修改图像的pixelArray

Question

我有一种通过像素翻转图像的方法。但这样做会创造一个全新的形象。我怎么能修改现有图像？

private GImage flipHorizontal(GImage img) {

    int[][] array = img.getPixelArray();
    //width in pixels of each row of image
    int width = array[0].length;
    //loops through each row of the image
    for (int i = 0; i < array.length; i++) {
        //in each row flip each pixel horizontally
        for (int p1 = 0; p1 < width / 2; p1++) {
            int p2 = width - p1 - 1;
            int temp = array[i][p1];
            array[i][p1] = array[i][p2];
            array[i][p2] = temp;
        }
    }
    return ( new GImage(array));
}