C#图像处理OpenCV开发指南（CVStar，04）——图片像素访问与多种局部放大效果的实现代码

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使用本文代码需要预先设置一点开发环境，请阅读另外一篇博文：

C#图像处理OpenCV开发指南（CVStar，03）——基于.NET 6的图像处理桌面程序开发实践第一步 blog.csdn.net/beijinghorn/article/details/134684471?spm=1001.2014.3001.5502

1 功能需求

（1）读取图片；并显示于窗口；可缩放；

（2）可访问图片指定位置像素信息；

（3）提取局部图片（ROI）

（4）有 拾取框；

（5）局部放大（连续型放大）；

（6）支持 大像素 型得局部放大；

（7）支持 圆形 像素的局部放大；

2 代码分段讲解

前面一个博文中出现过的代码不再赘述。

2.1 访问图片指定位置像素信息 Vec3b cx = zmt.At<Vec3b>(y, x);

y,x 指定的位置；顺序不要搞错啦！ 

返回的数据类型 Vec3b 是 byte[] 类型的；BGR顺序；cx[0] 为 Blue，cx[1] 为 Green；cx[2] 为 Red；这个与一般的图片信息 RGB 顺序不同；

2.2 提取局部图片（ROI） Mat zmt = new Mat(src, new Rect(gx, gy, gw, gh));

gx,gy 为左上角坐标；

gw,gh 为局部图片的宽度与高度（像素）。

2.3 拾取框绘制 int gw = picResult.Width / PixelSize; int gh = picResult.Height / PixelSize; Bitmap bmp = new Bitmap(picSource.Width, picSource.Height); Graphics g = Graphics.FromImage(bmp); g.DrawImage( image: img, destRect: new Rectangle(0, 0, bmp.Width, bmp.Height), srcX: 0, srcY: 0, srcWidth: img.Width, srcHeight: img.Height, srcUnit: GraphicsUnit.Pixel); g.DrawRectangle(new Pen(Color.Yellow), mouseAtX - gw / 2, mouseAtY - gh / 2, gw, gh); picSource.Image = bmp; 2.4 光滑的（插值的）局部放大

图片的局部放大是取局部图片，放大显示。或者直接将图片放大显示并进行移位。

非 OpenCV 方式：

Bitmap bmp = new Bitmap(picResult.Width, picResult.Height); Graphics g = Graphics.FromImage(bmp); g.DrawImage( image: picSource.Image, destRect: new Rectangle(0, 0, bmp.Width, bmp.Height), srcX: gx, srcY: gy, srcWidth: gw, srcHeight: gh, srcUnit: GraphicsUnit.Pixel); picResult.Image = bmp;

OpenCV方式

Mat zmt = new Mat(src, new Rect(gx, gy, gw, gh)); picResult.Image = CVUtility.Mat2Bitmap(zmt); PicAutosize(picResult); 2.5 非插值的大像素型放大

非插值的大像素型放大是指将原图的每个像素放大为一个矩形（块）显示。

Mat zmt = new Mat(src, new Rect(gx, gy, gw, gh)); Bitmap bmp = new Bitmap(picResult.Width, picResult.Height); Graphics g = Graphics.FromImage(bmp); g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; for (int y = 0; y < gh; y++) { for (int x = 0; x < gw; x++) { Vec3b cx = zmt.At<Vec3b>(y, x); SolidBrush sb = new SolidBrush(Color.FromArgb(cx[2], cx[1], cx[0])); g.FillRectangle(sb, new Rectangle(x * PixelSize, y * PixelSize, PixelSize, PixelSize)); } } picResult.Image = bmp; 2.6 圆圈型像素放大算法

圆圈型像素放大算法是指将原图的每个像素放大为一个圆圈（派）显示。

Mat zmt = new Mat(src, new Rect(gx, gy, gw, gh)); Bitmap bmp = new Bitmap(picResult.Width, picResult.Height); Graphics g = Graphics.FromImage(bmp); g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; for (int y = 0; y < gh; y++) { for (int x = 0; x < gw; x++) { Vec3b cx = zmt.At<Vec3b>(y, x); SolidBrush sb = new SolidBrush(Color.FromArgb(cx[2], cx[1], cx[0])); g.FillEllipse(sb, new Rectangle(x * PixelSize, y * PixelSize, PixelSize, PixelSize)); } } picResult.Image = bmp; 2.7 鼠标事件与拾取框 private void PicSource_MouseMove(object? sender, MouseEventArgs? e) { if (picSource == null) { return; } if (picSource.Image == null) { return; } mouseAtX = e.X; mouseAtY = e.Y; abLocation.Text = mouseAtX + "," + mouseAtY + " " + (int)(mouseAtX / original_scale) + "," + (int)(mouseAtY / original_scale); int gw = picResult.Width / PixelSize; int gh = picResult.Height / PixelSize; Bitmap bmp = new Bitmap(picSource.Width, picSource.Height); Graphics g = Graphics.FromImage(bmp); g.DrawImage( image: img, destRect: new Rectangle(0, 0, bmp.Width, bmp.Height), srcX: 0, srcY: 0, srcWidth: img.Width, srcHeight: img.Height, srcUnit: GraphicsUnit.Pixel); g.DrawRectangle(new Pen(Color.Yellow), mouseAtX - gw / 2, mouseAtY - gh / 2, gw, gh); picSource.Image = bmp; Zoom(); }

