Use this method.
/**
* Rotates an image. Actually rotates a new copy of the image.
*
* @param img The image to be rotated
* @param angle The angle in degrees
* @return The rotated image
*/
public static Image rotate(Image img, double angle)
{
double sin = Math.abs(Math.sin(Math.toRadians(angle))),
cos = Math.abs(Math.cos(Math.toRadians(angle)));
int w = img.getWidth(null), h = img.getHeight(null);
int neww = (int) Math.floor(w*cos + h*sin),
newh = (int) Math.floor(h*cos + w*sin);
BufferedImage bimg = toBufferedImage(getEmptyImage(neww, newh));
Graphics2D g = bimg.createGraphics();
g.translate((neww-w)/2, (newh-h)/2);
g.rotate(Math.toRadians(angle), w/2, h/2);
g.drawRenderedImage(toBufferedImage(img), null);
g.dispose();
return toImage(bimg);
}
taken from my ImageTool class.
Hope it helps.