import java.awt.geom.AffineTransform;

// uses bilinear interpolation
static BufferedImage scaleImage(BufferedImage before, double scale) {
  if (scale == 1) ret before;
  int w = before.getWidth();
  int h = before.getHeight();
  int neww = max(1, iround(w*scale)), newh = max(1, iround(h*scale));
  BufferedImage after = new BufferedImage(neww, newh, BufferedImage.TYPE_INT_ARGB);
  AffineTransform at = new AffineTransform();
  at.scale(scale, scale);
  AffineTransformOp scaleOp = 
     new AffineTransformOp(at, AffineTransformOp.TYPE_BILINEAR);
  ret scaleOp.filter(before, after);
}

static BufferedImage scaleImage(double scale, BufferedImage before) {
  ret scaleImage(before, scale);
}