B-spline interpolation for image zooming opencv(c++)

See more:

C++

OpenCV

I have bicubic interpolation for image zooming but i want B-spline interpolation plz anyone help me.

code bicubic interpolation:

IplImage * bicubic(IplImage *img, int newWidth, int newHeight)
{
        int w= newWidth;
        int h = newHeight;
        IplImage * img2 =0;
        img2 = cvCreateImage(cvSize(w,h),IPL_DEPTH_8U,3);
        uchar * data =( uchar* ) img-imageData;
        uchar * Data =( uchar* ) img2-imageData;
       float tx,ty;

        tx = (float)img-width /newWidth ;
        ty =  (float)img-height / newHeight;

        float C[5] = { 0 };

for (unsigned i = 0; i<newHeight; ++i)
{
    for (unsigned j = 0; j<newWidth; ++j)
    {
        const int x = int(tx * j);
        const int y = int(ty * i);
        const float dx = tx * j - x, dx2 = dx * dx, dx3 = dx2 * dx;
        const float dy = ty * i - y, dy2 = dy * dy, dy3 = dy2 * dy;

        for (int k = 0; k<= 3; ++k)
        {
            for (int jj = 0; jj < 4; ++jj)
            {
                const int idx = y - 1 + jj;
                float a0 =data[(y-1+jj)*img-widthStep + (x)*img-nChannels +k];
                float d0 =data[(y-1+jj)*img-widthStep + (x-1)*img-nChannels +k] -          data[(y-1+jj)*img-gt;widthStep + (x)*img-nChannels +k];
                float d2 = data[(y-1+jj)*img-widthStep + (x+1)*img-nChannels +k] -         data[(y-1+jj)*img-widthStep + (x)*img-nChannels +k];
                float d3 = data[(y-1+jj)*img-widthStep + (x+2)*img-nChannels +k] - data[(y-1+jj)*img-widthStep + (x)*img-nChannels +k];
                float a1 = -(1.0f / 3.0f) * d0 + d2 - (1.0f / 6.0f) * d3;
                float a2 = 0.5f  * d0 +0.5f *  d2;
                float a3 = -(1.0f / 6.0f) * d0 - 0.5f * d2 + (1.0f / 6.0f) * d3;
                C[jj] = a0 + a1 * dx + a2 * dx2 + a3 * dx3;

                d0 = C[0] - C[1];
                d2 = C[2] - C[1];
                d3 = C[3] - C[1];
                a0 = C[1];
                a1 = -(1.0f / 3.0f) * d0 + d2 -(1.0f / 6.0f) * d3;
                a2 = 0.5f  * d0 +0.5f  * d2;
                a3 = -(1.0f / 6.0f) * d0 - 0.5f * d2 + (1.0f / 6.0f) * d3;
                Data[i*img2-widthStep +j*img2-nChannels +k ]=saturate( a0 + a1 * dy + a2 * dy2 + a3 * dy3 );
            }
        }<pre lang="c++">

}
}
return img2;
}