Place an image on an image

Question

I want to place an image on a captured video frame at the coordinates which I determined.

I asked that before and I have been told to use cvCopy and

Answer 1

void cvOverlayImage(IplImage* src, IplImage* overlay, CvPoint location, CvScalar S, CvScalar D)
{
 int x,y,i;

  for(x=0;x < overlay->width -10;x++)     
//replace '-10' by whatever x position you want your overlay image to begin. 
//say '-varX'
    {
        if(x+location.x>=src->width) continue;
        for(y=0;y < overlay->height -10;y++)  
//replace '-10' by whatever y position you want your overlay image to begin.
//say '-varY'
        {
            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(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);
        }
    }
}

To use it

cvOverlayImage(largerimage, overlayimage, cvPoint(10, 10), cvScalar(0.5,0.5,0.5,0.5), cvScalar(0.5,0.5,0.5,0.5)); 
//The cvPoint(10,10) can be the cvPoint(varX,varY) depending on how you write the function 
//and how you want to use it. 
//You cannot choose values less than 'varX' and 'varY' in this case
//else you would see a runtime error.