C#/ EmguCV – 将上传的HttpPostedFileBase转换为Emgu.CV.Mat

/// <param name="type">Mat element type

  /// <param name="channels">Number of channels

  /// <param name="data">
  /// Pointer to the user data. Matrix constructors that take data and step parameters do not  
  /// allocate matrix data. Instead,they just initialize the matrix header that points to the 
  /// specified data,which means that no data is copied. This operation is very efficient and 
  /// can be used to process external data using OpenCV functions. The external data is not 
  /// automatically deallocated,so you should take care of it.

  /// <param name="step">
  /// Number of bytes each matrix row occupies. 
  /// The value should include the padding bytes at the end of each row,if any.

> type的类型为CvEnum.DepthType,它是图像的深度,您可以传递CvEnum.DepthType.Cv32F,它代表32位深度图像,其他可能的值的形式为CvEnum.DepthType.Cv {x} {t },其中{x}是集{8,16,32,64}的任何值,{t}可以是Sfor Single或F for Float.
>频道,取决于图像的类型,但我认为你可以使用4来自ARGB.

对于其他2个参数,如果不需要优化部分,则可以使用Mat类的这个构造函数：

public Mat(int rows,int channels)

如果您真的想使用优化版本,那么(继续)：

> data,您可以传递Bitmap.GetHbitmap(),它将IntPtr返回给用户数据.
>一步,对于这个家伙,我会给你一个明智的猜测,如果每个像素你有4个通道,每个通道的范围从0到255(8位),8 * 4 = 32,所以对于每个单位的宽度你需要32位.假设这是正确的,每行有32 *宽度位,将其转换为字节((8 * 4)*宽度)/ 8 = 4 *宽度,这是通道数乘以图像宽度.

UPDATE

获取数据和步骤的其他方法是从BitmapData类,这样(摘自MSDN资源)：

Bitmap bmp = new Bitmap(Image.FromStream(httpPostedFileBase.InputStream,true,true));

// Lock the bitmap's bits.  
Rectangle rect = new Rectangle(0,bmp.Width,bmp.Height);

System.Drawing.Imaging.BitmapData bmpData =
    bmp.LockBits(rect,System.Drawing.Imaging.ImageLockMode.ReadWrite,bmp.PixelFormat);

// data = scan0 is a pointer to our memory block.
IntPtr data = bmpData.Scan0;

// step = stride = amount of bytes for a single line of the image
int step = bmpData.Stride;

// So you can try to get you Mat instance like this:
Mat mat = new Mat(bmp.Height,CvEnum.DepthType.Cv32F,4,data,step);

// Unlock the bits.
bmp.UnlockBits(bmpData);

没有测试过这个解决方案,但你可以尝试一下.
我的答案是基于Emgu代码here.,Bitmap IntPtr here以及post,这也帮助我进一步了解了这一点.

我已经看到了其他方法,除非你真的需要调用那个完整的构造函数,我会尝试这种方法,看起来更干净：

HttpPostedFileBase file //your file must be available is this context.

if (file.ContentLength > 0)
{
    string filename = Path.GetFileName(file.FileName);

    // your so wanted Mat!
    Mat img = imread(filename,CV_LOAD_IMAGE_COLOR);
}

注意

OpenCV documentation中有很棒的教程.只需看一下核心模块的可用教程.特别是这个one.