表示灰度图像的int[][]，如何从有符号值转换为无符号值

public class GrayImageConverter {
    public static void main(String[] args) {
        int[][] grayImage = {{-128, -64, 0}, {-32, 64, 127}};

        // 将有符号值转换为无符号值
        for (int i = 0; i < grayImage.length; i++) {
            for (int j = 0; j < grayImage[i].length; j++) {
                grayImage[i][j] = grayImage[i][j] + 128;
            }
        }

        // 打印转换后的无符号值
        for (int i = 0; i < grayImage.length; i++) {
            for (int j = 0; j < grayImage[i].length; j++) {
                System.out.print(grayImage[i][j] + " ");
            }
            System.out.println();
        }
    }
}

0 64 128
96 192 255