3 运行效果 3.1 一般的插值放大算法效果

3.2 块状大像素放大效果

3.3 圆圈像素放大效果

 

4 完整的源代码

无需做修改，界面设计，直接复制粘贴替换原来的 Form1.cs 即可。

using OpenCvSharp; #pragma warning disable CS8602 namespace Legal.Truffer.CVStar { public partial class Form1 : Form { string[] ImgExtentions = { "*.*|*.*", "JPEG|*.jpg;*.jpeg", "GIF|*.gif", "PNG|*.png", "TIF|*.tif;*.tiff", "BMP|*.bmp" }; private int original_width { get; set; } = 0; private int original_height { get; set; } = 0; private double original_scale { get; set; } = 0.0; private string sourceImage { get; set; } = ""; private int PixelSize { get; set; } = 15; private int mouseAtX { get; set; } = 0; private int mouseAtY { get; set; } = 0; Panel? panelTop { get; set; } = null; Panel? panelBotton { get; set; } = null; PictureBox? picSource { get; set; } = null; PictureBox? picResult { get; set; } = null; Button? btnLoad { get; set; } = null; RadioButton? rbSmooth { get; set; } = null; RadioButton? rbBlock { get; set; } = null; RadioButton? rbPie { get; set; } = null; Label? abLocation { get; set; } Image? img { get; set; } = null; Mat? src { get; set; } = null; public Form1() { InitializeComponent(); this.Text = "OPENCV C#编程入手教程 POWERED BY 深度混淆（CSDN.NET）"; this.StartPosition = FormStartPosition.CenterScreen; GUI(); this.Resize += FormResize; this.DoubleBuffered = true; } private void FormResize(object? sender, EventArgs? e) { if (this.Width < 200) { this.Width = 320; return; } if (this.Height < 200) { this.Height = 320; return; } mouseAtX = 0; mouseAtY = 0; GUI(); } private void GUI() { if (panelTop == null) panelTop = new Panel(); panelTop.Parent = this; panelTop.Top = 5; panelTop.Left = 5; panelTop.Height = 75; panelTop.Dock = DockStyle.Top; panelTop.BorderStyle = BorderStyle.FixedSingle; panelTop.BackColor = Color.FromArgb(220, 220, 255); if (panelBotton == null) panelBotton = new Panel(); panelBotton.Parent = this; panelBotton.Top = panelTop.Top + panelTop.Height + 1; panelBotton.Left = 0; panelBotton.Width = panelTop.Width; panelBotton.Height = this.Height - panelBotton.Top - 55; panelBotton.BorderStyle = BorderStyle.FixedSingle; if (picSource == null) picSource = new PictureBox(); picSource.Parent = panelBotton; picSource.Left = 5; picSource.Top = 5; picSource.Width = (panelBotton.Width - 10) / 2; picSource.Height = (panelBotton.Height - 10); picSource.BorderStyle = BorderStyle.FixedSingle; picSource.MouseMove += PicSource_MouseMove; picSource.DoubleClick += Load_Image; original_width = picSource.Width; original_height = picSource.Height; if (picResult == null) picResult = new PictureBox(); picResult.Parent = panelBotton; picResult.Left = picSource.Left + picSource.Width + 5; picResult.Top = picSource.Top; picResult.Width = picSource.Width - (picSource.Width % PixelSize); picResult.Height = picResult.Width; picResult.BorderStyle = BorderStyle.FixedSingle; if (btnLoad == null) btnLoad = new Button(); btnLoad.Parent = panelTop; btnLoad.Left = 5; btnLoad.Top = 5; btnLoad.Width = 90; btnLoad.Height = 38; btnLoad.Cursor = Cursors.Hand; btnLoad.Text = "Load"; btnLoad.BackColor = Color.FromArgb(255, 110, 0); btnLoad.Click += Load_Image; if (rbSmooth == null) rbSmooth = new RadioButton(); rbSmooth.Parent = panelTop; rbSmooth.Left = btnLoad.Left + btnLoad.Width + 5; rbSmooth.Top = btnLoad.Top + 5; rbSmooth.Text = "smooth"; rbSmooth.Cursor = Cursors.Hand; rbSmooth.Checked = true; if (rbBlock == null) rbBlock = new RadioButton(); rbBlock.Parent = panelTop; rbBlock.Left = rbSmooth.Left + rbSmooth.Width + 5; rbBlock.Top = btnLoad.Top + 5; rbBlock.Text = "block"; rbBlock.Cursor = Cursors.Hand; if (rbPie == null) rbPie = new RadioButton(); rbPie.Parent = panelTop; rbPie.Left = rbBlock.Left + rbBlock.Width + 5; rbPie.Top = btnLoad.Top + 5; rbPie.Text = "pie"; rbPie.Cursor = Cursors.Hand; if (abLocation == null) abLocation = new Label(); abLocation.Parent = panelTop; abLocation.Left = btnLoad.Left; abLocation.Top = btnLoad.Top + btnLoad.Height + 5; abLocation.Text = mouseAtX + "," + mouseAtY; PicAutosize(picSource); Zoom(); } private void Load_Image(object? sender, EventArgs? e) { OpenFileDialog openFileDialog = new OpenFileDialog(); openFileDialog.Filter = String.Join("|", ImgExtentions); if (openFileDialog.ShowDialog() == DialogResult.OK) { sourceImage = openFileDialog.FileName; img = Image.FromFile(sourceImage); picSource.Image = img; src = Cv2.ImRead(sourceImage); PicAutosize(picSource); Zoom(); } } private void PicAutosize(PictureBox pb) { if (pb == null) return; if (pb.Image == null) return; Image img = pb.Image; int w = original_width; int h = w * img.Height / img.Width; if (h > original_height) { h = original_height; w = h * img.Width / img.Height; } if (pb == picSource) { original_scale = (double)w / (double)src.Width; } pb.SizeMode = PictureBoxSizeMode.Zoom; pb.Width = w; pb.Height = h; pb.Image = img; pb.Refresh(); } private void Zoom() { if (picSource == null) return; if (picSource.Image == null) return; // ROI int gw = picResult.Width / PixelSize; int gh = picResult.Height / PixelSize; int gx = (int)(mouseAtX / original_scale) - gw / 2; if (gx < 0) gx = 0; int gy = (int)(mouseAtY / original_scale) - gh / 2; if (gy < 0) gy = 0; if (rbSmooth.Checked) { #if GRAPHICS_METHOD Bitmap bmp = new Bitmap(picResult.Width, picResult.Height); Graphics g = Graphics.FromImage(bmp); g.DrawImage( image: picSource.Image, destRect: new Rectangle(0, 0, bmp.Width, bmp.Height), srcX: gx, srcY: gy, srcWidth: gw, srcHeight: gh, srcUnit: GraphicsUnit.Pixel); picResult.Image = bmp; #else Mat zmt = new Mat(src, new Rect(gx, gy, gw, gh)); picResult.Image = CVUtility.Mat2Bitmap(zmt); PicAutosize(picResult); #endif } else if (rbBlock.Checked) { Mat zmt = new Mat(src, new Rect(gx, gy, gw, gh)); Bitmap bmp = new Bitmap(picResult.Width, picResult.Height); Graphics g = Graphics.FromImage(bmp); g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; for (int y = 0; y < gh; y++) { for (int x = 0; x < gw; x++) { Vec3b cx = zmt.At<Vec3b>(y, x); SolidBrush sb = new SolidBrush(Color.FromArgb(cx[2], cx[1], cx[0])); g.FillRectangle(sb, new Rectangle(x * PixelSize, y * PixelSize, PixelSize, PixelSize)); } } picResult.Image = bmp; } else if (rbPie.Checked) { Mat zmt = new Mat(src, new Rect(gx, gy, gw, gh)); Bitmap bmp = new Bitmap(picResult.Width, picResult.Height); Graphics g = Graphics.FromImage(bmp); g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; for (int y = 0; y < gh; y++) { for (int x = 0; x < gw; x++) { Vec3b cx = zmt.At<Vec3b>(y, x); SolidBrush sb = new SolidBrush(Color.FromArgb(cx[2], cx[1], cx[0])); g.FillEllipse(sb, new Rectangle(x * PixelSize, y * PixelSize, PixelSize, PixelSize)); } } picResult.Image = bmp; } } private void PicSource_MouseMove(object? sender, MouseEventArgs? e) { if (picSource == null) { return; } if (picSource.Image == null) { return; } mouseAtX = e.X; mouseAtY = e.Y; abLocation.Text = mouseAtX + "," + mouseAtY + " " + (int)(mouseAtX / original_scale) + "," + (int)(mouseAtY / original_scale); int gw = picResult.Width / PixelSize; int gh = picResult.Height / PixelSize; Bitmap bmp = new Bitmap(picSource.Width, picSource.Height); Graphics g = Graphics.FromImage(bmp); g.DrawImage( image: img, destRect: new Rectangle(0, 0, bmp.Width, bmp.Height), srcX: 0, srcY: 0, srcWidth: img.Width, srcHeight: img.Height, srcUnit: GraphicsUnit.Pixel); g.DrawRectangle(new Pen(Color.Yellow), mouseAtX - gw / 2, mouseAtY - gh / 2, gw, gh); picSource.Image = bmp; Zoom(); } } }