPROX_TC89_L1,CV_CHAIN_APPROX_TC89_KCOS使用teh-Chinl chain 近似算法 第六个参数:Point偏移量,所有的轮廓信息相对于原始图像对应点的偏移量,相当于在每一个检测出的轮廓点上加上该偏移量,且Point可以是负值。不填为默认不偏移Point() */ Cv2.FindContours(canny_Image, out contours, out hierarchly, RetrievalModes.External, ContourApproximationModes.ApproxSimple, new OpenCvSharp.Point(0, 0)); if (contours.Length == 0) { MessageBox.Show("边缘检测失败"); return; } Random rnd = new Random(); Scalar color; color = http://www.devze.comnew Scalar(0, 255, 0); for (int i = 0; i < contours.Length; i++) { color = new Scalar(rnd.Next(0, 255), rnd.Next(0, 255), rnd.Next(0, 255)); Cv2.DrawContours(src, contours, i, color, 2, LineTypes.Link4); } //Cv2.ImShow("contours"javascript, src); //求出面积最大的轮廓 double max_area = 0.0; double currentArea = 0.0; OpenCvSharp.Point[] max_contour = null; for (int i = 0; i < contours.Length; i++) { currentArea = Cv2.ContourArea(contours[i]); if (currentArea > max_area) { max_area = currentArea; max_contour = contours[i]; } } //多边形拟合凸包的四个顶点 OpenCvSharp.Point[] hull = Cv2.ConvexHull(max_contour); double epsilon = 0.02 * Cv2.ArcLength(max_contour, true); OpenCvSharp.Point[] approx = Cv2.ApproxPolyDP(hull, epsilon, true); if (approx.Length != 4) { MessageBox.Show("拟合凸包的四个顶点失败"); return; } Scalar scalar2 = new Scalar(0, 255, 255); Cv2.Line(src, approx[0], approx[1], scalar2, 1, LineTypes.Link4); Cv2.Line(src, approx[1], approx[2], scalar2, 1, LineTypes.Link4); Cv2.Line(src, approx[2], approx[3], scalar2, 1, LineTypes.Link4); Cv2.Line(src, approx[3], approx[0], scalar2, 1, LineTypes.Link4); //排序 Array.Sort(approx, (cs1, cs2) => { if (cs1 != null && cs1 != null) { if (cs1.Y > cs2.Y) Ufjptjd return 1; else if (cs1.Y == cs2.Y) { if (cs1.X < cs2.X) return 1; else return -1; } else return -1; } return 0; }); //算法找出的角点 OpenCvSharp.Point2f[] srcPt = new OpenCvSharp.Point2f[4]; srcPt[0] = approx[0]; srcPt[1] = approx[1]; srcPt[2] = approx[3]; srcPt[3] = approx[2]; //最小外接矩形 RotatedRect rect = Cv2.MinAreaRect(srcPt); Rect box = rect.BoundingRect(); OpenCvSharp.Point2f[] dstPt = new OpenCvSharp.Point2f[4]; dstPt[0].X = box.X; dstPt[0].Y = box.Y; dstPt[1].X = box.X + box.Width; dstPt[1].Y = box.Y; dstPt[2].X = box.X + box.Width; dstPt[2].Y = box.Y + box.Height; dstPt[3].X = box.X; dstPt[3].Y = box.Y + box.Height; Mat src2 = new Mat(img); Mat final = new Mat(); Mat warpmatrix = Cv2.GetPerspectiveTransform(srcPt, dstPt);//获得变换矩阵 Cv2.WarpPerspective(src2, final, warpmatrix, src.Size());//投射变换,将结果赋给final 编程 Bitmap temp = BitmapConverter.ToBitmap(final); pictureBox2.Image = temp; DrawLine(srcPt, dstPt); //Application.DoEvents(); //System.Threading.Thread.Sleep(1000); //pictureBox2.Image = CutImage(temp, (int)p2f[0].X, (int)p2f[0].Y, (int)p2f[2].X, (int)p2f[2].Y); } void DrawLine(OpenCvSharp.Point2f[] srcPt, OpenCvSharp.Point2f[] dstPt) { Bitmap bmp = new Bitmap(img); Graphics g = Graphics.FromImage(bmp); Pen pen = new Pen(Color.Red, 3); Pen pen2 = new Pen(Color.Blue, 3); g.DrawLine(pen, srcPt[0].X, srcPt[0].Y, srcPt[1].X, srcPt[1].Y); g.DrawLine(pen, srcPt[1].X, srcPt[1].Y, srcPt[2].X, srcPt[2].Y); g.DrawLine(pen, srcPt[2].X, srcPt[2].Y, srcPt[3].X, srcPt[3].Y); g.DrawLine(pen, srcPt[3].X, srcPt[3].Y, srcPt[0].X, srcPt[0].Y); g.DrawLine(pen2, dstPt[0].X, dstPt[0].Y, dstPt[1].X, dstPt[1].Y); g.DrawLine(pen2, dstPt[1].X, dstPt[1].Y, dstPt[2].X, dstPt[2].Y); g.DrawLine(pen2, dstPt[2].X, dstPt[2].Y, dstPt[3].X, dstPt[3].Y); g.DrawLine(pen2, dstPt[3].X, dstPt[3].Y, dstPt[0].X, dstPt[0].Y); pictureBox1.Image = bmp; } /// <summary> /// 剪裁图片 /// </summary> /// <param name="src">原图片</param> /// <param name="left">左坐标</param> /// <param name="top">顶部坐标</param> /// <param name="right">右坐标</param> /// <param name="bottom">底部坐标</param> /// <returns>剪裁后的图片</returns> public Image CutImage(Image src, int left, int top, int right, int bottom) { Bitmap srcBitmap = new Bitmap(src); int width = right - left; int height = bottom - top; Bitmap destBitmap = new Bitmap(width, height); using (Graphics g = Graphics.FromImage(destBitmap)) { g.Clear(Color.Transparent); //设置画布的描绘质量 g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; g.SmoothingMode = System.Drawing.Drpythonawing2D.SmoothingMode.HighQuality; g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; g.DrawImage(srcBitmap, new Rectangle(0, 0, width, height), left, top, width, height, GraphicsUnit.Pixel); } return destBitmap; } } }
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