OpenCVSharp入门教程基础篇⑤——GaussianBlur高斯模糊算法

绝地灬酷狼 2023-01-23 14:52 49阅读 0赞

### 文章目录 ###

*  一、前文
 *  二、GaussianBlur高斯模糊算法流程
 *  三、界面布局
 *  四、功能实现
 *   *  4.1 打开图片
     *  4.2 GaussianBlur高斯模糊—源码
     *  4.3 GaussianBlur高斯模糊—参数讲解
 *  五、运行效果图

# 一、前文 #

> Gaussian Blur，高斯模糊  
> 减少图像噪声以及降低细节层次  
> 高斯平滑也用于计算机视觉算法中的预先处理阶段，以增强图像在不同比例大小下的图像效果（参见尺度空间表示以及尺度空间实现）。 从数学的角度来看，图像的高斯模糊过程就是图像与正态分布做卷积。由于正态分布又叫作高斯分布，所以这项技术就叫作高斯模糊。

# 二、GaussianBlur高斯模糊算法流程 #

![在这里插入图片描述][20210715194140666.png]

其中`r`是`模糊半径`，`σ`是正态分布的`标准偏差`。

在二维空间中，这个公式生成的曲面的等高线是从中心开始呈正态分布的同心圆。  
分布不为零的像素组成的卷积矩阵与原始图像做变换。每个像素的值都是周围相邻像素值的加权平均。  
原始像素的值有最大的高斯分布值，所以有最大的权重，相邻像素随着距离原始像素越来越远，其权重也越来越小。

# 三、界面布局 #

*  一个`Label`
 *  N个`Button`
 *  三个`Picture`  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70]

# 四、功能实现 #

## 4.1 打开图片 ##

private void openFileBtn_Click(object sender, EventArgs e)
     { 
         OpenFileDialog openfiledialog = new OpenFileDialog();
         openfiledialog.Filter = "PNG Files (*.png)|*.png|JPG Files (*.jpg)|*.jpg|GIF Files (*.gif)|*.gif";
         openfiledialog.RestoreDirectory = true;
         if (openfiledialog.ShowDialog() == DialogResult.OK)
         { 
             Console.WriteLine(openfiledialog.FileName);
             fileName = openfiledialog.FileName;
    
             //Mat src = new Mat("foo.png", LoadMode.Color);
             Mat src = new Mat(fileName);
             //Mat src = new Mat(fileName, ImreadModes.Color);
             var frameBitmap = BitmapConverter.ToBitmap(src);
    
             pictureBox1.Image?.Dispose();
             pictureBox1.Image = frameBitmap;
         }
     }

## 4.2 GaussianBlur高斯模糊—源码 ##

private void GaussianBlurBtn_Click(object sender, EventArgs e)
    { 
        mInput = new Mat(fileName);
        blur = new Mat(mInput.Rows, mInput.Cols, MatType.CV_8UC4);
    
        Size ksize = new OpenCvSharp.Size(5, 5);
        Point anchor = new Point(3, 3);
        BorderTypes borderType = BorderTypes.Constant;
    
        //Cv2.Blur(mInput, blur, ksize, anchor, borderType); //模糊
        Cv2.GaussianBlur(mInput, blur, ksize, 0);  //高斯模糊
    
        srcPictureBox.Image = BitmapConverter.ToBitmap(mInput);
        grayPictureBox.Image = BitmapConverter.ToBitmap(blur);
    }

## 4.3 GaussianBlur高斯模糊—参数讲解 ##

//
    // 摘要:
    // Blurs an image using a Gaussian filter.
    //
    // 参数:
    // src:
    // input image; the image can have any number of channels, which are processed independently,
    // but the depth should be CV_8U, CV_16U, CV_16S, CV_32F or CV_64F.
    //
    // dst:
    // output image of the same size and type as src.
    //
    // ksize:
    // Gaussian kernel size. ksize.width and ksize.height can differ but they both must
    // be positive and odd. Or, they can be zero’s and then they are computed from sigma*
    // .
    //
    // sigmaX:
    // Gaussian kernel standard deviation in X direction.
    //
    // sigmaY:
    // Gaussian kernel standard deviation in Y direction; if sigmaY is zero, it is set
    // to be equal to sigmaX, if both sigmas are zeros, they are computed from ksize.width
    // and ksize.height, respectively (see getGaussianKernel() for details); to fully
    // control the result regardless of possible future modifications of all this semantics,
    // it is recommended to specify all of ksize, sigmaX, and sigmaY.
    //
    // borderType:
    // pixel extrapolation method
    public static void GaussianBlur(InputArray src, OutputArray dst, Size ksize, double sigmaX, double sigmaY = 0, BorderTypes borderType = BorderTypes.Reflect101);

*  `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*

# 五、运行效果图 #

*  从左到右
 *  第一张是原图
 *  第二张是GaussianBlur高斯模糊结果图

`Size ksize = new OpenCvSharp.Size(3, 3);`  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 1]

`Size ksize = new OpenCvSharp.Size(5, 5);`  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 2]

`Size ksize = new OpenCvSharp.Size(15, 15);`  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 3]

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[20210715194140666.png]: /images/20221004/b815b5a56956495db57ed4d09ac679c9.png
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