图像的裁剪，缩放

        //图像的裁剪，缩放
        CropImageFilter filter=new CropImageFilter(x,y,w,h);
        ReplicateScaleFilter filter=new ReplicateScaleFilter(w/2,h/2);
        AreaAveragingScaleFilter filter=new AreaAveragingScaleFilter(w/2,h/2);

        FilteredImageSource fis=new FilteredImageSource(im.getSource(),filter);
        im_des=createImage(fis);