struct IplImage
    {
        int Size;        /* sizeof(IplImage) */
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
        string ColorModel; /* ignored by OpenCV */
        IntPtr Roi;/* image ROI. if NULL, the whole image is selected */
        IntPtr MaskROI; /* must be NULL */
        IntPtr ImageId;    /* ditto */
        IntPtr TileInfo; /* ditto */
        string ImageData;  /* pointer to aligned image data */
        string ImageDataOrigin; /* pointer to very origin of image data 
                              (not necessarily aligned) - 
                              needed for correct deallocation */
    }