Overlay an image in OpenCV using C++

OverlayImage.cpp

# OverlayImage function reproduced from: http://www.aishack.in/2010/07/transparent-image-overlays-in-opencv/

void OverlayImage(IplImage* src, IplImage* overlay, CvPoint location, CvScalar S, CvScalar D) {

    for(int x=0;xwidth;x++)
    {
        if(x+location.x >= src->width) continue;
        for(int y=0;yheight;y++)
        {
            if(y+location.y>=src->height) continue;

            CvScalar source = cvGet2D(src, y+location.y, x+location.x);
            CvScalar over = cvGet2D(overlay, y, x);
            CvScalar merged;
            for(int i=0;i<4;i++)
                merged.val[i] = (S.val[i]*source.val[i]+D.val[i]*over.val[i])
            cvSet2D(src, y+location.y, x+location.x, merged);
        }
    }
}