C++端opencv代码：

#define DLL_API __declspec(dllexport)

extern "C" 

{

DLL_API int opencvtest(unsigned char* src, int w, int h, int channel);

}

int DLL_API opencvtest(unsigned char* src, int w, int h, int channel)

{

int format;

switch (channel)

{

case 1:

format = CV_8UC1;

break;

case 2:

format = CV_8UC2;

break;

case 3:

format = CV_8UC3;

break;

default:

format = CV_8UC4;

break;

}

//int lineByte = (w + 3) / 4 * 4;

Mat img(h, w, format, src);

int thickness = -1;

int lineType = 8;

//画一个圆

circle(img,

Point(200,200),

w / 16,

Scalar(0, 0, 255),

thickness,

lineType);

//img.data = src;

namedWindow("test1", CV_WINDOW_FREERATIO);

resizeWindow("test1", 800, 600);

imshow("test1", img);

return 1;

}

C#端代码：

[DllImport("testDll.dll", EntryPoint = "opencvtest", SetLastError = true, CharSet = CharSet.Ansi)]

extern static int opencvtest(byte[] src, int w, int h, int channel);

Bitmap bmp = new Bitmap("1.bmp");      

pictureBox1.Image = bmp;

int stride;

byte[] source = GetBGRValues(bmp, out stride);

int channel = Image.GetPixelFormatSize(bmp.PixelFormat) / 8;

opencvtest(source, bmp.Width, bmp.Height, channel);//opencv对内存操作，画了一个圈

pictureBox2.Image = getBitmapByBytes(source, bmp.Width, bmp.Height, stride, bmp.PixelFormat);//从byte[]数组中获取到的图像已经有画圈了，证明传输通信成功

/// <summary>

/// 生成灰度图的调色板

/// </summary>

/// <returns></returns>

public static ColorPalette getGrayPalette()

{

    // 下面的代码是为了修改生成位图的索引表，从伪彩修改为灰度 

    ColorPalette tempPalette;

    using (Bitmap tempBmp = new Bitmap(1, 1, System.Drawing.Imaging.PixelFormat.Format8bppIndexed))

    {

tempPalette = tempBmp.Palette;

    }

    for (int i = 0; i < 256; i++)

    {

tempPalette.Entries[i] = System.Drawing.Color.FromArgb(i, i, i);

    }

    return tempPalette;

}

/// <summary>

/// 从图像Byte数组获取Bitmap

/// </summary>

/// <param name="src"></param>

/// <param name="w"></param>

/// <param name="h"></param>

/// <param name="stride"></param>

/// <param name="format"></param>

/// <returns></returns>

public static Bitmap getBitmapByBytes(byte[] src, int w, int h, int stride, PixelFormat format)

{

    IntPtr ptr = getBytesPtr(src);

    int rowBytes = w * Image.GetPixelFormatSize(format) / 8;

    byte[] rgbValues = new byte[stride * h];

    for (var i = 0; i < h; i++)

    {

//int len = stride - (stride-rowBytes);

Marshal.Copy(ptr, rgbValues, i * stride, rowBytes);   //对齐

ptr += rowBytes; // next row

    }

    //Marshal.FreeHGlobal(ptr);

    ptr = getBytesPtr(rgbValues);

    Bitmap bitmap = new Bitmap(w, h, stride, format, ptr);

    if (format == PixelFormat.Format8bppIndexed)

    {

bitmap.Palette = getGrayPalette();   //如果是单通道灰度图，默认的bitmap调色板不对，需要手动设置

    }

    return bitmap;

}

/// <summary>

/// 获取bytes数组的头指针，非托管

/// </summary>

/// <param name="bytes"></param>

/// <returns></returns>

public static IntPtr getBytesPtr(byte[] bytes)

{

    GCHandle hObject = GCHandle.Alloc(bytes, GCHandleType.Pinned);

    return hObject.AddrOfPinnedObject();

}

/// <summary>

/// 获取bitmap的byte数据，并输出stride

/// </summary>

/// <param name="bmp"></param>

/// <param name="stride"></param>

/// <returns></returns>

public static byte[] GetBGRValues(Bitmap bmp, out int stride)

{

    var rect = new Rectangle(0, 0, bmp.Width, bmp.Height);

    var bmpData = bmp.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadOnly, bmp.PixelFormat);

    stride = bmpData.Stride;

    //int channel = bmpData.Stride / bmp.Width; 

    var rowBytes = bmpData.Width * Image.GetPixelFormatSize(bmp.PixelFormat) / 8;

    var imgBytes = bmp.Height * rowBytes;

    byte[] rgbValues = new byte[imgBytes];

    IntPtr ptr = bmpData.Scan0;

    for (var i = 0; i < bmp.Height; i++)

    {

Marshal.Copy(ptr, rgbValues, i * rowBytes, rowBytes);   //对齐

ptr += bmpData.Stride; // next row

    }

    bmp.UnlockBits(bmpData);

    return rgbValues;

}