ColorMatrix给图片去掉饱和度变灰

ImageView iv = new ImageView(this);
        Drawable drawable = getResources().getDrawable(R.drawable.icon);
        drawable.mutate();
        ColorMatrix cm = new ColorMatrix();
        cm.setSaturation(0);     
        ColorMatrixColorFilter cf = new ColorMatrixColorFilter(cm);     
        drawable.setColorFilter(cf);
        iv.setImageDrawable(drawable);
        setContentView(iv);