unsigned width_max, height_max;
width_max = picture->width();
height_max = picture->height();
for (unsigned i=0 ; i<num_ ; i++)
{
  width_max = max(width_max, xPos[i]+stickers[i]->width());
  height_max = max(height_max, yPos[i]+stickers[i]->height());
}
Image output;
output.resize(width_max, height_max);
//copy the images
for (unsigned x = 0; x < picture->width(); x++)
for (unsigned y = 0; y < picture->height(); y++) {
  HSLAPixel & pixel = picture->getPixel(x, y);
  HSLAPixel & out = output.getPixel(x, y);
  out = pixel;
}
for (unsigned i=0; i<num_ ; i++)
{
  for (unsigned x = xPos[i]; x < xPos[i] + stickers[i]->width() ; x++)
  for (unsigned y = yPos[i]; y < yPos[i] + stickers[i]->height() ; y++) {
    HSLAPixel & pixel = stickers[i]->getPixel(x-xPos[i], y-yPos[i]);
    HSLAPixel & out = output.getPixel(x, y);
    if (pixel.a != 0)
    {
      out = pixel;
    }
  }
}
return output;
}