I figurated it out.
public static BufferedImage scaleImage(BufferedImage image, double factorW, double factorH)
{
BufferedImage scaled = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_ARGB);
AffineTransformOp op = new AffineTransformOp(
AffineTransform.getScaleInstance(factorW, factorH), null);
image = op.filter(image, null);
scaled.getGraphics().drawImage(image, 0, 0, image.getWidth(), image.getHeight(), null);
return scaled;
}