[小代码]转换彩色图为灰度图

public Bitmap toGrayscale(Bitmap bmpOriginal) {        final int height = bmpOriginal.getHeight();        final int width = bmpOriginal.getWidth();        final Bitmap bmpGrayscale = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);        final Canvas c = new Canvas(bmpGrayscale);        final Paint paint = new Paint();        final ColorMatrix cm = new ColorMatrix();        cm.setSaturation(0);        final ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);        paint.setColorFilter(f);        c.drawBitmap(bmpOriginal, 0, 0, paint);        return bmpGrayscale;    }