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);