android怎样添加图片锐化功能,如何在android中锐化图像？

我想要锐化图像,我的代码如下：

public Bitmap RuiHuaBitmap(Bitmap bitmap) {

int width, height;

height = bitmap.getHeight();

width = bitmap.getWidth();

int red, green, blue;

int a1, a2, a3, a4, a5, a6, a7, a8, a9;

Bitmap bmpBlurred = Bitmap.createBitmap(width, height,bitmap.getConfig());

Canvas canvas = new Canvas(bmpBlurred);

canvas.drawBitmap(bitmap, 0, 0, null);

for (int i = 1; i < width - 1; i++) {

for (int j = 1; j < height - 1; j++) {

a1 = bitmap.getPixel(i - 1, j - 1);

a2 = bitmap.getPixel(i - 1, j);

a3 = bitmap.getPixel(i - 1, j + 1);

a4 = bitmap.getPixel(i, j - 1);

a5 = bitmap.getPixel(i, j);

a6 = bitmap.getPixel(i, j + 1);

a7 = bitmap.getPixel(i + 1, j - 1);

a8 = bitmap.getPixel(i + 1, j);

a9 = bitmap.getPixel(i + 1, j + 1);

red = (Color.red(a1) + Color.red(a2) + Color.red(a3) + Color.red(a4) + Color.red(a6) + Color.red(a7) + Color.red(a8) + Color.red(a9)) *(-1) + Color.red(a5)*9 ;

green = (Color.green(a1) + Color.green(a2) + Color.green(a3) + Color.green(a4) + Color.green(a6) + Color.green(a7) + Color.green(a8) + Color.green(a9)) *(-1) + Color.green(a5)*9 ;

blue = (Color.blue(a1) + Color.blue(a2) + Color.blue(a3) + Color.blue(a4) + Color.blue(a6) + Color.blue(a7) + Color.blue(a8) + Color.blue(a9)) *(-1) + Color.blue(a5)*9 ;

bmpBlurred.setPixel(i, j, Color.rgb(red, green, blue));

}

}

return bmpBlurred;

}

但我无法达到理想的效果.有人可以提供更多线索,或者告诉我代码中的错误是什么？

谢谢.