bitmap转emgucv image

在EmguCV中，可以使用`Bitmap`和`Image<Bgr, byte>`相互转换。下面是一个示例函数，将`Bitmap`转换为`Image<Bgr, byte>`：

public static Image<Bgr, byte> BitmapToImage(Bitmap bitmap)
{
    Image<Bgr, byte> image = new Image<Bgr, byte>(bitmap.Width, bitmap.Height);

    BitmapData bitmapData = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height),
                                            ImageLockMode.ReadOnly, bitmap.PixelFormat);

    int stride = bitmapData.Stride;
    int width = bitmap.Width;
    int height = bitmap.Height;

    unsafe
    {
        byte* sourcePtr = (byte*)bitmapData.Scan0.ToPointer();
        byte* destPtr = (byte*)image.DataPointer.ToPointer();

        for (int y = 0; y < height; y++)
        {
            for (int x = 0; x < width; x++)
            {
                byte b = sourcePtr[x * 3];
                byte g = sourcePtr[x * 3 + 1];
                byte r = sourcePtr[x * 3 + 2];

                destPtr[x * 3] = b;
                destPtr[x * 3 + 1] = g;
                destPtr[x * 3 + 2] = r;
            }

            sourcePtr += stride;
            destPtr += image.Stride;
        }
    }

    bitmap.UnlockBits(bitmapData);

    return image;
}

使用方式如下：

Bitmap bitmap = new Bitmap("test.bmp");
Image<Bgr, byte> image = BitmapToImage(bitmap);